Bioplastics -a home inventors handbook

Bioplastics - A Home Inventors Handbook by Robert Murray-Smith Copyright 2013 Robert Murray-Smith

Smashwords Edition

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Contents Introduction Biopolymer materials Shaping of Molten Biopolymers Post-Formation Processing Articles Made From Biopolymers Biopolymer types Plasticisers Additives Recipes For Bioplastics Biopolymer Starch Composites Biopolymers from cereals Cellulose Based Bioplastics Sugar based Polymers Seaweed Based plastics

Chitin Protein Starch Composites Oat Based Plastics Where To Go From Here?

Introduction. Bioplastics is one of those areas that the home inventor has the advantage. The raw materials are cheap, readily available and easy to work with. There has been relatively little study done so far as the field is still quite new and there are a significant amount of discoveries to be made. What you have to realise here is that you are not attempting to synthesise polymers from monomers or synthesis new monomers. What you are trying to do is source and extract existing polymers from biological sources and turn those into useful products and usable plastics. The aim of this book is to give you a methodology for exploring bioplastics and creating your own. There are a LOT of recipes included. Mostly these are meant as a starting point and as a way of seeing the methodology in action. Biological polymers can be found in an enormous range of potential sources. Really the book is meant to encourage experimentation and all I really have to say is get out there and try. Sources of biological polymers would include fungi, molds, bacteria, seaweeds, plants, sugars, starches, crabs, lobsters, etc, etc - and these are only the ones being currently investigated. Though I mention in passing, so to speak, those polymers where the monomer is derived from biological sources, the main thrust of the book is in utilising those polymers that already exist. Bioplastics are commonly understood to be a form of plastics derived from renewable biomass sources, such as vegetable fats and oils, corn starch, pea starch or microbiota. Common plastics, such as fossil-fuel plastics, are derived from petroleum- these plastics rely more on scarce fossil fuels and produce more greenhouse gas. Some, but not all, bioplastics are designed to biodegrade. Being biodegradable is often seen as one of the hallmarks of a green plastic. Biodegradable bioplastics can break down in either anaerobic or aerobic environments, depending on how they are manufactured. There are a variety of materials bioplastics can be composed of, including: starches, cellulose, or other biopolymers. Preparing bioplastics on a small scale is not actually that difficult. On the whole the recipes are simple and the materials readily available and the possibilities endless. There are so many conceivable combinations no one can study them all - so you have as much chance as anybody else in coming up with a new bioplastic. In general they are prepared by the following equation biopolymer + plasticiser + other additives = bioplastic

Biopolymer Materials When we are thinking of biopolymer materials what we mean is materials that are generally capable of repeatedly softening when appropriately heated and hardening when subsequently cooled. Biopolymer materials are generally in a solid or form stable state below the melting point or softening range, while generally being in a plastic or flowable state above the melting point or softening range. The idea of solidity is that the material is sufficiently hardened, nonplastic or nonflowable such that it will substantially maintain its shape without external support. Of course, so called solid materials can have a degree of resilience, bendability or deformability and yet maintain their characteristic as being a “solid”. When something is thought of as plastic and flowable what we are thinking about are materials that can be moulded or otherwise shaped or deformed without causing significant damage to the structural matrix of the material upon resolidification. Thus, while a solid material can be bent or otherwise deformed, there is a point after which further movement or deformation could cause the structure to rupture, crack, or otherwise weaken irreversibly. Plastic or flowable materials, on the other hand, are characterized as being able to be shaped and deformed as desired while yielding a final solidified article having the same general strength properties upon solidification regardless of the degree of deformation while in a plastic state when normalized for variables such as thickness, size, shape, texture, molecular orientations, and so on. A biopolymer material is characterized in that it can be shaped into a desired article by first heating the material to a temperature above its melting point or softening range to form a flowable or plastic melt. The biopolymer melt can then be shaped into a desired article. Thereafter, or substantially at the same time of shaping, the shaped material is cooled sufficiently to cause it to harden or solidify and thereby form the desired article or intermediate material. The intermediate material can be further shaped or manipulated by reheating it to form a melt phase and then cooling to resolidify the shaped material. The degree of crystallinity can affect whether or not a biopolymer has at distinct or abrupt melting point. In general, the more crystalline a polymer is, the more distinct is its melting point. Conversely, more amorphous polymers tend to soften, melt and solidify over a range of temperatures. Thus, amorphous polymers do not have a distinct melting point but rather a softening or melting range. Because of this, more amorphous polymers have greater “melt stability”. That is, they can be melted and then shaped under conditions of high shear and pressure over a relatively broad range of temperatures without abruptly solidifying like more crystalline polymers. The softening or melting range generally becomes even broader as variability in the molecular weight of the individual polymer chains increases, which tends to further inhibit crystallization of the polymer molecules. The temperature at which a more amorphous polymer becomes soft enough to be shaped is generally significantly lower than the melting point of a more crystalline form of the same polymer. In other words, the softening or melting range of a more amorphous polymer can be substantially lower than the melting point of a more crystalline form of the same polymer. Thus, more amorphous polymers can often be

shaped at lower temperatures compared to similar polymers that are more crystalline. Conversely, more crystalline polymers can solidify more abruptly when cooled to below the melting point but will also exhibit greater dimensional stability when subsequently subjected to heat. More amorphous polymers tend to have greater flexibility and bending endurance while more crystalline polymers are more rigid and have a greater Young's modulus. Because more crystalline polymers have a more abrupt melting point above which the polymer is plastic and flowable and below which the polymer is a crystalline solid, further cooling of a crystalline polymer below its melting point will typically cause only minor incremental changes in its physical properties, if at all. On the other hand, more amorphous polymers, in addition to having a softening range, have what is known in the art as a “glass transition temperature” somewhere below the softening point or melt temperature at which they first become solid and dimensionally stable. Below the glass transition, temperature, amorphous polymers become considerably more rigid and brittle, while above this temperature they tend to be increasingly flexible and elastic. Thus, amorphous polymers exhibit greater dimensional stability and have increased modulus of elasticity below the glass, transition temperature. Conversely, they are more flexible, pliable and elastic above the glass transition temperature, although they can still have sufficient dimensional stability and resilience so as to be considered to be a “solid”. Although the glass transition temperature is often reported as a single value, it is known that the glass transition can actually occur over a temperature range and it is attributed a kinetic meaning. In some cases it can be possible to control the degree of crystallinity of a polymer by the manner in which a polymer melt is cooled. Cooling the polymer melt gradually as the temperature approaches the melting or softening point will increase the tendency of the polymer to become more crystalline. This is because slowly cooling the polymer allows the individual molecules to reorder themselves into more of a crystalline structure before the polymer actually becomes solid. Conversely, cooling a polymer melt more rapidly tends to maintain the polymer in a less crystalline and more amorphous state by quickly “freezing” (sometimes referred to as “quenching”) the individual molecules in a more random state before they have an opportunity to arrange themselves into a more crystalline structure. Biopolymers comprise a heterogeneous, though a preferably homogeneously mixed, mixture of at least two discrete phases, namely a biopolymer phase, a solid filler phase, and other optional phases. The biopolymer will typically comprise starch, a plasticiser, and optionally one or more other polymer materials or liquids that can be mixed or interspersed sufficiently with the starch so as to essentially constitute a single “biopolymer phase”. A biopolymer, whether a homogeneous material or a heterogeneous blend of hydrophobic and hydrophilic biopolymer phases, is characterized as generally being capable of forming a melt by heating to above a temperature, a temperature range, or a series of temperatures or temperature ranges and then resolidifying when cooled sufficiently. As such, the biopolymer is able to first become molten and then resolidified in order to bind the other components or phases together. The solid filler phase, on the other hand, should typically comprise individual particles or fibres dispersed throughout the biopolymer that themselves will not generally undergo a phase change to form a melt. Instead, the filler phase will remain

as a discrete discontinuous solid phase interspersed throughout and among the continuous biopolymer phase. Although it is possible for the filler to also interact with biopolymer, the filler will generally not assist in binding the components together. Other discrete phases can include a fibrous phase, comprising either organic or inorganic fibres, an organic filler phase comprising organic particles, and other organic or inorganic materials that can be in any state such as solid, gel, liquid, or gas and which for some reason do not become substantially commingled with the biopolymer so as to be considered part of that phase. Because each of the materials within any of the phases in the biopolymer can be selected to impart a unique property to the overall material, it is quite possible to microstructurally engineer a biopolymer best suited for a particular use based on given performance criteria of e.g., cost, strength, durability, degradability, esthetic appeal, density, flexibility, and so on. Really, it is a question of experimentation.

Shaping of Molten Biopolymers Once the biopolymerhave been processed into a molten state, they can be shaped into a huge variety of articles. Moreover, many shaping procedures used to form other materials such as ceramics can be modified and used to mold the biopolymers, particularly those that include a relatively high concentration of inorganic filler. In many cases it is desirable to first form the biopolymer into a granulate or bead by extruding the initially formed biopolymer through a die to form an extruded strand, which is thereafter cooled in a water bath, and then chopped into individual pieces. Such pieces can be stored, transferred and then used as desired in the manufacture of a wide variety of articles. Alternatively, the molten biopolymer can be immediately moulded into the desired final articles. Cooling an extruded strand with water prior to formation of a granulate will tend to cause a net absorption of water in the granulate. The absorption of water begins at the moment the extrudate is cooled or quenched in water, and continues so long as the strand or granulates are moist and/or exposed to relatively humid ambient conditions. Of course, water that is reabsorbed should be understood to be “loosely bound” in the sense that once the biopolymer starch phase has solidified, the absorbed water is only absorbed superficially and is not believed to become incorporated substantially within and between the biopolymer in the same manner as the water and/or plasticiser that is mixed with the starch while in a melted state. In general, biopolymers that are cooled with water will absorb from about 1% to about 6% by weight of loosely bound water. In most cases, the shaping process also includes cooling the shaped biopolymer to below its melting point or softening range in order to yield a solidified article. Depending on the type of article being manufactured, as well as the intended use of the article, it can be preferable to control the degree of crystallinity of the solidified biopolymer phase. In most cases, the type and quantity of plasticiser and other polymers blended with the starch component will have the greatest effect on the crystallinity of biopolymer, as discussed more fully above. Nevertheless, it can also be possible to affect the degree or percentage of crystallinity by controlling the rate at which the shaped biopolymerare cooled.

As with other polymers, the degree of crystallinity of the biopolymer and other polymers within the biopolymer can be increased if the molten biopolymer is cooled more slowly. For example, if a starch melt is cooled slowly so that its temperature is maintained within the softening range for a relatively long time, the molecules can be allowed to rearrange themselves into a lower energy crystalline state. On the other hand, cooling a starch melt more quickly will tend to maintain the solidified product in a more amorphous, and less crystalline state. Controlling the degree of crystallinity by means of controlling compositional as well as processing variables, can be helpful in engineering a final product having desired properties. On the one hand, solidified biopolymers that have lower crystallinity and which are more amorphous will generally have greater tensile strength, flexibility, bending endurance, and will behave like a wide variety of conventional biopolymer polymers. On the other hand, such compositions will generally be more sensitive to heat over a wider range of temperatures. Thus, more highly crystalline biopolymer compositions can be more suited for the manufacture of articles that need to be more heat-resistant, such as microwavable containers. Because more amorphous compositions tend to soften at lower temperatures due to such polymers having a wider softening range compared to crystalline polymers which have a more distinct melting point, they can have the tendency to soften when heated in a microwave oven. In contrast, compositions having a greater degree of crystallinity will tend to remain more rigid until heated to even higher temperatures and for longer periods of time compared to more amorphous polymers. The same is true for more amorphous polymers that are cooled to or below their glass transition temperature.

Post-Formation Processing Once an appropriate article has been formed from a biopolymer, it can be further processed in order to obtain the desired mechanical or physical properties. Postformation processes include conversion of one article into another, such as the formation of containers or other articles from sheets, remelting, coating, monoaxial and biaxial stretching of sheets, lamination with one or more other sheets or films, corrugation, creping, parchmenting, scoring and perforation of sheets, printing and expansion. Coatings can be used with the biopolymer to improve some qualities for example: paraffin (synthetic wax); shellac; xylene-formaldehyde resins condensed with 4,4′isopropylidenediphenolepichlorohydrin epoxy resins; polyurethanes; drying oils; reconstituted oils from triglycerides or fatty acids from the drying oils to form esters with various glycols (butylene glycol, ethylene glycol), sorbitol, and trimethylol ethane or propane; synthetic drying oils including polybutadiene resin; natural fossil resins including copal (tropical tree resins, fossil and modern), damar, elemi, gilsonite (a black, shiny asphaltite, soluble in turpentine), glycol ester of damar, copal, elemi, and sandarac (a brittle, faintly aromatic translucent resin derived from the sandarac pine of Africa), shellac, Utah coal resin; rosins and rosin derivatives including rosin (gum rosin, tall oil rosin, and wood rosin), rosin esters formed by reaction with specific glycols or alcohols, rosin esters formed by reaction formaldehydes, and rosin salts (calcium resinate and zinc resinate); edible oils; phenolic resins formed by reaction of phenols with formaldehyde; polyester resins; epoxy resins, catalysts, and adjuncts; coumarone-indene resin; petroleum hydrocarbon resin (cyclopentadiene type); teipene resins; urea-formaldehyde resins and their curing catalyst; triazine-

formaldehyde resins and their curing catalyst; modifiers (for oils and alkyds, including polyesters); vinyl resinous substances (polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol, etc.); cellulosic materials (carboxymethylcellulose, cellulose acetate, ethylhydroxyethylcellulose, etc.); styrene polymers; polyethylene and its copolymers; acrylics and their copolymers; methyl methacrylate; ethyl methacrylate; waxes (paraffin type I, paraffin type II, polyethylene, sperm oil, bees, and spermaceti); melamine; polyamides; polylactic acid, Biopol® (a polyhydroxybutyrate-hydroxyvalerate copolymer), polycaprolactone and other aliphatic polyesters; aliphatic-aromatic copolyesters; soybean protein; latexes; polyacrylates; other synthetic polymers including biodegradable polymers; and elastomers and mixtures thereof. Appropriate inorganic coatings include sodium silicate, calcium carbonate, aluminum oxide, silicon oxide, kaolin, clay and ceramics. Again this is an area limited only by your imagination Of course, it should be understood that the biopolymerof the present invention can themselves be used as coating materials in order to form a synergistic composite with, or otherwise improve the properties of, any number of other materials. Such disparate materials such as paper, paperboard, molded starch-bound articles such as starchbased foams, metals, plastics, concrete, plaster, ceramics, and the like can be advantageously coated with a biopolymer.

Articles Made From Biopolymers Due to the wide variety of properties that can be microstructurally engineered into a biopolymer, it is possible to manufacture a wide variety of finished articles that can presently be made plastics, paper, paperboard, polystyrene, metals, ceramics, and other materials. Merely by way of example, it is possible to manufacture the following exemplary articles: films, bags, containers, including disposable and nondisposable food or beverage containers, cereal boxes, sandwich containers, “clam shell” containers (including hinged containers used with fast-food sandwiches such as hamburgers), drinking straws, plastic baggies, golf tees, buttons, pens, pencils, rulers, cassette tape boxes, CD containers, cassette tapes, business cards, toys, tools, Halloween masks, building products, frozen food boxes, milk cartons, fruit juice containers, yoghurt containers, beverage carriers (wraparound basket-style carriers, and “six pack” ring-style carriers), ice cream cartons, cups, french fly containers, fast food carryout boxes, packaging materials such as wrapping paper, spacing material, flexible packaging such as bags for snack foods, bags with an open end such as grocery bags, bags within cartons such as a dry cereal box, multiwall bags, sacks, wraparound casing, support cards for products which are displayed with a cover (particularly plastic covers disposed over food products such as lunch meats, office products, cosmetics, hardware items, and toys), computer chip boards, support trays for supporting products (such as cookies and candy bars), cans, tape, and wraps (including, but not limited to, freezer wraps, tire wraps, butcher wraps, meat wraps, and sausage wraps); a variety of cartons and boxes such as corrugated boxes, cigar boxes, confectionery boxes, and boxes for cosmetics; convoluted or spiral wound containers for various products (such as frozen juice concentrate, oatmeal, potato chips, ice cream, salt, detergent, and motor oil), mailing tubes, sheet tubes for rolling materials (such as wrapping paper, cloth materials, paper towels and toilet paper), and sleeves; printed materials and office supplies such as books, magazines, brochures, envelopes, gummed tape, postcards, three-ring binders, book covers, folders, and pencils; various eating utensils and storage containers such as dishes, lids, straws,

cutlery, knives, forks, spoons, bottles, jars, cases, crates, trays, baking trays, bowls, microwaveable dinner trays, “TV” dinner trays, egg cartons, meat packaging platters, disposable plates, vending plates, pie plates, and breakfast plates, emergency emesis receptacles (i.e., “barf bags”), substantially spherical objects, toys, medicine vials, ampules, animal cages, firework shells, model rocket engine shells, model rockets, coatings, laminates, and an endless variety of other objects.

Biopolymer types Starch-based plastics Constituting about 50 percent of the bioplastics market, biopolymer starch, currently represents the most widely used bioplastic. Flexibiliser and plasticiser such as sorbitol and glycerine are added so the starch can also be processed thermo-plastically. By varying the amounts of these additives, the characteristic of the material can be tailored to specific needs. The simpler forms of starch plastics are what most people make at home. Cellulose-based plastics What is often forgotten is that cellulose based plastics are amongst the earliest form of bioplastic. They are composed mostly of cellulose esters, (including cellulose acetate and nitrocellulose) and their derivatives, including celluloid, viscose and cellophane. Sugar based plastics Agar is a gelatinous substance derived by boiling a polysaccharide in red algae, where it accumulates in the cell walls of agarophyte and serves as the primary structural support for the algae's cell walls. Agar is a mixture of two components: the linear polysaccharide agarose, and a heterogeneous mixture of smaller molecules called agaropectin. Throughout history into modern times, agar has been chiefly used as an ingredient in desserts throughout Asia and also as a solid substrate to contain culture medium for microbiological work. Agar (agar-agar) can be used as a laxative, an appetite suppressant, vegetarian gelatin substitute, a thickener for soups, in fruit preserves, ice cream, and other desserts, as a clarifying agent in brewing, and for sizing paper and fabrics. The gelling agent is an unbranched polysaccharide obtained from the cell walls of some species of red algae or seaweed. In chemical terms, agar is a polymer made up of subunits of the sugar galactose. Polylactic acid (PLA) is a transparent plastic produced from cane sugar or glucose. It not only resembles conventional petrochemical mass plastics (like Polyethylene or Polypropylene) in its characteristics, but it can also be processed on standard equipment that already exists for the production of conventional plastics. Polyglycolic acid (PGA) is a biodegradable, biopolymer and the simplest linear, aliphatic polyester. It can be prepared starting from glycolic acid by means of polycondensation or ring-opening polymerization. PGA has been known since 1954 as a tough fibre-forming polymer and is sugar based.

Polyamides A polyamide is a polymer containing monomers of amides joined by peptide bonds. They can occur both naturally and artificially, examples being proteins, such as wool and silk, and can be made artificially through step-growth polymerization or solidphase synthesis, examples being nylons, aramids, and sodium poly(aspartate). Polyamides are commonly used in textiles, automotives, carpet and sportswear due to their extreme durability and strength. The first polyamide was Parkesine, the first human-made polymer. It wascreated by inventor Alexander Parkes in 1856 out of chloroform and castor oil. Nylon is perhaps the most famous polyamide (though not a bioplastic and not biodegradable) Bio-derived polyethylene The basic building block of polyethylene is ethylene. This is just one small chemical step from ethanol, which can be produced by fermentation of agricultural feedstocks such as sugar cane or corn. Bio-derived polyethylene is chemically and physically identical to traditional polyethylene – it does not biodegrade but can be recycled. Genetically modified bioplastics Genetic modification (GM) is also a challenge for the bioplastics industry. None of the currently available bioplastics – which can be considered first generation products – require the use of GM crops, although GM corn is the standard feedstock.

Plasticisers Plasticisers for plastics are additives that increase the plasticity or fluidity of a material. Plasticisers work by embedding themselves between the chains of polymers, spacing them apart (increasing the "free volume"), and thus significantly lowering the glass transition temperature for the plastic and making it softer. For plastics such as PVC, the more Plasticisers added, the lower its cold flex temperature will be. This means that it is more flexible and its durability will increase as a result of it. Plasticisers evaporate and tend to concentrate in an enclosed space; the "new car smell" is caused mostly by plasticisers evaporating from the car interior. Plasticisers make it possible to achieve improved compound processing characteristics, while also providing flexibility in the end-use product. Two of the most common and easily available Plasticisers are glycerol (glyverine) and sorbitol. Although not an exhaustive list, examples of preferred plasticisers that can be used alone or together in various mixtures include ethylene glycol, propylene glycol, glycerin, 1,3-propanediol, 1,2-butandiol, 1,3-butandiol, 1,4-butanediol, 1,5pentandiol, 1,5-hexandiol, 1,6-hexandiol, 1,2,6-hexantriol, 1,3,5-hexantriol, neopentylglycol, sorbitol acetate, sorbitol diacetate, sorbitol monoethoxylate, sorbitol diethoxylate, sorbitol hexaethoxylate, sorbitol dipropoxylate, aminosorbitol, trihydroxymethylaminomethane, glucose/PEG, the reaction product of ethylene oxide with glucose, trimethylolpropane monoethoxylate, mannitol monoacetate, mannitol monoethoxylate, butyl glucoside, glucose monoethoxylate, α-methyl glucoside, the sodium salt of carboxymethylsorbitol, polyglycerol monoethoxylate, erythritol,

pentaerythritol, arabitol, adonitol, xylitol, mannitol, iditol, galactitol, allitol, sorbitol, polyhydric alcohols generally, esters of glycerin, formamide, N-methylformamide, DMSO, mono- and diglycerides, alkylamides, polyols, trimethylolpropane, polyvinylalcohol with from 3 to 20 repeating units, polyglycerols with from 2 to 10 repeating units, and derivatives of them. Examples of derivatives include ethers, thiethers, inorganic and organic esters, acetals, oxidation products, amides and amines. In general, more preferred plasticisers have a solubility parameter of at least about 15 kg½cm−{fraction (3/2)} within a temperature range of about 150-300° C., and most preferably in a range from about 15 kg½cm−{fraction (3/2)} to about 25 kg½cm− {fraction (3/2)}. Such plasticisers can be blended with a wide variety of other cosolvents or plasticisers both within and without the solubility parameter ranges. The concentration of plasticiser that can be used can vary greatly depending on the type of biopolymer and plasticiser being used, as well as on the identity and concentration of other possible components within biopolymer. In some cases it can be desirable to use a mixture of different plasticisers in order to impart specific properties. In general, the plasticiser can have a concentration in range from about 1% to about 70% by weight of the plastic. Plasticisers yield plastic compositions that tend to remain more stable, more flexible, less crystalline, and less brittle over time. They do this by keeping the plastic more amorphous over time. By remaining interposed between the various polymer chains within a composition, the plasticiser can better inhibit recrystalization and retrogradation of the starch chains compared to water or other more volatile plasticisers. Nevertheless, some plasticisers have a vapor pressure that allows for significant, albeit slow, evaporation. Such evaporation can be more pronounced when an article made from a biopolymer composition is exposed to heat. An example of a plasticiser that has a significant vapor pressure is glycerin. Where a plasticiser can tend to evaporate or otherwise migrate out of a plastic over time, it can be preferable in some cases to also include a higher molecular weight plasticiser that has a much lower vapor pressure in order to inhibit migration and loss of the higher vapor pressure, plasticiser from a solidified plastic. Moreover, because some higher molecular weight plasticisers are in a solid state at room temperature, they can remain more firmly embedded within biopolymerat room temperature compared to plasticisers that are liquid at room temperature. An example of a higher molecular weight plasticiser that has a much lower vapor pressure than glycerin and which is a solid at room temperature is sorbitol.

Additives In addition to the basic components of biopolymer, plasticiser and optional natural and synthetic polymers, other liquids, solids, or gases can be added to the plastic. It can also be possible to add a reactive agent that in addition to, or instead of, the additional biopolymer can improve the properties of the biopolymer. Such reactive agents can include cross-linking agents, used to cross link the biopolymer with either other biopolymer or the one or more additional polymers, reagents that add additional

functional groups to the polymer, reagents that can serve to block the hydroxyl functional groups on the starch polymers, and reagents that serve to form a phase mediator. Examples include monovalent, divalent, and polyvalent carboxylic acids, as well as their anhydrides, acid halides, and acid amides, epoxides, formaldehyde and/or urea and their derivatives, divinyl sulfones, isocyanates, oxo compounds such as acetone formaldehyde or polyvalent oxo compounds, cyanamide, dialdehydes, methylureas, and melamineformaldehyde resins. A good example is the addition of borax to PVA in the synthesis of silly putty and slime. Inorganic Fillers In many cases the inorganic fillers are substantially inert and unreactive and, as such, constitute a passive filler that does not contribute any additional binding or bonding activity. Filler particles that are capable of chemically bonding, interacting or otherwise associating with the biopolymer and other components in the are also used. Virtually any known filler, whether inert or reactive, can be incorporated into a bioplastic. In general, adding inorganic filler will tend to greatly reduce the cost. If a relatively small amount of inorganic filler is used, the effects on the strength of the final composition are minimized, while adding a relatively large amount of inorganic filler will tend to maximize those effects. In those cases where adding the inorganic filler will tend to detract from a critical physical parameter, such as tensile strength or flexibility, only so much of the filler should be added in order to reduce the cost of the resulting composition while retaining adequate mechanical properties required by the intended use. However, in those cases where adding the inorganic filler will improve one or more desired physical properties of a given application, such as stiffness and compressive strength, it can be desirable to maximize the quantity of added filler in order to provide this desired property while also proving greatly decreased cost. Because different types of inorganic fillers can impart different properties to the final plastic, two or more fillers can be used. You can select the types and amount of the various inorganic fillers that can be included within the plastic in order to engineer a final material. In general, in order to maximize the quantity of inorganic filler while mining the deleterious mechanical effects of adding the filler as much as possible, it will generally be preferable to select filler particles in a manner that decreases the specific surface area of the particles. The specific surface area is defined as the ratio of the total particle surface area versus the total particle volume. One way to decrease the specific surface area is to select particles that have a more uniform surface geometry. The more jagged and irregular the particle surface geometry, the greater is the ratio of surface area to volume of that particle - for example comparing sand to talcum powder. Another way to decrease the specific surface area is to increase the particle size. Particles that have decreased surface area generally require less of the biopolymer for lubrication in order to provide a desired rheology during mixing and moulding. Particles having decreased specific surface also require less plastic material for binding. Conversely, particles having increased surface area per unit volume of particles will generally require more of the biopolymer for lubrication during shaping and subsequent binding. Hence, all things being equal, decreasing the specific surface

area of the filler particles allows more of the filler to be used while maintaining desired mixture rheology. Similarly, decreasing the specific surface area of the filler particles allow more of the filler to be used while maintaining desired final strength properties. Related to decreased specific surface area in improving the rheology and final strength properties of the biopolymer is the concept of particle packing. Particle packing relates to the use of differently sized and graded filler particles that are selected in order for the particles to more completely fill the interstitial spaces between the particles. In general, the spaces between the particles is occupied by a corresponding quantity of the biopolymer. To be sure, a certain minimum amount of biopolymer material will always be required to adequately lubricate the particles during the shaping process and in order to subsequently bind the particles together. Nevertheless, poorly packed filler particles having excess interstitial space between them will require more of the biopolymer to occupy the interstitial space while not providing any additional lubricating and binding activity. Since both the actions of lubrication and the binding of particles are generally limited to regions immediately surrounding the particles, there is, for any given system of inorganic filler particles and biopolymer a “lubrication zone” and “binding zone”. Within the “lubrication zone”, the biopolymer is able to impart most if not all of its inherent lubrication activity. Thus, any biopolymer located outside this lubrication zone will constitute excess biopolymer so far as the operation of lubrication is concerned. Likewise, resolidified biopolymer located within the “binding zone” will impart most of its inherent binding activity, while polymer located outside the binding zone will constitute excess biopolymer so far as the binding function is concerned. Thus, it can be readily seen that biopolymer that is located outside of both the lubrication and binding zones can be considered to be excessive and wasteful in those cases where it is desired to maximize the inorganic filler content and thereby minimize the biopolymer content. In order to reduce the amount of biopolymer required to impart a given amount of lubrication and subsequent binding, it is advantageous to select particles that will pack together in a manner that reduces the interstitial space between the particles, particularly the “wasted” space that would otherwise be occupied by biopolymer. Particle packing techniques allow for a reduction in wasted interstitial space while maintaining adequate particle lubrication and, hence, mixture rheology, while also allowing for more efficient use of the biopolymer as a binder in the final hardened biopolymer. Simply stated, particle packing is the process of selecting two or more ranges of particle sizes in order that the spaces between a group of larger particles is substantially occupied by a selected group of smaller particles. In this manner, it is possible to select differently sized particles that maintain sufficient interstitial space to provide lubrication and binding zones, while reducing the volume of “wasted” space between the lubrication and binding zones that must otherwise be occupied by biopolymer. Eliminating the “wasted” space by filling these spaces with inorganic filler particles allows for the inclusion of more filler while maintaining the desired level of particle lubrication during shaping and particle binding upon solidification of a biopolymer. In order to optimize the packing density of the inorganic filler particles, differently sized particles having sizes ranging from as small as about 0.01 micron to as large as

about 2 mm can be used. Of course, the thickness and other physical parameters of the desired article to be manufactured from any given biopolymer can often dictate the upper particle size limit. In general, the particle packing is increased whenever any given set of particles is mixed with another set of particles having a particle size (i.e., width and/or length) that is at least about 2 times bigger or smaller than the first group of particles. The particle packing density for a two-particle system is maximized whenever the size ratio of a given set of particles is from about 3-10 times the size of another set of particles. Of course, three or more different sets of particles can be used to further increase the particle packing density. The degree of packing density that is “optimal” will depend on a number of factors including the types and concentrations of the various components within both biopolymer, the inorganic filler phase, and other optional phases, the shaping method that is employed, and the desired mechanical and other performance properties of the final articles to be manufactured from a given biopolymer. Examples of use full inorganic fillers that can be included within the biopolymer include such disparate materials as sand, gravel, crushed rock, bauxite, granite, limestone, sandstone, glass beads, aerogels, xerogels, mica, clay, synthetic clay, alumina, silica, fly ash, fumed silica, fused silica, tabular alumina, kaolin, microspheres, hollow glass spheres, porous ceramic spheres, gypsum dihydrate, insoluble salts, calcium carbonate, magnesium carbonate, calcium hydroxide, calcium aluminate, magnesium carbonate, titanium dioxide, talc, ceramic materials, pozzolanic materials, salts, zirconium compounds, xonotlite (a crystalline calcium silicate gel), lightweight expanded clays, perlite, vermiculite, hydrated or unhydrated hydraulic cement particles, pumice, zeolites, exfoliated rock, ores, minerals, and other geologic materials. Different inorganic fillers will impart their own unique surface characteristics to the composition and can be chosen accordingly. For example, kaolin gives a smoother, less porous finish, while plate-like materials such as mica and other clays yield a shiny surface. Typically, larger filler particles produce a matte surface, while smaller particles produce a glass-like surface. Substantially transparent fillers such as glass beads or spheres can be used to yield a substantially transparent or translucent biopolymer. Cement, gypsum and other similar materials are particularly useful filler materials because of their ready availability, extreme low cost, and because they can be used, if desired, to scavenge excess water that might be present within the biopolymer, thereby eliminating, or at least reducing, the deleterious effects of water. A wide variety of other inorganic fillers can be added to the biopolymer including materials such as metals and metal alloys (e.g., stainless steel, iron, and copper), balls or hollow spherical materials (such as glass, polymers, and metals), filings, pellets, flakes and powders (such as microsilica). Another class of inorganic fillers that can be added to the biopolymer includes inorganic gels and microgels such as silica gel, calcium silicate gel, aluminum silicate gel, and the like. These can be added in solid form or can be precipitated in situ. Since gels and microgels tend to absorb water, they can be added to reduce the negative effects of water within the biopolymer during processing, thereby increasing the

ability of starch to react with given reagents and biopolymer polymers. In addition, the highly hygroscopic nature of silica-based gels and microgels allows them to be used as moisture scavengers within the final hardened biopolymers. By preferentially absorbing moisture from the air, the gels and microgels can reduce moisture sensitivity of the biopolymers, particularly when exposed to high humidity, which can cause solidify plastics to soften. Controlling the moisture content of the biopolymer allows for more careful control of the elongation, toughness, modulus of elasticity, bendability, foldability, flexibility, and ductility of the finished article. Zeolites can also be added to preferentially absorb moisture in order to reduce the negative effects of moisture in biopolymers. The particle size or range of particle sizes of the inorganic fillers will depend on the wall thickness of the film, sheet, or other article that is to be manufactured from the biopolymer. In general, the larger the wall thickness, the larger is the acceptable particle size. In most cases, it is preferable to maximize the particle size within the acceptable range of particle sizes for a given application in order to reduce the cost and specific surface area of the inorganic filler. For films that are intended to have a substantial amount of flexibility, tensile strength and bending endurance (e.g., plastic bags) the particle size of the inorganic filler will preferably be less than about 10% of the wall thickness of the film. For example, for a blown film having a thickness of 40 microns, it is preferable for the inorganic filler particles to have a particle size of about 4 microns or less. On the other hand, thicker-walled articles, particularly those that are intended to be more rigid, can include inorganic fillers having a particle size up to about 50% of the wall thickness. Thus, for a rigid box having a wall thickness of 2 mm, the inorganic filler particles can have a particle size of up to about 1 mm. Due to the tremendous variety of articles and applications that are possible with a biopolymer preferred particle size can vary greatly. As the range of acceptable particle size increases, it can become more desirable to use particle packing techniques in order to incorporate more inorganic filler without comprising mechanical and strength performances. The amount of particulate filler added to the biopolymer will depend on a variety of factors, including the quantity and identities of the other added components, as well as the specific surface area and/or packing density of the filler particles themselves. Accordingly, the concentration of particulate filler within the biopolymer can be included in a broad range from as low as about 5% by volume to as high as about 90% by volume of the biopolymer. Because of the variations in density of the various inorganic fillers than can be used, it can be more correct in some instances to express the concentration of the inorganic filler in terms of weight percent rather than volume percent. In view of this, the inorganic filler components can be included within a broad range from as low as 5% by weight to as high as 95% by weight of the biopolymer. Fibres A wide range of fibres can optionally be used in order to improve the physical properties of a biopolymer. Like fillers, fibres will typically constitute a solid phase that is separate and distinct from the biopolymer. However, because of the shape of fibres, i.e., by having an aspect ratio greater than at least about 10:1, they can be added to improve the strength and toughness of the biopolymers. It should be

understood, however, that many applications, such as flexible, thin-walled blown bags, can not include any fibres. On the other hand, injection molded and foamed articles preferentially include fibres. Fibres can be added to the moldable mixture to increase the flexibility, ductility, bendability, cohesion, elongation ability, deflection ability, toughness, and fracture energy, as well as the flexural and tensile strengths of the resulting sheets and articles. Fibrous materials reduce the likelihood that the sheets, films or articles made from a biopolymer will shatter when cross-sectional forces are applied. Fibres that can be incorporated into the biopolymer include naturally occurring organic fibres, such as cellulosic fibres extracted from wood, plant leaves, and plant stems. Virtually any abundant fibre that can be harvested from natural sources will work. In addition, inorganic fibres made from glass, graphite, silica, ceramic, rock wool, or metal materials can also be used. Preferred fibres include cotton, wood fibres (both hardwood or softwood fibres, examples of which include southern hardwood and southern pine), flax, abaca, sisal, ramie, hemp, and bagasse because they readily decompose under normal conditions. However, other fibres such as glass fibres can be preferred depending on the intended use and performance criteria of the sheet or article. Even recycled paper fibres can be used in many cases and are extremely inexpensive and plentiful. The fibres used in making the sheets and other articles have a high length to width ratio (or “aspect ratio”) because longer, narrower fibres can impart more strength to the matrix without significantly adding bulk and mass. The amount of fibres added to a biopolymer will vary depending upon the desired properties of the final article, with tensile strength, toughness, flexibility, and cost being the principle criteria for determining the amount of fibre to be added in any mix design. Accordingly, the concentration of fibres within a biopolymer can be included in a broad range from 0% to about 90% by weight of the biopolymer. It is easy to appreciate that the strength and other mechanical properties of the fibre is a very important feature in determining the optimal amount of the fibre to be used. The greater the tensile strength of the fibre, the less fibre that will generally be required to impart a given tensile strength in the resulting product. While some fibres have a high tensile, tear, and burst strength, other types of fibres with a lower tensile strength can be more elastic and flexible. Including higher concentrations of fibres is particularly useful in these cases where relatively large quantities of inorganic filler have been added such that certain mechanical properties have been compromised. Including a substantial quantity of fibres, which are generally far less expensive than starch/polymer melts, can restore many of the properties that can be diminished as a result of including the inorganic filler component. In many cases it can be advantageous to include different types of fibres that impart differing properties to biopolymers. In this way the fibres can even impart synergistic properties to the biopolymer. For example, some fibres, such as southern pine and abaca, have high tear and burst strengths, while others, such as cotton, have lower strength but greater flexibility. In the case where both strength and flexibility are

desired, a combination of fibres having varying strength and other mechanical properties can be added to the mixture. Many fibres such as cellulosic fibres have an affinity for water. As such, they can act as a moisture reservoir to help regulate the moisture content of the biopolymer by absorbing or releasing moisture in response to fluctuations in the moisture content of the biopolymer. Nevertheless, if it is desirable to reduce the water affinity of the fibres, better water resistance can be obtained by treating the fibres with rosin and alum (Al2(SO4)3) or NaAl(SO4)2), which precipitates out the rosin onto the fibre surface, making the surface highly hydrophobic. The aluminum floc that is formed by the alum can create an anionic adsorption site on the fibre surface for a positively charged organic binder such as a cationic starch. Fibres can even be treated with lipids, fatty acids, and salts of fatty acids in order to make them less hydrophilic. Organic Fillers Biopolymer can also include a wide range of organic fillers. Depending on the melting point of the organic filler being added, the filler can remain as a discrete particle and constitute a solid phase separate from biopolymer, or it can partially or wholly melt and become partially or wholly associated with biopolymer. Whether it is desirable for the organic filler to be a filler or biopolymer material will depend on the particular application or use of the resulting biopolymer. Organic fillers can comprise a wide variety of natural occurring organic fillers such as, for example, seagel, cork, seeds, gelatins, wood flour, saw dust, milled polymeric materials, agar-based materials, and the like. Organic fillers can also include one or more synthetic polymers of which there is virtually endless variety. Because of the diverse nature of organic fillers, there will not generally be a preferred concentration range for the optional organic filler component. Void Phase A void phase, or voids, can be considered, in a sense as fillers consisting of a gaseous substance, in order to reduce the mass per unit volume (i.e. density) of the resulting biopolymer. Like the inorganic and organic fillers, voids occupy volume that would otherwise be occupied by the biopolymer and tend to therefore reduce the materials costs of the final biopolymer. Voids can also increase the insulating ability of articles manufactured from biopolymers. Like other fillers, the inclusion of void spaces can, in some cases, significantly decrease the strength of articles manufactured from the biopolymers. Thus, the amount of voids in relation to the other components should be controlled in order to yield materials having the requisite density and/or insulation properties while maintaining adequate strength for the intended use or application of the biopolymer. There are a variety of ways to introduce voids within the biopolymer, including mechanical and chemical means. For example, voids can be introduced into the biopolymer while in a molten state by means of high shear mixing. High shear auger extruders are one example of a high shear mixing apparatus that can be used to incorporate voids within the biopolymers as is an egg whisk! Because biopolymers are generally processed at elevated temperatures, the void volume will tend to increase as the materials are exposed to heat but will tend to decrease as the materials

are cooled. The relationship between expansion and contraction of the void spaces during processing can be considered when determining how much void space to be incorporated by mixing. Examples of gases that might be entrained within the biopolymer to form a void phase therein include air, CO2, nitrogen, noble gases, and the like. Alternatively, or in conjunction with mechanical incorporation of void spaces, you can use volatile solvents or other liquids that can vaporize and thereby yield void spaces as the biopolymers are heated and/or exposed to reduced pressure. Solvents and other liquids which can be considered to be “volatile” include any liquid or solvent that has a vapor pressure that is significantly greater than 1 bar at the melt temperature of the particular biopolymer in question. Examples include water, alcohols (such as methyl, ethyl, isopropyl and the like), ketones (such as acetone, methyl ethyl ketone and the like), aldehydes (such as formaldehyde, acetaldehyde and the like), carboxylic acids (such as formic, acetic acid and the like), acid anhydrides (such as acetic anhydride and the like), esters (such as ethyl acetate and the like), amines, and many other well-known solvents and liquids. Solid nucleating agents can be used in conjunction with volatile liquids to assist in forming discrete and wellformed voids. An example of solid nucleating agents are water-soaked fibres. Alternatively, or in conjunction with the foregoing void forming methods, it can be preferable in some cases to use chemically reactive foaming agents. An example of a chemically reactive foaming agent is a mixture of citric acid and bicarbonate, or bicarbonate that has been processed into small particles and coated with wax, starch, or water soluble coatings. Upon heating, the bicarbonate will decompose and yield carbon dioxide gas as a reaction product, which acts to expand the biopolymer. There are a wide variety of lightweight fillers that include significant quantities of void spaces. Thus, to the extent that a substantial fraction of the overall volume of a lightweight filler actually comprises voids, then the lightweight filler technically consists of both a solid phase as well as a void phase when viewed microscopically. Examples of lightweight filler that have substantial void space include hollow glass spheres, porous ceramic spheres, perlite, vermiculite, exfoliated geologic materials, and the like. Because such lightweight filler tend to be somewhat fragile, it is preferable to use low shear mixing when blending such fillers within a biopolymer. Another class of void forming agents include filler particles that are able to expand when heated. For example, an expandable particle can include a volatile liquid surrounded by a plastic or otherwise expandable shell. Upon heating, the volatile liquid undergoes a phase change from a liquid to a gas, which causes its volume to expand. This, in turn, causes the surrounding expandable shell to expand to thereby form a lightweight balloon or sphere. One such expandable particle, available from Akzo-Nobel located in Sweden, comprises an acrylonitrile shell surrounding a core of hexanes or heptanes which, upon heating, forms a lightweight balloon or sphere.

Effect of Components on a Biopolymer While in a Molten State In general, the viscosity and other properties of a biopolymer while in a molten state will directly relate to the type and amounts of the various components within the composition. Of course, while the biopolymer might be “molten” when viewed

macroscopically, the biopolymer will generally include both molten and solid components. Typically, the biopolymer while in a melted or molten state will include a liquid or plastic biopolymer in a melted or molten state that comprises a continuous phase or matrix and one or more generally solid disperse phases comprising inorganic filler particles and optionally fibres, organic fillers, and other solid components. The viscosity of the molten biopolymer itself is dependent on the viscosity of the biopolymer melt, optional biopolymer polymers, and other liquid components within the biopolymer while in a molten state. Although the viscosity of the biopolymer melt portion will depend to some degree on the type of plasticiser and polymer being used (e.g., the source of starch, such as potato or corn, or the degree to which is has been modified or denatured), the viscosity will especially depend on the amount of plasticiser that is added in relation to the polymer content. As more plasticiser is added, the viscosity of the melt will typically decrease at a given temperature. In general, adding liquids and additional biopolymer polymers having viscosities that are lower or greater than that of the melt will tend to lower or raise the viscosity of the molten biopolymer phase, respectively. In addition, any reactions between the polymer and other components might affect the viscosity of the biopolymer melt phase. As a general rule, but by no means the absolute rule in every case, reactions that result in polymer molecules having increased molecular weight will tend to increase the viscosity of the biopolymer melt phase. Thus, cross-linking reactions between the biopolymer themselves or between other components within the biopolymer will tend to increase the viscosity of the mixture. Similarly, reactions between the biopolymer and, for example, optional synthetic polymers, such as by addition, etherification, esterification, and the like will tend to increase mixture viscosity. On the other hand, hydrolysis or other cleaving reactions will tend to decrease mixture viscosity, all other things being equal. Because the inorganic filler and optional fibrous components will remain as discrete solids in most cases, and will not undergo a state change or become part of biopolymer, they will tend to increase mixture viscosity, particularly at higher concentrations. Thus, increasing the concentration of inorganic filler and optional fibrous components will tend to increase the viscosity of the biopolymers. Other factors that will affect mixture rheology include the morphology and specific surface area of the inorganic filler particles and optional fibres. In general, increasing the specific surface area and/or the irregularity of the filler particles and fibres will increase the viscosity since more of the biopolymer is required to coat and lubricate the inorganic filler particles and fibres. Conversely, decreasing the specific surface area and/or irregularity of the particle and fibre surfaces will decrease the viscosity, all other things being equal. In addition, increasing the particle packing density of an inorganic filler can greatly reduce the viscosity of molten biopolymers. By way of example, an inorganic filler particle system having a packing density of 0.65 will generally require about 35% by volume of the biopolymer to substantially fill the interstitial space between the particles. On the other hand, a filler particle system having a packing density of 0.95 will generally require only about 5% by volume of the biopolymer to substantially fill the voids. At the point where there is just enough of the biopolymer to fill the void spaces between the filler particles, even slight fluctuations in the concentration of the biopolymer can greatly affect the mixture rheology. A filler having a particle packing

density of 0.65 will require seven times the amount of biopolymer as a filler having a particle packing density of 0.95 to roughly achieve the same level of particle lubrication. This clearly shows the potentially substantial effects of particle packing density on mixture rheology. The inclusion of other admixtures such as dispersants, plasticisers and lubricants can greatly affect mixture rheology. Dispersants such as sulfonyl-based materials greatly decrease the viscosity and increase the workability of the mixture while keeping the amount of biopolymer constant. In addition, water scavengers such as zeolites and hydraulically reactive materials like cement can affect mixture rheology by eliminating water that might otherwise act to lubricate the biopolymer and/or that might inhibit condensation reactions between the starch and other polymers within a biopolymer. Organic fillers can affect mixture rheology in a variety of ways depending on the chemical makeup and physical properties of the organic filler being used. In the case where the organic fillers have a melting point above the softening point or range of the biopolymer such that they will remain essentially as solid particulate material, their effect on mixture rheology is similar to that of the inorganic filler particles. However, to the extent that the organic filler particles melt or at least soften due to increases in temperature, their viscosity-increasing effect is lessened. On the other hand, to the extent that the organic filler chemically reacts with the starch and/or other polymer component, the organic filler might tend to further increase the viscosity of the molten biopolymer. Of course, the biggest changes in mixture rheology will occur as a result of state changes of the biopolymer between solid and liquid states due to fluctuations in temperature, particularly in the region of the melting point or softening range of the biopolymer.

Additional Polymers In many cases it is desirable to include one or more additional polymers within a biopolymer in order to improve the properties of the resulting biopolymer. Both synthetic and natural polymers can be included within a biopolymer. Such polymers can improve the processability of the melts, although their major contribution will typically be to improve the mechanical and/or chemical properties of the final hardened biopolymer. For example, more hydrophobic polymers can be used to decrease the sensitivity of the final biopolymer to changes in ambient moisture and/or to make the material more water insoluble or impermeable. Depending on its chemical nature and, to some extent, the process and type of plasticiser being used, the additional biopolymer can or can not actually chemically interact with the biopolymer. Although virtually any biopolymer can be mixed with the biopolymer to some extent to form a blend intermixed biopolymer subphases, the biopolymer will exhibit more uniform mechanical properties where the biopolymer and additional polymer are more homogeneously intermixed. Of course, the additional polymer can be another biopolymer. It has been found that the most homogeneous blending occurs where at least a portion of the two polymers are chemically linked together, such as by a condensation reaction or some other chemical linking reaction. It would be ideal if substantially all of the biopolymer were to become chemically

linked with the other polymer(s). In many cases, however, only a portion is able to react with the other polymer(s). In such a case, it has been found that the portion of the biopolymer that reacts with the other polymer(s) will advantageously form a hybrid polymer that acts as a compatibilization subphase or phase mediator that yields a more homogeneously blended mixture of the unreacted phases of the biopolymer and other polymer(s). It should be understood, however, a wide variety of polymers that do not react can also be used. Examples of preferred biodegradable synthetic biopolymer polymers that can be blended with the biopolymer phase include: cellulose or cellulose derivatives such as cellulose acetate, cellulosic ethers, and carboxymethylcellulose; amylose, amylopectin, natural starch, or modified starches; polymers derived from reaction of diols (such as ethylene glycol, propylene glycol, butylene glycol, polyoxyethylene glycol, polyoxypropylene glycol, neopentyl glycol, 1,4-butandiol, cyclohexandiol, or dianhydrous sorbitol), polyester prepolymers, or polymers having diol terminal groups with: aromatic or aliphatic bifunctional isocyanates or epoxides, aliphatic bicarboxylic acids (such as malonic, succinic, maleic, fumaric, itaconic, glutaric, adipic, pimelic, suberic, azelaic, or sebacic acids), bicarboxylic cycloaliphatic acids (such as cyclohexane bicarboxylic acids or 2,2,2bicyclooctane bicarboxylic acid), or aromatic acids or anhydrides (such as phthalic acid); polyurethanes, polyamide-urethanes from diisocyanates and aminoalcohols, polyamides, polyester-amides from bicarboxylic acids and aminoalcohols, polyesterurea from aminoacids and diesters of glycols, polyhydroxylated polymers (such as polyvinylalcohol), ethylene-vinylalcohol copolymers, totally or partially hydrolyzed, and polysaccharides; polyvinylpyrrolidone, polyvinylpyrrolidonevinylacetate copolymers, polymethacrylates; As monomers of aliphatic hydroxyacids having from 2 to 24 carbon atoms, the following acids and corresponding lactides or lactones can be used: α-hydroxyacids such as lactic acids and the corresponding lactide, glycolic acid and the corresponding glycolide; β-hydroxyacids such as hydroxypropionic acid, hydroxypivalic and hydroxypelargonic acid and the corresponding lactone; γ-hydroxyacids such as hydroxybutyric and the corresponding lactone; δ-hydroxyacids such as hydroxyvaleric acid and the corresponding lactone;

ε-hydroxyacids; hydroxyacids having the hydroxy group placed beyond the 6-position such as 10hydroxydecanoic acid; products of natural origin such as sabinic acid (12hydroxydodecanoic) and juniperic acid (16-hydroxyhexadecanoic); unsaturated hydroxyacids such as ricinoleic acid; acids deriving from alphahydroxylation of fatty acids such as myristic, palmitic and stearic acids; acids deriving from hydroxylation of unsaturated fatty acids such as oleic, ricinoleic, linolenic and erucic acids; cycloaliphatic hydroxyacids such as the hydroxyacids of cyclohexane and of 2,2,2bicyclooctane. Homopolymers and copolymers of ε-hydroxyacids are preferred, particularly of 6hydroxycaproic acid, 6-hydroxyoctanoic, 3,7-dimethyl-6-hydroxyoctanoic acid and corresponding lactones, such as poly-ε-caprolactone. As copolymers of aliphatic hydroxyacids with isocyanates, copolymers of epsiloncaprolactone with 4,4′-diphenylmethane-diisocyanate (MDI), tolylenediisocyanate (TDI), isophoron diisocyanate or hexanmethylene diisocyanate are preferred. As the copolymers of aliphatic hydroxyacids and the corresponding lactones with aromatic hydroxyacids/copolymers of ε-caprolactone with β-phenyl lactic acid or mandelic acid are preferred. Another class of useful polyesters are the so-called “aliphatic-aromatic copolyesters” which have superior mechanical and physical properties by virtue of the aromatic portion, as well as good biodegradability as a result of the aliphatic portion. A presently useful aliphatic-aromatic copolyester is 1,4-butandioladipinic acid and teraphthalic acid with a chain extender comprising isocyanate. The foregoing polymers are preferred because they have been found to form good biopolymer blends of starch having good biodegradability and good mechanical and chemical properties. There is a huge variety of other polymers that can or can not react with the starch but that can be utilized with starch and other biopolymer precursors. These include polyolefines, alkylsiloxanes, polyesteramides, polyethers, polyethylene adipate (PEA), polytetramethylene adipate and the like aliphatic polyesters and their derivatives, cycloaliphatic polyesters and their derivatives, copolymers derived from a biopolymer synthetic resin and a biodecomposable aliphatic polyester, polyethylene, polypropylene, ethylene-vinylacetate copolymer and its saponified products, polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate, vinyl resins such as polyvinyl chloride, polyvinylidene acetate, polystyrene and styrene copolymers, polyamide resins, polycarbonate resins, cellulosic esters (e.g., cellulose formate, cellulose acetate, cellulose diacetate, cellulose propionate, cellulose butyrate, cellulose valerate, and mixtures of the foregoing), ethylene acrylate maleic acid and hydride terpolymer, polyacrylic acids, polycaprolactone/polyvinyl alcohol block copolymer, polysaccharides that have been chemically modified to contain added hydroxyalkyl groups, copolymers of vinyl pyrrolidone, polyalkyleneimine polymers and copolymers, styrene-sulfonic acid polymers, copolymers and salts thereof, and

virtually any polymer that can be biopolymerally processed at a temperature that would allow it to be blended with the biopolymer subphase. Examples of natural polymers or polymers derived from natural materials that can be blended into biopolymer plastics include a wide variety of cellulosic materials, proteins, and polysaccharide materials such as gums. Because cellulose is chemically similar to starch, cellulose based materials will have a greater affinity for starch compared to most other materials. One class of cellulose derived materials includes the cellulosic ethers, examples of which include ethylhydroxyethylcellulose, hydroxymethylethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxyethylpropylcellulose, and the like. Another class of cellulose derivatives are esters of cellulose, such as cellulose acetate, cellulose diacetate, cellulose formate, cellulose propionate, cellulose butyrate, mixed esters, and so on. Other polysaccharide-based polymers that can be incorporated into plastics include alginic acid, alginates, phycocolloids, agar, gum arabic, guar gum, acacia gum, carrageenan gum, furcellaran gum, ghatti gum, psyllium gum, quince gum, tamarind gum, locust bean gum, gum karaya, xanthan gum, and gum tragacanth. Suitable protein-based polymers include, for example, Zein (a prolamine derived from corn), collagen (extracted from animal connective tissue and bones) and derivatives thereof such as gelatin and glue, casein (the principle protein in cow milk), sunflower protein, egg protein, soybean protein, vegetable gelatins and gluten. Although it is preferable in many cases to reduce the water content of biopolymer, you can nevertheless use water as a significant portion of the plasticiser. In the case where it is not critical to reduce or eliminate water altogether, it can be advantageous to include one or more water-dispersible polymers. Examples of water-dispersible polymers that can be used in both the presence or absence of water include polyvinyl pyrrolidone, polyethylene glycol, polyvinyl alcohol, polyvinylmethyl ether, polyacrylic acids, polyacrylic acid salts, polyvinyl acrylic acids, polyvinyl acrylic acid salts, polyacrylimides, ethylene oxide polymers, polylactic acid, latex (which is a broad category that includes a variety of polymerizable substances formed in a water emulsion, an example of which is styrene-butadiene copolymer). As mentioned before, some polymers such as polyesters or other polycondensates can degrade or undergo chain shortening by hydrolysis if exposed to water at elevated temperature. Although replacing some or all of the water with a different plasticiser can reduce or prevent hydrolysis, some polymers such as polyesters can absorb significant amounts of moisture from the air. In such cases, it can be necessary to subject such polymers to a predrying step in order to prevent subsequent breakdown during thermal processing. Nevertheless, some degree of chain shortening can be desirable since it will increase the number of hydroxyl sites available for subsequent condensation with hydroxyl groups of the biopolymer subphase.

Effect of Components on Properties of Biopolymer When Solidified With regard to the final biopolymer, important mechanical, chemical, and other properties include tensile strength compressive strength, flexibility, modulus of

elasticity, ductility, fracture energy, the ability to elongate, deflect or bend, bending endurance, density, permeability to gases and liquids, resistance to water and other liquids, resistance to water vapour and other gases, thermal resistance, and specific heat are significantly affected by the composition of the components of the biopolymer. Different properties can be tailored to the particular performance criteria of the final article by altering the identity and relative concentration of the various components within a biopolymer. In some cases, higher tensile strength can be an important feature. In others, it can be less significant. Some articles should preferably be more flexible, while others should be more rigid. Some should be relatively dense, while others should be thicker, lighter, and more insulative. The important thing is to achieve a material which has properties appropriate for a particular use, while recognising the importance of cost and other practical manufacturing parameters. While having “too much” or “too little” of a particular property can be inconsequential from the standpoint of performance, from a cost standpoint it can be wasteful, inefficient or ineffectual to provide too much of a particular property, even if desired up to a certain point. Due to the tremendous variety of different biopolymer blends that can be made you will have an almost limitless supply of possible biopolymer phases and attendant properties from which to choose and experiment with. In general, increasing the concentration of polymers that have increasing tensile and other strength properties will increase the strength of the resulting biopolymer. The degree of water resistance of the biopolymer will, of course, greatly affect the water resistance of the overall composition. The elasticity and toughness of the biopolymer will have a significant effect on the final composition. Increasing the concentration of plasticiser will typically increase the flexibility and elasticity of biopolymer. Conversely, decreasing the amount of plasticiser will yield a stiffer, more brittle biopolymer phase. Thus, the identity and concentration of the plasticiser can greatly affect the final properties of the biopolymer. Low volatile plasticisers will tend to yield properties that remain substantially constant over time, while more volatile solvents such as water can evaporate away over time, yielding a biopolymer whose mechanical properties can change substantially over time. The degree of crystallinity of the biopolymer can greatly affect the mechanical properties of the biopolymer. In general, the more amorphous biopolymer, the greater is the tensile strength, flexibility, ductility, bending endurance, and other like properties of the composition. Conversely, the greater the crystallinity of biopolymer, the greater is the stiffness, Young's modulus, rigidity, and other like properties of the composition. In general, increasing the concentration of plasticiser will decrease the crystallinity of biopolymer, thereby making it more amorphous. In addition, the addition of dissimilar materials, such as additional polymers, blocking agents, and the like within the starch melt will tend to result in a solidified biopolymer that is more amorphous and less crystalline in nature. All things being equal, for a given biopolymer phase, increasing the concentration of the inorganic filler component will tend to decrease the tensile strength, reduce the flexibility, increase the stiffness, increase the compressive strength, decrease the ductility, and decrease the fracture energy of the resulting biopolymer. The effect of

the inorganic filler on the density will usually depend on the relationship between the density of the filler and biopolymer. Because most of the less expensive inorganic fillers have a density that is typically greater than most biopolymer phases, increasing the inorganic filler content will generally increase the density of the biopolymer. However, certain lightweight fillers can actually lower the density of the biopolymer. Lightweight fillers will also generally lower the thermal conductivity and specific heat of the biopolymer, while the effect of other inorganic fillers on such properties is variable. Because the general effect on desirable strength and other mechanical properties by adding inorganic filler can be negative, such negative effects can be offset by adding reinforcing fibres. Of course, fibres can also be added to impart these and other properties independent of an inorganic filler. In general, including more fibres will tend to increase the tensile strength, flexibility, compressive strength, tear and burst strength, ductility, fracture energy, and modulus of elasticity of the resulting biopolymer. In general, using longer, more flexible fibres will generally impart more flexibility to the biopolymer compared to shorter, stiffer fibres. In order to obtain the advantageous properties of different types of fibres, it can be preferable in some cases to combine two or more different kinds of fibres within the biopolymer. It should also be understood that shaping processes, such as extrusion and rolling will tend to orient the fibres in the direction of elongation of the biopolymer. This can be advantageous in order to maximize, for example, the tensile strength, flexibility, and bending endurance of the resulting article in a certain direction. Finally, other admixtures within the biopolymer such as cross-linking agents, lubricants, humectants, plasticisers, hydroxyl blocking groups, and the like can greatly affect the final properties, such as resistance to water or other liquids, impermeability to water vapour or other gases, ductility and strength.

Recipes For Bioplastics. Starch based bio plastics Starch is generally incapable of behaving as a biopolymer material by itself, or by itself in combination with a particulate filler. So, what is needed is to include some kind of melt-initiating agent that can cause the starch to behave in a biopolymer manner. The starch component of the biopolymer can be just about any known starch material, including one or more unmodified starches, modified starches, and starch derivatives. Nevertheless, preferred starches, both from the standpoint of cost and of processability, include most any unmodified starch that is initially in a native state as a granular solid and which will form a biopolymer melt by mixing and heating in the presence of an appropriate plasticiser. Starch is a natural carbohydrate chain comprising polymerized glucose molecules in an α-(1,4) linkage and is found in nature in the form of granules. Such granules are easily liberated from the plant materials by a whole variety of methods like chopping and washing. Starch granules include two different types of polymerized glucose chains: unbranched, singlechained amylose and branched multi-chained amylopectin.

In general, starch granules have a coating or outer membrane that encapsulates the more water soluble amylose and amylopectin chains within the interior of the granule. This outer shell makes unmodified native starch granules generally insoluble in water at room temperature. However, when heated in the presence of water or other polar solvent such as glycerin, the solvent is able to soften and penetrate the outer membrane and cause the inner starch chains to absorb water and swell. This swelling will, at some point, cause the outer shell to rupture and allow the irreversible gelatinization or destructurization of the starch granule. This process is irreversible because, once gelatinized or destructurized, starch can never revert to its native, cold water-resistant, granular state. The exact temperature at which starch will gelatinize in a given plasticizing solvent depends on the type of starch. In general, the higher the amylose content, the higher the gelatinization temperature in water due to the greater insolubility of amylose compared to amylopectin. In the presence of mixing, such as high shear mixing, the rate of melting or destructurization is greatly increased. Once gelatinized or destructurized, the various starch polymer chains comprising amylose and amylopectin polymers, which are initially compressed within the granules, will stretch out and form a generally disordered intermingling of polymer chains, particular while in a molten or gelatinized state. Upon resolidification, however, the chains can reorient themselves in a number of different ways in order to form crystalline or amorphous solids having varying strengths depending on the orientation of the starch polymer chains. Orienting, cross-linking, and reacting the polymer chains with other components can greatly affect the resulting physical and mechanical properties of the resolidified starch melt. Although starch is produced in many plants, an important source are seeds of cereal grains, such as corn, waxy corn, wheat, sorghum, rice, and waxy rice. Another important source includes tubers, such as potatoes, roots such as tapioca (i.e., cassava and manioc), sweet potato, and arrowroot, and the pith of the sago palm. In general, potato and waxy corn starches are generally higher in amylopectin, while corn and rice starches are generally higher in amylose. Depending on the desired properties of the final biopolymer, one can select the type of starch that will give the most desired benefits, both in terms of cost and final physical, mechanical and strength properties. The concentration of starch within the biopolymer can vary greatly depending on whether or not other constituents are added to the biopolymer. Because starch is not by itself a biopolymer material but must be admixed with one or more plasticisers, the concentration of biopolymer starch within the biopolymer is a mixture of starch and plasticiser. Thus, if the biopolymer were to contain 100% of a starch melt, the actual concentration of molecular starch would be less than 100%, with the balance comprising the plasticiser, as well as optional components, such as cross-linking agents, blocking groups, substitution groups, and the like. In some cases it can be particularly advantageous to use starch that has been predried to remove some or substantially all of the water that is naturally associated with native starches. Because this water can have a variety of possibly negative effects during the formation of starch melts, for example when it is desired to react the starch with another constituent by means of a condensation reaction, it can be advantageous to remove this water before mixing and heating the starch with the plasticiser to form a melt, or at least before reacting the starch melt with the other constituent.

Starch Plasticisers In making starch melts, there have been essentially two alternative approaches that utilize what can be considered to be two different plasticizing or melt initiating systems. For simplicity, these two alternative approaches can be referred to as “destructurized starch” and “biopolymer starch”. The term “destructurized starch” has typically been used when referring to processes for forming a starch melt in which the starch granules are made biopolymer by heating and mixing the starch in the presence of water. Because water is generally volatile at the temperatures necessary to form a starch melt, the destructurization process must generally take place within a closed vessel capable of preventing the escape of water by evaporation so as to maintain the desired concentration of water throughout the process. By maintaining a constant water concentration within the closed vessel, it is possible to form plastics in which the water acts as the primary or sole, plasticizing solvent. Upon cooling to below the melting or softening point or range, the destructurized starch melt resolidifies as a biopolymer material. Gelatinizing or destructurizing starch in any quantity of water will not always yield a starch material that will act as a biopolymer material, but only where sufficiently low water is used so that the resulting melting point or softening range is sufficiently higher than room temperature so as to reliably form a solidified product upon cooling. If too much water is used, the gelatinized starch can only be solidified by evaporating away a substantial portion of the water in order to either raise the melting point or softening range sufficiently or in order to dry it to the point of recrystalization so that it solidifies while being heated rather than after being cooled. In order for “destructurized starch” to behave as a biopolymer material that will solidify as a result of cooling sufficiently below its melting or softening point, it will generally be necessary for the water to be included in a range from about 5% to about 4% by weight of the starch (including the water naturally found in native starch). If more than about 40% is included, the melting point or range will usually be too low for the starch/water mixture to reliably solidify within a reasonable period of time when cooled. If the water is not maintained above about 5% throughout processing, and absent the inclusion of another plasticiser such as glycerin, the starch will usually not form or be maintained as a melt at a temperature sufficiently lower than the decomposition temperature of starch, which is about 230-250° C. One problem with using water as a melt initiation agent is that it can, in some cases, inhibit desired chemical reactions between the starch melt and other additives, unless removed by evaporation prior to the occurrence of such reactions. The reactive additive can be a nonpolymeric reagent, or it can comprise one or more biopolymer polymers that have reactive groups that can react with, e.g., the hydroxyl groups of the starch polymer. For example, it can be desirable to reduce the hydrophobicity of the starch polymer by reacting or otherwise blocking the hydroxyl groups such as by esterification, etherification, or other condensation reaction, or by substitution, elimination, or formation of acetal or ketal groups. Because water is a byproduct of condensation reactions, its presence within the starch melt can inhibit or even prevent such reactions. Water can also compete as a reactant with the starch in some cases. Certain polymers can also experience degradation or partial cleavage of the polymer chain when heated in the presence of water. For example, it is known that many

polyesters can experience chain degradation and reduction of molecular weight through hydrolysis reactions with water at elevated temperatures. Reducing the molecular weight of polymers tends to weaken films and other articles made therefrom. Although not known for sure, it can be possible for water to degrade or hydrolyze a significant proportion of the acetal linkages within biopolymer at elevated temperature, particularly under high shear conditions, which can reduce the molecular weight of the biopolymer to some extent. Thus, in order to prevent hydrolysis of polymer linkages within one or polymers within a biopolymer starch melt, it can be preferable to limit the length of time that certain polymers are exposed to substantial moisture at elevated temperatures. Destructurized starch can also tend to form retrograde starch over time as a result of moisture loss. Retrograde starch is much more brittle and less flexible compared to biopolymerhaving lower crystallinity. When destructurized plastics are initially formed, the water is able to interact with the hydroxyl groups of the biopolymer in order to interrupt the biopolymer and keep them from associating themselves into a more crystalline geometry. However, in normal ambient conditions the water within destructuized starch is free to migrate into and out of the destructurized starch over time, thus compromising the ability of the water to prevent crystallization and retrogradation of the destructurized starch. In view of the volatile nature of water and also the tendency of water to inhibit certain desired chemical reactions or hydrolyze certain polymers, another approach to making a starch melt is to substitute some or all of the water with less volatile plasticisers (e.g., glycerin) or even higher molecular weight plasticisers that are essentially nonvolatile. For simplicity, less volatile and nonvolatile plasticisers or solvents that have a vapor pressure of less than 1 bar at the melting temperature of the starch melt are collectively referred to as “low volatile” plasticisers. Conversely, melt initiators comprising volatile solvents (e.g., water, alcohols, amines, aldehydes, ketones, organic acids, esters, amides, imides, and the like) that have a vapor pressure of 1 bar or greater at the melting temperature of the starch melt are considered to be “volatile” melt initiators or solvents. In the past, some have referred to plastics that use low volatile plasticisers instead of water as “biopolymer starch”. On the other hand, starch that has been melted in the presence of water has been referred to as “destructurized starch”. A simple Starch Process A quick look on the Internet will reveal a whole host of recipes for plastics based on starch. Unfortunately most of them are limited to the boil in the pan type recipes consisting of little more than water, starch, glycerine and vinegar that yield pretty unsatisfactory results. A fairly typical recipe is: Ingredients Water Vinegar

Glycerine Starch The basic recipe Combine 7 parts water, 1 part vinegar, 1/2 part glycerine, 1 1/2 parts starch for the basic recipe. You heat this in a pan for several minutes and presto you have bioplastic. More glycerine makes for a harder plastic. More starch makes for a denser and less viscous plastic. Variant recipe An 8 parts water, 1 vinegar, 1 gycerine, 1.5 starch variant worked best for filling molds and was much easier to work with. A recipe with 4 tablespoons water, 1 starch and 1 teaspoon of both gylcerine and vinegar made for a bit tougher but also less uniform result. Combine the ingredients in the pan and stir until you get a smooth milk like consistency Put pan on medium heat and stir continually The mixture will 'turn' suddenly and become glue-like At this point stir and fold vigorously to keep residue from sticking to the pan The material will start to bubble, wait until you have large bubbles Cook for approximately 3 minutes in total until the material is nearly all see through. The above recipe does yield a result it far from explores the possibilities inherent in the basic material. Although the material made from previous example are not themselves an actual biopolymer, a biopolymer is formed from the following components (expressed in terms of parts by weight):

starch 100 parts glycerin 15 parts sorbitol 15 parts poly-ε-caprolactone (PCL) 130 parts calcium carbonate 260 parts as a side note Polycaprolactone (PCL) is a biodegradable polyester with a low melting point of around 60°C and a glass transition temperature of about −60 °C. The most common use of polycaprolactone is in the manufacture of speciality polyurethanes.

Polycaprolactones impart good water, oil, solvent and chlorine resistance to the polyurethane produced. This polymer is often used as an additive for resins to improve their processing characteristics and their end use properties (e.g., impact resistance). Being compatible with a range of other materials, PCL can be mixed with starch to lower its cost and increase biodegradability or it can be added as a polymeric plasticizer to PVC. Polycaprolactone is also used for splinting, modeling, and as a feedstock for prototyping systems such as a RepRap, where it is used for Fused Filament Fabrication. PCL also has many applications in the hobbyist market and is sold under various tradenames, such as "InstaMorph", "Friendly Plastic", "ShapeLock", "PolyMorph", "Plastimake", "Plaast" etc. All that aside let's call this material SPG1. The starch, which can be any kind of starch but a native potato starch having an initial moisture content of 17% by weight was used along with glycerin and sorbitol are blended for 1 minute at a temperature of 160-180° C. in order to form biopolymer starch melt. The starch melt is then blended with the poly-ε-caprolactone (PCL) for an additional minute and heated at a temperature of 170° C. in order to form a substantially homogeneous biopolymer comprising biopolymer starch and poly-ε-caprolactone. At least a portion of the biopolymer starch (TPS) and PCL undergo crossesterification to thereby form a TPS/PCL copolymer. The TPS/PCL copolymer results in a more homogeneous dispersion of the remaining TPS and PCL. The calcium carbonate is then added to the biopolymer melt and mixed for a minute or less in order to form a substantially homogeneously blended inorganically filled biopolymer. This composition can then be cooled and copped up into smaller pieces for remelting and shaping at a later date. The composition and process above can be repeated except that the amount of calcium carbonate added to the biopolymer is altered. As the concentration of calcium carbonate is decreased the resulting biopolymers have increased flexibility, tensile strength, toughness and fracture energy, but somewhat lower tensile strength. Conversely, as the concentration of calcium carbonate is increased the resulting biopolymer has increased stiffness, are more brittle, have somewhat increased compressive strength, but are far less expensive due to the greatly reduced materials costs. There are numerous applications in which plastics having a wide variety of mechanical properties, such as strength and stiffness, are appropriate and even desired over plastics having other strength and stiffness properties. Although the compositions having 95% by weight calcium carbonate are extremely brittle and have virtually no flexibility and minimum toughness, an example of an article that could be made therefrom is a “clay pigeon” or other frangible target used for target practice. The same biopolymer can formed using clay instead of calcium carbonate. The starch that is used can be any native starch. The starch, water and clay are blended in the same manner to form a starch melt into which is mixed various concentrations of clay. At lower concentrations of clay, the resulting material has increased tensile strength, toughness, and fracture energy. As the amount of clay is increased, the resulting discs become more brittle and fragile but also far less expensive. Such it could be used for a variety of purposes such as coasters to set drinks thereon, poker chips, targets, etc.

SPG1 is repeated in every respect except that pre-dried starch having an initial water content below about 1% by weight is used instead of native starch. The resulting melt formed from the starch, plasticiser and PCL does not require significant degassing to remove excess water vapor. SPG1is repeated in every respect except that a portion of the calcium carbonate is replaced with a zeolite that is capable of scavenging water in an amount such that a substantial portion of the water initially found within the native starch is absorbed by the zeolite and thereby removed from biopolymer. This allows for a greater tendency of the starch and PCL to undergo a condensation reaction in order to form a copolymer. The polycaprolactone can be replaced by a whole series of polymers and new biopolymers formed to the same recipies as above. Polymers used were: polyethylene ethylene-vinyl alcohol copolymer polylactic acid aliphatic-aromatic copolyester including 1,4-butandioladipinic acid and teraphthalic acid with a chain extender comprising isocyanate cellulose acetate cellulosic ether polyester polyamide polyvinylpyrillidone polyacrylic acid collagen sunflower protein soybean protein gelatin all of them gave good results. Any of the foregoing examples can be modified by including the following amounts of a fibrous component, such as a naturally occurring organic plant fibre: The fibrous component is blended within the biopolymer starch melt under conditions of sufficient shear so as to substantially homogeneously blend the individual fibres throughout the biopolymer starch melt. This occurs prior to the addition of the inorganic filler, which is thereafter blended within the mixture at lower shear. As the fibrous component is increased, the resulting biopolymer have increased tensile

strength, compressive strength, toughness, fracture energy, and modulus of elasticity. A wide variety of articles can be shaped from the foregoing compositions. Any of the foregoing examples is modified such that at least a portion of the low volatile plasticiser and/or water is replaced with one or more of the following plasticisers: propylene glycol 1,3-propanediol neopentylglycol sorbitol acetate DMSO polyvinyl alcohol (3-20 repeating units) polyethylene glycol polyglycerols (2-10 repeating units) The concentrations of the foregoing plasticisers are adjusted in order to yield a mixture of starch and plasticiser that is able to form a melt within a temperature range from as low as 70° C. to as high as 250° C. The above method for moulding starch is by means of forming that is known as "destructurized starch." In making destructurized starch, native starch or starch derivatives are mixed with a plasticizing agent and liquified under high temperature and pressure 9though normally the home experimenter only has high temperature available to them) in order to create a "hot melt" which is solidified by cooling the hot melt to below the "glass transition temperature." In this way, starch is treated like a biopolymer material. While destructurized or hot melt starch systems sound easy in theory, in practice the results are generally unsatisfactory and of low quality. Another method for moulding starch-based mixtures into articles involves moulding an aqueous starch mixture between heated dies. The starch binder is preferably initially in an unmodified, ungelatinised state within the mouldable aqueous mixture. Otherwise, the mixture would have to include far more water in order to maintain the same characteristics of mouldability due to the gelation of starch and the tremendous viscosity increasing effect of gelatinised starch within water. The starch water mixtures are heated between the moulds to a temperature great enough to gelatinise the starch as well as to remove the majority of the water from the moldable mixture. The resulting moulded articles can be demoulded, but are initially very brittle until they have been "conditioned" by placing them in a high humidity chamber for extended periods of time in order to reabsorb moisture. Simply demoulding the articles to have residual moisture has not proven feasible due to the tendency of the foamed cellular starch matrix to collapse if not sufficiently dried and hardened. However, obtaining a cellular starch matrix having sufficient

strength to avoid collapse usually entails overdrying the starch. Such a conditioning is a required after moulding process. One of the big problems with starch binders is that they are generally very sticky once dissolved or gelatinized in water. While this makes them generally good binding agents, it complicates the manufacturing process since sheets or articles made using large amounts of dissolved or gelated starch binders have a tendency to stick to the mould or sheet-forming apparatus. On the other hand, unmodified starch granules are generally insoluble in water and merely act as passive particulate fillers in wet systems unless the compositions containing starch granules are heated to above the gelation temperature of the starch. However, once gelated, the unmodified starch granules will, of course, become very sticky and tend to adhere to equipment, particularly heated equipment.

Biopolymer Starch Composites So, in order to distinguish the above simple starch based plastics from what we are going to discuss here I am going to refer to the plastic materials of this section as biopolymer starch composites. The biopolymer that we are going to discuss include, at a minimum, starch, a plasticiser, and a filler and we are going to look at how to make them and explore some of the possibilities of this material. A filler material doesn't have to be limited to inorganic mineral fillers like talcum powder you can also add fibres, synthetic polymers, and other things at the melt stage. The addition of fillers will changes the properties of the plastic at the melt stage as well as in the finished article. Filled, biopolymer can be shaped into a huge variety of things much like conventional biopolymer materials. Biopolymers can generally be described as comprising multi-component, multi-scale, micro-composites. By carefully incorporating a variety of different materials capable of imparting discrete, yet related, properties, it is possible to create a unique class or range of micro-composites having remarkable properties of strength, toughness, environmental soundness, mass-producibility, and low cost. Biopolymer starch composites are multi-component and what that really means that the biopolymer typically include two or more chemically or physically distinct materials or phases, such as the binding matrix comprising, at a minimum, a starch melt formed by starch with a plasticiser, a particulate filler and optional other additions, such as fibres for reinforcement, auxiliary polymers for added strength and water-resistance and void spaces for lightweight and/or insulation properties. Each of these broad categories of materials imparts one or more unique properties to the final biopolymer starch composite. Within these broad categories it is possible to further include different components such as, for example, two or more types of inorganic fillers, fibres, and synthetic organic polymers, which can impart different yet complementary properties to the biopolymer starch composites. What this means is that by adding different things to the composites you can quit remarkably change the characteristics. This allows for the specific engineering of desired properties within the final articles. It is really just a matter of experimenting by yourself to see what you get and the range of materials that you can experiment with is huge.

The multi-component (and hence, multi-property) nature of biopolymer is a significant departure from conventional materials, such as plastic, polystyrene, paper, or metal, which are essentially single component systems. For example, sheets, films, or moulded articles made from single component materials are generally limited to having the particular properties of the material from which they are made, sheets that are brittle generally cannot be bent or folded without damaging them, while films that are flexible are insufficiently rigid to provide other desired mechanical properties. In contrast, the multi-component nature of the materials of biopolymer allows for the introduction of multiple and/or specially engineered properties to allow for the manufacture of an almost endless variety of articles. This is one of those cases where the limit is set by your own imagination. We can think of biopolymer starch composites as being multi-scale. What this means is that the compositions and materials of the plastic are definable at different levels or scales. Specifically, within the biopolymer there is typically a macro-component composition in the range from about 10 nanometers to as high as about 10 mm, a micro-component composition in the range of about 1 micron to about 100 microns, and a submicron component. Although these levels can not be fractal, they are usually very similar to each other, and homogeneous and uniform within each level. In some cases, the materials can be reinforced with fibres. The term “fibre-reinforced” is self-explanatory, although the key term is “reinforced”, which clearly distinguishes the compositions from conventional paper or paper products. Conventional paper relies on a web, or intertwining of fibres, to provide the structural matrix and mass, as well as the binding, of the paper. However, the binding matrix in the starch plastic involves the interaction between the biopolymer starch phase, inorganic mineral filler component, optional fibres, and other optional components. The fibres act primarily as a reinforcing component to specifically add tensile strength, toughness, and flexibility but are not joined together like in a web to any substantial degree. Finally, the starch plastics can be seen as a micro-composite. What that means is that the biopolymer starch composites are not merely a compound or mixture but a designed matrix of specific, discrete materials on a micro-level, which are of different sizes, shapes, and chemical make-up. The materials are sufficiently well bound and interactive so that the unique properties of each are fully evidenced in the final composite (e.g., the tensile strength of the composition has a direct correlation to the tensile strength of the fibres and biopolymer starch phase). So, biopolymers can be combined with inorganic fillers and other components and moulded into a variety of products, including films, sheets, and moulded articles having properties similar to those of conventional biopolymer or paper materials. Articles made from them can be substituted for articles made from paper, plastic, polystyrene, and even metal. Films and sheets can be cut and formed (such as by bending, folding or rolling) into a variety of things. The next examples are mostly to give you an idea on how to form the starch-bound sheets based on the biopolymer starch composite idea. The examples are a couple of mix designs that you can clearly play around with as much as you like. Improved recipe 1

Sheets with a high starch content are prepared from mixtures that included the following components in the indicated amounts: ingredient

% by weight

Starch

18.5

water

66

Fibre

13

Methylcellulose

2.5

The fibre that was used in this example was southern pine and the unmodified starch was corn starch, which was ungelatinized when added to the mixture. The water, methylcellulose, and fibres were first mixed for 10 minutes in a kneader-mixer. Thereafter, the starch was added to the mixture, which was mixed for an additional 4 minutes. The mixture was spread onto a sheet of 30 cm×30cm and made about half a centimeter thick. The sheet was then heated to a temperature of about 100° C. in an oven in order to gelatinize the corn starch and the remove the water from the green sheet by evaporation. Improved recipe 2 Inorganically filled sheets having a high starch content were prepared from the following moulding composition. ingredient

% by weight

Starch

14

water

60

Fibre

10

Methylcellulose

2

Calcium carbonate

14

The water, methylcellulose, and southern pine fibres were first mixed for 10 minutes under high shear in a kneader-mixer. Thereafter, the calcium carbonate and corn starch were added to the mixture, which was mixed for an additional 4 minutes and then treat in the same way as above Improved recipe 3 Inorganically filled sheets having a high starch content were prepared from the following composition. ingredient

% by weight

Starch

11.5

water

46

Fibre

11.5

Methylcellulose

1

Calcium carbonate

28.5

Glycerine

1.5

The sheets were prepared in exactly the same way as above.

The Biopolymer Phase The terms “phase” and “phases”, when used in context with the biopolymer compositions refer to the discrete layers or compositional discontinuities within the biopolymer. The term “physical state” is used to refer to whether a material is a gas, liquid or solid. The term “biopolymer phase” is so defined because its plasticity, or ability to flow and be deformed, changes as a function of temperature. When heated sufficiently it flows, and when cooled sufficiently it become substantially solidified. The biopolymer is in a substantially solid state when cooled sufficiently below its melting point or softening range, and in a substantially liquid or semi-liquid state when heated sufficiently above the melting point or softening range. In general, whether the overall biopolymerare plastic or solid will usually be determined by the physical state of the biopolymer and not the other phases dispersed therein. Thus, when the biopolymer is heated to become plastic, the overall biopolymer will itself behave in a substantially plastic manner so that it can be shaped into a desired article of manufacture, even though it can contain solid particles or fibres dispersed in it. Similarly, when the biopolymer is cooled sufficiently so that it becomes resolidified, the overall biopolymer will behave as a solid rather than a flowable material, though it is possible for flowable liquids to remain encapsulated within the substantially solidified composition. In contrast to biopolymer, the solid phases and optional gaseous phases, dispersed throughout the biopolymer can not themselves undergo any change of physical state change during processing and moulding. Nevertheless, because the solid phase and optional gaseous phases are generally disperse phases comprised of discontinuous particles or bubbles, they can generally be considered to be passive constituents within the biopolymer matrix, although these particles and bubbles will often affect the physical and mechanical properties of the biopolymers. Because the solid and optional gaseous phases comprise relatively small particles or spaces within the continuous biopolymer phase, the overall biopolymer can act as either a solid or flowable material on a macro level though it can contain dispersed materials having different physical states on a micro level. The biopolymer also acts as a binding matrix that encapsulates the other phases and hold them together when biopolymers is in a solid state. Nevertheless, it should be understood that the other phases dispersed throughout the biopolymer will often

interact with biopolymer, both mechanically and chemically, in many cases. Some phases can simply act as passive constituents that interrupt biopolymer, while other phases can actually strengthen the composition by forming mechanical and/or chemical links between different regions of the composition on a macroscopic level. Other phases can primarily affect the density, flexibility, texture, and esthetic appearance of the composition rather than strength. In order to obtain the most beneficial effects from the various phases and components within the biopolymers, one of ordinary skill can select the components within the biopolymer that will maximize the synergistic effect between the various components in order to provide the best mechanical properties at the least cost. This process of properly selecting components having the best synergistic interaction can be referred to as “microstructural engineering”. The biopolymer includes, at a minimum, starch and a plasticiser that is capable of causing the starch to behave as a biopolymer material that can form a melt when heated rather than thermally decomposing. The biopolymer can also include one or more additional constituents that can improve the mechanical and/or chemical properties of biopolymer. In many cases, one or more additional biopolymer polymers can be added, such as a hydrophobic biodegradable polymer that will make the overall biopolymer less sensitive to fluctuations in ambient moisture. In addition, or in lieu of additional polymers, the biopolymer can include substances that chemically react with or physically associate with the starch in order to impart desired properties of e.g., strength and resistance to fluctuations in moisture, such as cross-linking agents, softeners, sealers, phase mediators or humectants. Still other constituents within the biopolymer can simply be solids, liquid, or gases that are dissolved or otherwise mixed throughout the biopolymer in a manner such that they are not thereafter identifiable as a phase that is significantly distinct from biopolymer. In the case where the biopolymer includes a synthetic or natural polymer in addition to the biopolymer starch fraction, the biopolymer will often contain two or more biopolymer subphases that are preferably substantially homogeneously mixed together but which nevertheless can constitute distinct subphases at the microscopic level. In a mixture of polymers, the polymer chains of one type of polymer will tend to associate with themselves rather than with the polymer chains of another type of polymer. In many cases, the two or more polymers will have varying degrees of hydrophilicity or hydrophobicity, giving them varying degrees of chemical compatibility. Just like water and oil, which are generally immiscible in each other and which tend to separate into distinct phases, so too will more hydrophilic polymers tend to resist blending with more hydrophobic polymers. Nevertheless, just like water and oil, which can be temporarily blended together through vigorous mixing conditions, so too can different polymers be blended together using high shear mixing conditions when heated to become biopolymer and, hence, Theologically compatible. Upon cooling to resolidify the biopolymer subphases, the polymers will remain mechanically mixed together in either a solution, as an interpenetrating network of polymeric subphases, or a combination of the two. Whereas water and oil will tend to separate into distinct phases over time, solidification of the blended polymers will, in essence, mechanically interlock the two or more different polymer subphases and prevent them from separating into larger, more distinct subphases.

The biopolymer generally comprises from about 10% to about 95% by volume of the biopolymer.

Biopolymers from cereals Interesting biopolymers can be prepared by combining a cereal grain with an organic solvent, in a grain:solvent parts by weight ratio of about 1:1 to 1:5, and for a time effective to extract a substantial proportion of the lipids from the cereal grain, mostly about 12 hours. After a suitable extraction period, the organic solvent and extracted lipids are separated from the cereal grain. A cross-linking agent is then reacted with the cereal grain by mixing the cross-linking agent with the organic solvent, and then combining the solvent/cross-linking agent mixture with the grain. The solvent-treated, cereal grain residue is washed with an amount of an organic solvent, or water, in order to remove the residual lipids, and unreacted cross-linking agent, from the residue. The residue is then dried, in an oven, to remove the residual solvent. To help moulding of the resulting dry material into a shaped article, the dried residue should be remoistened with an effective amount of water to provide a moisture content of about 5 to 30%. The cereal grain-based compositions can be formed into a desired article according to conventional processing techniques. For example, the composition can be shaped by compression moulding wherein direct pressure is applied using a hydraulic press; by injection moulding wherein an amount of the plastic composition in melted form is forced into a mould; by blow moulding wherein a tube of the biopolymer composition is extruded into a mould and air pressure is applied to the inside of the tube to conform it to the mould; and by other methods like rotation moulding, transfer moulding, extrusion moulding, vacuum forming, thermo-forming, pressure forming, and inflation moulding. The articles that are formed from the present compositions can be translucent in appearance and can have a high degree of mechanical strength, and water-resistance and are biodegradable but with improved water-resistance, particularly the articles formed from cross-linked compositions, so that the article will remain structurally intact for an extended period of time upon exposure to water. Although the articles made from the composition will degrade over time when exposed to moisture, such as from the atmosphere and the package contents, or from submersion in water or other direct contact with water, the articles of the invention, particularly those that include a cross-linking agent, have a higher resistance to such disintegration and will remain substantially intact for a more extended period of time than articles made from other starch-based biopolymers. An article made with a composition without a cross-linking agent will remain intact for about 1-3 days, and an article that includes a cross-linking agent will remain intact for about 5-7 days. Apart from being biodegradable, the compositions can be comprised entirely of components that are edible. I think that is cool. Solvent-Treated Corn Meal Biopolymers Prepared at Room Temperature

corn meal is suspended, in a sealed container, in an organic solvent (methanol or nhexane) at a 2:3 corn meal:solvent weight ratio. The mixture should be left to stand at room temperature (25° C.), without mixing, for 18 hours. The organic solvent is then filtered off from the cereal grain. The cereal grain residue is washed during filtering with an aliquot of organic solvent (methanol or n-hexane) in a 1:1 residue:solvent weight ratio. The residue is then dried in a convection oven at 50° C. for 16 hours. The dried residue was sprayed with water with mixing until the moisture content of the residue was 10.5 to 11.5% Solvent-Treated Corn Flour Biopolymers Prepared at Room Temperature corn flour made of particles that passed through a 60 mesh screen, which were smaller in size than the corn meal that was used in example above. The corn flour compositions are prepared as described in example above, except that the corn flour was also treated with ethanol or chloroform. Solvent-Treated Wheat Flour Biopolymers Prepared at Room Temperature Wheat flour is prepared according to the procedure in the example above, except that the flour was also treated with ethanol, n-hexane, or chloroform as the organic solvent. Solvent-Treated Semolina Biopolymers Prepared at Room Temperature semolina is prepared like in the example above, except that the cereal grain is treated with an organic solvent comprising absolute methanol or an aqueous mixture of a 1:1 volume-mixture of methanol and water. Ethanol-Treated Cereal Flours Prepared with Heat Corn meal, corn flour, wheat flour, semolina are separately suspended in an aqueous ethanol (95%) at 1:3 wt-ratio, and the mixtures are boiled for 2 hours with reflux and mechanical stirring. The mixtures are filtered using an aspirator to remove the solvent, and the residues are washed with ethanol (1:1 flour:ethanol ratio). The flour residues are dried, remoistened, and molded. Ethanol-Treated and Formaldehyde-Cross-Linked Cereal Flours Prepared at Room Temperature Corn meal, corn flour, wheat flour, semolina are suspended in an aqueous ethanol (95%) at a 1:3 flour:solvent weight ratio, and the mixture is heated at boiling temperature with reflux and mechanical stirring for 2 hours. The mixture is filtered using an aspirator to remove the solvent. The residue is mixed with a dilute formaldehyde solution (1% formaldehyde in 50% aqueous ethanol solution) at a 1:1 (solid weight) residue: formaldehyde solution weight ratio. The mixture is allowed to react without stirring for 24 hours at room temperature, and then excess formaldehyde is removed by washing the flour residue three times with 50% aqueous ethanol at a weight ratio of 1:1 solvent:flour per wash. The flour residue is then dried, remoistened and molded. Ethanol-Treated and Formaldehyde-Cross-Linked Wheat Flour Prepared at 50° C.

Wheat flour is treated with 95% ethanol and 1% formaldehyde according to the procedure in the corn meal example above, except that the cross-linking reaction with the formaldehyde solution is allowed to take place at 50° C. for 3 hours in a sealed container without stirring. Ethanol-Treated and Adipic Acetic Anhydride-Cross-Linked Wheat Flour Prepared at 50° C. Wheat flour is treated with 95% ethanol according to the procedure in the example ' Ethanol-Treated Cereal Flours Prepared with Heat', and cross-linked with 6 wt-% of an adipic acid-acetic anhydride mixture. The adipic acid-acetic anhydride mixture is prepared by dissolving 6 grams of adipic acid in 94 grams acetic anhydride. The adipic acid-acetic anhydride solution was diluted to 6% based on the dry weight of wheat flour, in 50% aqueous ethanol in a same total weight of the dilute as the flour, and the dilute was adjusted to pH 10.5 with a 10% sodium hydroxide solution. After the pH was adjusted, the ethanol-treated wheat flour was immediately mixed with the dilute, and the mixture was allowed to react at 50° C. for 3 hours without stirring in a sealed container. The pH of the mixture dropped to approximately pH 6.5 following the reaction. Excess adipic acid and acetic anhydride are removed by washing with 50% ethanol at a weight ratio of 1:1 per wash. The flour residue is dried, remoistened, and molded.

Cellulose Based Bioplastics. Cellulose acetate Oddly enough there is no generally accepted definition of "biodegradable" exists however what we seem to think we mean is that a material that substantially completely mineralizes over a period of less than about 10 years to primarily carbon dioxide, water, and sometimes methane or minerals commonly found in the environment is considered biodegradable. Preferably the material will substantially completely mineralize in less than about 5 years when held in soil or sea water containing natural microorganisms. The rate of mineralization depends on numerous factors including temperature, moisture and types of microorganisms present. In marine environments, the rate also depends on depth and flow rates of water as well as other algae or plants that can interfere with decomposition by attaching themselves to the plastics. Quite often the fillers which are present in the most plastics degrade at a slower rate than the plastic blends themselves. For example, some fillers from crustacean shells contain calcium carbonate and chitin which can tend to degrade slowly in comparison to starch-based plastics. Unique to cellulose acetates is the ability to control the rate of biodegradation through several factors. One is the amount of residual catalyst left in the material after synthesis. The usual material is sulfuric acid, whose presence in land fill or marine environments tends to cleave the acetate polymers faster and thus accelerate decomposition. The degree of acetyl substitution can also be controlled in reaction variables such as temperature and time profiles, wherein the degree can vary from 1.2 to 3 Further, after the reaction is finished, an aging step can be used to alter the

solubility of the acetate from chloroform to acetone soluble. By changing the crystalline form in this manner, along with other variables mentioned above, the rate of biodegradation in different environments can be controlled over very wide ranges. Acetate refers to any material usually naturally derived, wherein the dried material is reacted in the presence of glacial acetic acid, acetic or other anhydrides such as butyric or proprionic, and a homogeneous catalyst such as sulfuric acid. Blends of anhydrides can be used and blends of catalysts can also be used including sulfuric, hydrochloric and phosphoric acids. The degree of substitution is measured by the number or percent of acetyl groups which substitute for hydroxyl groups in the starting material. The percent substitution ranges from 20% to 60%. The degree ranges from 1.2 to 3 When the degree is near three, the material is called a triacetate. These materials are soluble in glacial acetic acid. Some are soluble in acetone or chloroform and most are insoluble in water. Some forms are slightly soluble in alcohols such as methanol or ethanol. Cellulose Acetates The basic production of cellulose acetate is as follows: Purified cellulose from wood pulp or cotton linters Mixed with glacial acetic acid, acetic anhydride, and sulphuric acid as a catalyst Aged 20 hours- partial hydrolysis occurs Precipitated as acid-resin flakes Flakes dissolved in acetone Solution is filtered More specifically: Add 20 milliliters of glacial acetic acid, 5 milliliters of acetic anhydride and three drops of sulfuric acid into a flask. The sulfuric acid is a catalyst for the reaction. Mix the ingredients with a glass rod. Place 0.5 grams of cotton into the flask. Ensure the cotton is fully submerged in the solution. Place the stopper lightly on the flask. The reaction takes about 8 hours and is complete when the cotton is fully dissolved. Gently pour the solution into a beaker containing 100 milliliters of distilled water. The cellulose acetate will precipitate out of solution, looking like clear filaments and globules in the water. Pour the water and cellulose acetate gel into a funnel containing filter paper. The cellulose acetate will collect on the filter paper. If doing this experiment in a laboratory, filtering is accelerated using a vacuum filter apparatus. Scrape the cellulose acetate off the filter paper into a test tube, using the glass rod. Add chloroform in the test tube to dissolve the cellulose acetate. Pour the dissolved

cellulose acetate onto a glass dish. Allow the chloroform to evaporate. The resulting thin film is cellulose acetate plastic. The reaction of cellulose in the presence of acetic anhydride yields a group of compounds called cellulose acetates, partially acetylated cellulose, which includes cellulose triacetates.These acetates differ in the degree that most do not have a sharp melting point and are insoluble in water and soluble in glacial acetic acid. These materials are used to make sheets, molded parts and fibres by mixing powders with various plasticisers. When blended with plasticisers, the melting points range from 130° C. to 240° C. In commercial production, they are mainly produced from cleaned cotton fibres and are sold on the basis of molecular weight, viscosity and degree of acetylation. Flour & Starch Acetates Acetates can also be synthesized from flours and starches. The way to make them is basically the same as for acetates made from cotton, with the exception that an aging period is not required once the reaction is completed. In general these acetates have an acetyl substitution ranging from 1.3 to 2.0, lower than for cotton. The viscosity for these materials is usually lower than for cotton based acetates. They have a final color of the dried powder ranging from tan to brown, with the exception of when pure low protein starches are used as starting materials. In this case the acetate can be white. Depending on the manufacturing process, these materials can have residual particles which are insoluble in glacial acetic acid. These can be removed by filtration or left in the reaction solution. The higher the particulate content, the lower the melt flow index of the final plastic. The function of these acetates in this invention is that starch and flour acetates can be substituted for cotton based cellulose acetates. The reasons for substitution include; modification of the melt flow index and viscosity, reduction in plastic cost when whole flour acetates are used, and the addition of color to the final product. Natural Fibre Acetates Natural fibres from sugar cane processing called sugar cane bagasse, and other natural fibres including kenaf, can be used in blends of cellulose acetates to provide increased structural strength or to reduce unit cost of the blended plastic. Fibre acetates are made in a similar manner to whole flour acetate with the exception that a milling step or series of sizing operations is required prior to reaction. The particle size depends on the starting material and its end use, but in general these fibres would be milled to a -10 mesh particle size. Reduction in particle size also permits a greater exposed surface area for acetyl substitution reactions and reduces the amount of sulfuric acid or other catalyst required in the acetylation. Given the sugar content of bagasse, the reaction products are dark brown. The yield of acetylated fibres ranges from 1.2 to 1.3 pounds of fibre acetate to 1.0 pound of initial dried fibre. The yield is lower than for flour, starch or cotton acetates since some materials are water soluble by products such as sugars and sugar acetates. The final fibres can be further milled to particle sizes ranging from -20 to -140 mesh. These natural fibre acetates are in the form of needles, in that the length to diameter ratio is usually higher than 10 and can be as high as several hundred. Long fibres can

plug the gates in injection moulding equipment. Thus, when in blended acetate plastics, these materials must be used in low weight loadings (less than 8%) and must be milled to small particle sizes, such as -50 mesh. Paper Acetates Wood pulp and recycled paper can also be used as starting materials for cellulose acetates. In the case of wood pulps, dried milled powders are used. In the case of paper acetates, the paper can be used whole (unprocessed) by shredding or the paper can undergo several processing steps prior to being dried and milled for conversion into acetates. Paper operations prior to reaction can include, shredding, ink removal, bleaching and other operations common in the recycled paper business. Paper acetates made from recycled paper are low in cost since the raw cellulose materials are less than $0.02/lb. However, due to the higher levels of porosity and acetic acid absorption, these materials require higher ratios of glacial acetic acid in the acetate reaction, as high as 10:1 acetic acid to paper, compared to 2:1 for cotton, starch or whole flour. This increases manufacturing costs by increasing the recycled acid streams in the processing plant. Paper acetates made from recycled newspapers wherein the ink is not removed are dark brown in appearance. When substituted for cotton based cellulose acetates and extruded, these materials form jet black plastic products. The black color is caused by residual inks and some oxidation within the extruder barrel since the powders contain a significant volume of trapped air. Depending on the method of manufacture, these paper acetates can be substituted for cotton cellulose acetates in a weight range of 1% to 40%. As the weight loading gets higher, the melt flow index decreases, making it more difficult to fill mold cavities with small diameters such as fork tines. Recipes Cellulose Acetate, Starch, Filler: In a glass beaker the following ingredients are mixed together: 1050 grams of cellulose acetate, 250 grams of corn starch, 220 grams of triacetin and 80 grams of a filler material that can be from any of sand, gravel, crushed rock, bauxite, granite, limestone, sandstone, glass beads, aerogels, xerogels, mica, clay, synthetic clay, alumina, silica, fly ash, fumed silica, fused silica, tabular alumina, kaolin, microspheres, hollow glass spheres, porous ceramic spheres, gypsum dihydrate, insoluble salts, calcium carbonate, magnesium carbonate, calcium hydroxide, calcium aluminate, magnesium carbonate, titanium dioxide, talc, ceramic materials, pozzolanic materials, salts, zirconium compounds, xonotlite (a crystalline calcium silicate gel), lightweight expanded clays, perlite, vermiculite, hydrated or unhydrated hydraulic cement particles, pumice, zeolites, exfoliated rock, ores, minerals, and other geologic materials. To be honest the list is endless. Try a few new ones yourself. The blend is then heated until it melts and mixed and cut into small pieces or cast into rods for later use. Cellulose Acetate, Starch. Propylene Glycol

In a glass beaker the following ingredients are mixed together: 230 grams of cellulose acetate, 60 grams of corn starch and 90 grams of propylene glycol. The blend is then heated until it melts and mixed and cut into small pieces or cast into rods for later use. Cellulose Acetate, Starch, Propylene Glycol, Shellac In a glass beaker, the following ingredients are mixed together: 213 grams of cellulose acetate, 102 grams of corn starch, 90 grams propylene glycol, and 4 grams shellac. The blend is then heated until it melts and mixed and cut into small pieces or cast into rods for later use. Cellulose Acetate, Starch, Propylene Glycol, Boric Acid In a glass beaker the following ingredients are mixed together: 210 grams of cellulose acetate, 100 grams of corn starch, 90 grams of propylene glycol and 4 grams of boric acid. The blend is then heated until it melts and mixed and cut into small pieces or cast into rods for later use. Cellulose Acetate, Starch, Propylene Glycol, Boric Acid, Gelatin In a glass beaker the following ingredients are mixed together: 170 grams of cellulose acetate, 140 grams of corn starch, 90 grams of propylene glycol, 5 grams of boric acid and 10 grams of gelatin. The blend is then heated until it melts and mixed and cut into small pieces or cast into rods for later use. Propylene glycol. Propylene glycol is considered Generally Recognized As Safe by the U.S. Food and Drug Administration, and it is used as an humectant (E1520), solvent, and preservative in food and for tobacco products, as well as being the major ingredient in the liquid used in electronic cigarettes (along with vegetable glycerine and, more rarely, PEG 400). It is also used in pharmaceutical and personal care products. Propylene glycol is a solvent in many pharmaceuticals, including oral, injectable and topical formulations, such as for diazepam and lorazepam that are insoluble in water, use propylene glycol as a solvent in their clinical, injectable forms. Like ethylene glycol, propylene glycol is able to lower the melting point of water, and so it is used as aircraft de-icing fluid.[4][7] It is similarly used as antifreeze in cars. Triacetin (Glycerol triacetate) Triacetin is an artificial chemical compound, commonly used as a food additive, for instance as a solvent in flavourings, and for its humectant function, with E number E1518. Boric acid You can make this by mixing borax with hydrochloric acid. It is used as an acne treatment and mild antiscptic. The dry powder is sold as an insecticide and is generally considered safe to use in household kitchens. It is often mixed with ethylene glycol as a wood preservative and is used in the manufacture of silly putty.

Regenerated cellulose plastic. The main problem with a regenerated cellulose plastic is in dissolving the cellulose in the first place. Sodium hydroxide based systems are promising because they can lead to an environmentally friendly, simple nad economic process. Celllulose can be dissolved in aqueous sodium hydroxide solutions at low temperatures and at low concentrations (7-10% NaOH at -5 to -6). However it is pretty difficult to do so with a single alkali. In contrast a NaOH/Urea can dissolve cellulose. 4g of cellulos (Cotton being good) is dissolved in 48g of 14% by weight NaOH solution precooled to zero degrees centigrade and stirred for 1 minute. Then 48g of 24% by weight urea precooled to zero is added in one go and stirred for 2 minutes and the cellulose will disolve. Pour the solution onto a glass plate and immerse it in a 5% sulphuric acid solution at 25 degrees for 5 minutes to coagulate and regenerate the cellulose. After 5 minutes wash the film and air dry. When it is dry you will get a clear cellulose film. The film will shrink unless you fix it at the edges to stop it doing that. Cellulose nitrate. Cellulose nitrate is a highly flammable compound formed by nitrating cellulose through exposure to nitric acid. It was originally known as guncotton. Cellulose nitrate is plasticized by camphor and was used by Kodak, and other suppliers, from the late 1880s as a film base in photograph, X-ray films and motion picture films; and was known as nitrate film. The use of nitrocellulose film for motion pictures led to the requirement for fireproof projection rooms with wall coverings made of asbestos. The US Navy shot a training film for projectionists that included footage of a controlled ignition of a reel of nitrate film, which continued to burn when fully submerged in water. Unlike many other flammable materials, nitrocellulose does not need air to keep burning as the reaction produces oxygen. Once burning, it is extremely difficult to extinguish. Immersing burning film in water can not extinguish it, and could actually increase the amount of smoke produced. Due to public safety precautions, the London Underground forbade transport of movies on its system until well past the introduction of safety film. Consequently, although it is a bioplastic, it's use is limited and the making of it and storing of it particularly dangerous - so this note is all I will say on this matter. Viscose. Viscose is a solution of cellulose xanthate made by treating a cellulose compound with sodium hydroxide and carbon disulfide. Byproducts include sodium thiocarbonate, sodium carbonate, and sodium sulfide. The viscose solution is used to spin the fiber viscose rayon, or rayon, a soft man-made fiber commonly used in dresses, linings, shirts, shorts, coats, jackets, and other outer wear. It is also used in industrial yarns (tyre cord), upholstery and carpets. The use of viscose is declining, in part because of the environmental costs of its production.

Sugar based Polymers Poly Lactic Acid

Polylactic acid is a biopolymer aliphatic polyester derived from renewable resources, such as corn starch, tapioca roots, chips or starch or sugarcane. Toy pastes of the "modeling paste" type, which are essentially designed to be made into a particular shape by the child in order to represent people and/or objects, are already known; these pastes are made from products of mineral origin, forexample, clays or products derived from clay, or alternatively from products of vegetable origin of the crosslinked starch type. A crude form of PLA can be produced by simply heating powdered lactic acid with powdered stannous chloride - commonly used in pottery glazes - in a test tube. Poly Glycolic Acid Polyglycolide or Polyglycolic acid (PGA) is a biodegradable, thermoplastic polymer and the simplest linear, aliphatic polyester. It can be prepared starting from glycolic acid by means of polycondensation or ring-opening polymerization. PGA has been known since 1954 as a tough fiber-forming polymer.

Seaweed Based plastics Common Polysaccharides in Marine Seaweeds Seaweed is a loose colloquial term encompassing macroscopic, multicellular, benthic marine algae. Commonly they are split into three groups, the green, red and brown algae. Floridean Starch Floridean starch is a special type of starch that is primarily found in red seaweeds but it can also be found in green ones. It acts as the major cellular storage units of molecules and energy in these organisms. This type of starch is said to be threedimensional in structure and the polysaccharide is sulfated. Floridean starch is found in the cytoplasm of the cell unlike true starch which is found in the chloroplast. To extract Floridean starch, one usually boils the seaweed in water until particles settle at the bottom. Agar Agar is a cell wall constituent of red algae. It is a natural polymer made from repeating units of galactose. It is an odourless, slightly transparent and sugar-reactive substance which takes the form of a gel. Unlike gelatin which is a protein-based gel derived from animals, agar is a polysaccharide extracted primarily from red seaweeds To extract agar, the red seaweed is cooked in 5% NaOH solution for an hour. It is then washed with running water and soaked in a 0.5% acetic acid solution for an hour. It is washed again and soaked in one litre of boiling water. It is then blended and filtered. The filtrate is collected and put in a freezer overnight. The following day, the gel is thawed and the agar wafer is dried Alginate

Alginate is a cell wall constituent of brown algae. It is a natural polymer made from repeating units of mannuronic acid and guluronic acid. It is an odorless, slightly transparent and viscous gum which takes the form of a liquid gel. It has a hydrophilic nature that makes alginate capable of absorbing water much greater than its weight. To extract alginate, the brown seaweed is soaked in 0.1 M HCl solution overnight. The seaweed is then washed in 1% Na2CO3 solution. Then it is blended and filtered. The filtrate is collected and precipitated with Isopropanol (that's rubbing alcohol to you and me - you can get it from a chemists - you use three times the volume of the filtrate). Finally, it is dried and ground. These polysaccharides from seaweeds particularly agar and alginate are widely used particularly in the fields of food technology, biotechnology, microbiology and medicine. Their water absorbent capacities are used as thickening, emulsifying and stabilizing agents in confectionaries and pastries like ice creams and jelly-aces. Agar is used in gel electrophoresis and as a growth medium for microorganisms. Alginate is used in making fibres for band aids and fireproof outfits. Floridean starch is still being researched for its probable applications in the industry Simple biomass-based plastic resins from different combinations of natural algal polysaccharides are easy to make and simple formulations would be: 1.3 g agar 5 mL glycerol 30 mL distilled water

2.3g alginate 5 mL glycerol 30 mL distilled water

3.3 g carrageenan 5 mL glycerol 30 mL distilled water

1.5 g agar 1.5 g alginate 5 mL glycerol 30 mL distilled water

1.5 g agar 1.5 g carrageenan 5 mL glycerol 30 mL distilled water

1.5 g alginate 1.5 g carrageenan 5 mL glycerol 30 mL distilled water

1 g agar 1 g alginate 1 g carrageenan 5 mL glycerol 30 mL distilled water

The following bioplastics from different combinations of seaweed polysaccharides and fillers can also be made.

6 g Floridean starch 5 mL glycerol 5 g plaster of Paris 60 mL distilled water

6 g agar 5 mL glycerol

5 g plaster of Paris 60 mL distilled water

6 g alginate 5 mL glycerol 5 g plaster of Paris 60 mL distilled water

3 g Floridean starch 3 g agar 5 mL glycerol 5 g plaster of Paris 60 mLdistilled water

3 g Floridean starch 3 g alginate 5 mL glycerol 5 g plaster of Paris 60 mLdistilled water

3 g agar 3 g alginate 5 mL glycerol 5 g plaster of Paris 60 mL distilled water

2 g Floridean starch

2 g agar 2 g alginate 5 mL glycerol 5 g plaster of Paris 60 mL distilled water Bearing in mind the comments from previous examples the order of the day here is experimentation. The range of plastics available based on these simple recipes are as broad as your imagination. The filler can be substituted with starches and glycerol by sorbitol. The procedure is basically the same in every case. Mix all of the ingredients together in the amounts above, and stir. Keep mixing until there are no clumps and it is as dispersed as it's gong to get. Then heat the mixture to 95 C or to when it starts to froth (whichever comes first). Stir the mixture while you are heating it, and once it is at the right temperature (or starts to froth), remove the heat and keep stirring. Scoop out excess froth with a spoon, and make sure there are no clumps. Carefully pour the mixture into a drying pan, and make sure to spread it out to let it dry. How long it takes will depend on the temperature and humidity in the room, and it may take several days (depending on your formulation). You won't be able to remove the plastic from the drying sheet easily until it is completely dry,

Chitin Chitinis a long-chain polymer of a N-acetylglucosamine, a derivative of glucose, and is found in many places throughout the natural world. It is the main component of the cell walls of fungi, the exoskeletons of arthropods such as crustaceans (e.g., crabs, lobsters and shrimps) and insects, the radulas of mollusks, and the beaks and internal shells of cephalopods, including squid and octopuses. In terms of structure, chitin may be compared to the polysaccharide cellulose and, in terms of function, to the protein keratin. Chitin can be extracted from the common button mushroom, agaricus bisporus, that's the one every supermarket in Britain sells. The preparation proceedure is shown in the following flow chart.

The chitin can be obtained from these mushrooms by the series of purification and chemical treatments shown above that remove the associated components, that is the proteins, pigments, glucans, and minerals. The procedure and treatments are as follows. At the first stage, sodium hydroxide is used to dissolve, hydrolyze, and remove the proteins and alkali-soluble glucans. Hydrochloric acid is then added to remove the minerals. At this stage, that the partial neutral saccharides and acid-soluble protein compounds are also separated. The extraction step with sodium chlorite and acetic acid bleaches out the pigments. For the final stage, the sample is treated with sodium hydroxide again to eliminate and remove any residual glucans, including trace amounts of proteinsthen it is dried. The drying process causes strong hydrogen bonding between chitin fibers..So, the sample should be kept wet.The extracted

sample with 1 %w/w of chitin is then ground down with a pestle and morter in the presence of acetic acid. The cationization of a small portion of amino groups on the chitin fiber causes electrostatic repulsion, which facilitate the mixing. After the grinding treatment, the chitin slurry had a high viscosity. There is about 3% chitin in each mushroom. A glucan molecule, incidently, is a polysaccharide of D-glucose monomers. You could try and make a plastic from this. Chitosan is a linear polysaccharide composed of randomly distributed β-(1-4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). It is made by treating chitin with sodium hydroxide. Basically you ix 1g of chitin with 30mL of 50% NaOH solution, heat and stir for 60 minutes and you are done.

Protein Starch Composite Plastics. As people have become more aware of environmental pollution caused by plastics. more efforts have been made in developing biodegradable plastics, such as proteinbased plastics and starch based plastics. In the 1930-1940's and 1980's, protein and starch were used as a "filler" with conventional petroleum-based thermoplastics which made it possible to decrease the raw material cost or make it easier for them to biodegrade. However, a continuing problem of protein and starch based plastics is water resistance and poor aging properties. These plastics tend to absorb water over time, which interacts with the protein or starch weakening its mechanical properties. In other words, they degrade too quickly. Articles made from protein or starch plastics usually have good initial mechanical properties, but do not last more than a month or two. Pure protein has poor flowability, but it can be improved by compounding with starch. Starch products are brittle with poor physical aging, but they can be improved by compounding with protein and chemical modification. The flexibility of protein/starch compositions can be enhanced by the aid of plasticizers and chemical modification, but the glass transition temperature of such protein/starch composition is decreased. The use of natural cellulosic fiber as reinforcement in protein/starch compositions reduce the overall composition cost, and also enhance toughness, thermal and strength properties. The basic ingredients of these types of plastic are: a protein a starch a plasticiser a metal salt a filler The protein used in these kinds of protein/starch compositions can be either plant or animal derived protein material. Soy protein is a good source of plant derived protein.

Other plant derived protein includes gluten (such as wheat, oat, or rice gluten), corn zein, hordein, avenin, kafirin, or a combination of them. Suitable animal derived protein includes casein, albumin, collagen, gelatin, keratin, or a combination. The starch used in the protein/starch compositions can be native (unmodified) starch, chemically modified starch, pregelatinized starch, or a combination. Typical native starches can include corn starch, including maize, waxy maize, and high amylose corn starch, potato starch, sweet potato starch, wheat starch, rice starch, tapioca starch, sorghum starch. The starch may be a normal starch (about 0 to 30 wt. % amylose) or a high amylose starch (greater than about 50 to 70 wt-% amylose). The amount of starch (wt. %) combined with the protein is usually about 20 to 50 wt. %. Plasticizers improve the processing, flowability, and enhance flexibility of the protein/ starch/natural cellulosic fiber compositions. An effective amount of plasticizer is about 5 to 25 wt. %, preferably about 15 to 25 wt. %. Typical plasticizers which can be used in the present compositions include polyols and high molecular weight alcohols, such as glycerol, ethylene glycol, 1,3-propanediol, propylene glycol, sorbitol, sorbitan, mannitol, diglycerol, butanediol, and urea. Glycerol and propylene glycol are currently preferred plasticizers. The esters of polyols, such as glycerol monoacetate and glycerol diacetate can be used as an auxiliary plasticizer as well. The metallic salt hydrate included in the compositions can be calcium, sodium, potassium, zinc, iron, aluminum or phosphorus salts or a mixture thereof. The metallic salt hydrate can also be chloride, carbonate, sulfate, nitrate, lactate, oxalate, or acetate salts Natural cellulosic fiber can be used as a reinforcing filler. Natural cellulosic fibers enhance physical properties, such as tensile strength, compression strength, rigidity modulus, improve heat insulation property, and reduce shrinkage and deformation of the products in processing and use. Typical natural cellulosic fibers used in the present invention include grass fibers, wood fibers, chopped straw, chopped corn straw, bagasse, cotton fibers, chopped leaves, chopped corn husks, hemp fibers, and cellulosic fiber made of other natural plants and their derivatives. Recipes Simple type protein 100g starch 400g glycerol 50g water 200g talc 6g calcium carbonate 5g mix together, need then heat to 98 degrees C for 5mins while putting iit under pressure.

Fibre type protein 100g starch 70g glycerol 40g water 70g Fibre 70g talc 3g calcium carbonate 2g mix together, need then heat to 98 degrees C for 5mins while putting iit under pressure. Extracting Gluten from flour Step 1 - Knead the Wheat/Water Use one part water to two parts flour. Combine water and flour in your bowl, and knead for four minutes in your. Add another litre of water and knead one more minute. This quickens the separating of the gluten from the starch and bran. place it in a wet plastic bag and beat it with the broad side of a mallet for four minutes. Step 2 - Separate the gluten from the starch and bran Set your bowl with the dough in the sink and fill it with tap water. Next to it, put a bowl with 2-3 litres of water in it. Place an empty bowl off to the side. With both hands, squeeze the dough through your fingers until it starts coming apart in shreds. Take handfuls of dough at a time and squeeze and turn it to wash out the starch and part of the bran in the second bowl. This bowl will be catching your starch and bran. When the gluten feels as elastic as chewed bubblegum and barely grainy, place it in the empty bowl. That is your raw gluten. Continue until you have gone through all of the dough. Step 3 - Bake & grind for quick use Spread the gluten by patting it out onto a board and cutting it into 1" stripsand let it dry.

Oat Based plastics Oats have numerous uses in food; most commonly, they are rolled or crushed into oatmeal, or ground into fine oat flour. A class of polysaccharides known as beta-D-glucans comprise the soluble fibre in oats.

Beta-D-glucans, usually referred to as beta-glucans, comprise a class of indigestible polysaccharides widely found in nature in sources such as grains, barley, yeast, bacteria, algae and mushrooms. In oats, barley and other cereal grains, they are located primarily in the endosperm cell wall. Oat beta-glucan is a soluble fibre. It is a viscous polysaccharide made up of units of the monosaccharide D-glucose. Oat beta-glucan is composed of mixed-linkage polysaccharides. This means the bonds between the D-glucose or D-glucopyranosyl units are either beta-1, 3 linkages or beta-1, 4 linkages. This type of beta-glucan is also referred to as a mixed-linkage (1→3), (1→4)-beta-D-glucan. The (1→3)-linkages break up the uniform structure of the beta-D-glucan molecule and make it soluble and flexible. In comparison, the indigestible polysaccharide cellulose is also a beta-glucan, but is not soluble. The reason it is insoluble is cellulose consists only of (1→4)-betaD-linkages. Oats are also the only cereal containing a globulin or legume-like protein, avenalin, as the major (80%) storage protein. Globulins are characterised by solubility in dilute saline. The more typical cereal proteins, such as gluten and zein, are prolamines (prolamins). The minor protein of oat is a prolamine, avenin. Both of these are relatively easy to extract by cooking the oats in an excess of water and filtering the meal after it has cooked. Reducing this down gives you a biopolymer that can be used in much the same way as any of the above polymers.

Where To Go From Here? It should be obvious by now that despite the simplicity of the formula: biopolymer + plasticiser + other additives = bioplastic the variety is enourmous. The sources of the biopolymer are vast and greatly effect the outcome of the plastic, the plasticisers available are huge and the other additives beyond count. The only place to go from here it experimentation and once you get started on developing bioplastics the method is almost addictive as you begin to wonder what else can be used. Who knows what you will find - good luck!

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