Handbook of Plastics Technologies Part 15 ppt

PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS 8.87 dation were equally unclear. This brought the initial generation of “biodegradable” plastics, which most often were mixtures of starch with low-density polyethylene. As time went on, information increased about both the behavior and composition of solid waste in landfills. It became clear that the majority of material in landfills was, in fact, biodegradable, consisting of paper, food waste, and yard waste (see Fig. 8.4). There- fore, if biodegradation was the solution to landfill problems, there should be no problem! However, studies of landfill behavior showed clearly that, when landfills are kept dry, as is required by regulations designed to help prevent groundwater contamination, degradation is a very slow process, taking decades or more to be complete. Hence, simply making the plastics in a landfill biodegradable was not a real solution when conditions prevent rapid microbial destruction of landfilled materials. Furthermore, calling a plastic “biodegradable” on the basis of loss of tensile strength, or even complete loss of structural integrity, is questionable at best. The starch/polyethylene bags may disappear from view when the starch fraction is metabolized by microorganisms, but this is no guarantee that there has been any substantial change in the polyethylene fraction of the bag. The current view is generally that complete biodegradation means complete destruction of the molecular structure, a “return to nature” of the carbon content of the polymer rather than conversion of a plastic item to unidentifiable plastic powder. Implicit in labeling a polymer biodegradable is the assumption that this molecular destruction will take place in some “reasonable” time frame. Even the most recalcitrant plastic will probably biodegrade eventually—but eventually may mean centuries. Obviously, such slow biodegradation is of no practical value in the short term. In recent years, there has been some tendency to stay away from terms like “biodegradable” that are fraught with uncertainty in meaning. Rather, plastics may be labeled “compostable” if they meet requirements set by national or international standards for this designation. Any material that is compostable is almost always biodegradable, but the reverse is not necessarily the case. Another designation for plastics that is drawing increasing interest is sometimes re- lated to, but by no means identical to, biodegradable. Biobased plastics are those that are formed from natural renewable feedstocks rather than fossil fuels. Biobased plastics may or may not be biodegradable (or compostable), and vice versa. In January 2005, the U.S. Department of Agriculture began setting guidelines for designating items made from biobased products that will be given preference in federal purchasing programs, much as products with recycled content are given preference. Plastics may undergo a variety of other types of degradation. Of particular interest in the context of this discussion are photodegradation and hydrolytic degradation. Photodeg- radation is degradation that occurs as a result of exposure to light, generally ultraviolet ra- diation that is part of sunlight. During the 1980s, some plastics labeled “degradable” as a marketing tool were photodegradable rather than biodegradable. Photodegradation can be an important attribute for plastics that are frequently littered, but is of little or no value for plastics that are landfilled or composted. Hydrolytic degradation is degradation through the action of water, usually involving chemical reactions of the polymer with water, often in reactions that essentially reverse the polymerization process. A number of the commercially important biodegradable plastics degrade in part by hydrolysis. In some cases, the polymers are not biodegradable until they have first hydrolyzed enough to significantly reduce their molecular weight, making them susceptible to microbial attack. As has been mentioned, degradation of plastics, as is the case for other materials, is af- fected by the conditions to which the plastic is exposed. Sunlight, mechanical stress, temperature, and humidity all affect the degradation rate. The practical value of biodegradable plastics is a subject of some debate. As discussed, in a landfill, even foods degrade slowly, a fact amply illustrated by photographs that have Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS 8.88 CHAPTER 8 been presented of grass, carrots, chicken, and other products still readily recognizable after ten years or more in a landfill. 349 Therefore, there is little value in using biodegradable plastics if a landfill will be their eventual destination. Nonetheless, some users perceive value in the use of biodegradable plastics as part of a “green” image for the company. This is especially true, for example, for products that are marketed as organic. Composting, in contrast, is designed to accelerate biodegradation and serve as an alternative to landfilling. Use of biodegradable plastics permits disposal through composting and therefore can reduce the burden on landfill if systems to direct the product or package to composting are in place and utilized. In addition, for products that pose a litter problem, the use of biodegradable plastics can greatly reduce their prevalence and longevity in the environment. This can be of particular value for plastics that may reach water systems. Plastics in the marine environment are a significant problem. Even plastics improperly dis- posed of on land can eventually reach the ocean, where they pose significant problems to sea turtles and other marine life. Unfortunately, some compostable plastics do not biodegrade quickly in water, as they require the elevated temperature of a compost pile to cause sufficient hydrolysis to start the degradation process. One way to structure composting programs that may accept biodegradable plastics is through curbside collection of a compostable fraction of waste, often termed wet organics. Such programs generally collect food wastes, yard wastes, and food-contaminated paper. Biodegradable plastics can also be accepted in such programs, at least in theory. (In prac- tice, there may be concerns about the ability of individuals to discriminate properly between biodegradable and nondegradable plastics.) Biodegradable bags for collecting these organic wastes are already a substantial market in Europe. In the United States, composting is limited almost entirely to yard waste. Food wastes are composted primarily in special programs targeted at institutions such as food-processing facilities, restaurants, and cafeterias. Recently, a few communities have started to institute residential composting programs. One of the first was in San Francisco, where what started as a pilot program in a few neighborhoods has now gone citywide and is expanding to neighboring communities. Freedonia forecasts that demand for biodegradable/compostable plastics will grow more than 16 percent per year between 2004 and 2008, reaching a total of over 290 million pounds in 2008. 350 In Europe, composting has a much longer history and is more highly developed. The first composting plants for mixed municipal solid waste date to the 1970s. Collection of wet organics is commonplace in many countries. Expansion of composting is being driven by regulations requiring a reduction in landfilling of biodegradable municipal wastes. By 2006, the amount must be reduced to 75 percent of 1995 levels; additional targets culmi- nate in reduction by 2016 to 35 percent of those levels. 351,352 With fees for nonbiodegradable plastics to ensure their collection and recycling, it is easier for compostable plastics, which generally cost more per pound, to compete economically. In part for this reason, interest in compostable plastics for European markets is generally greater than for U.S. markets. Canada also is actively increasing composting as a disposal alternative. BASF, Cargill Dow, Novamont, and Rodenburg Biopolymers, in November 2004, signed a ten-year Environmental Agreement with the European Commission, committing themselves to using biodegradable and compostable polymers in the manufacture of packaging materials. The agreement includes a certification plan for quality control, and a labeling plan to facilitate waste handling. It will be managed by the International Biodegradable Polymers Association & Working Groups (IBAW). These four companies are estimated to represent more than 90 percent of the European market for biodegradable plastics and a similar share of the global market. As of mid 2005, supermarket carrier bags and bags for collection and composting of food waste were estimated to consume 38 percent of all biodegradable plastics. 353 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS 8.89 One concern that is frequently raised about degradable plastics is their effect on plastics recycling. As we have seen, in recycling, separation of plastics by resin type is key, at least for most high-value applications. If adequate separation is achieved, biodegradable plastics should not adversely impact recycling. Some biodegradable plastics can themselves be recycled if an infrastructure for doing so is developed. As a practical matter, it is unlikely that sufficient quantities will be available to make it worth setting up such systems, at least in the short term. Of course, some argue that composting itself is “nature’s recycling.” To the extent that biodegradable/compostable packages compete with alterna- tives that would be otherwise recycled, there is the additional issue of whether recycling or composting is more environmentally beneficial. A full answer to this question, which would require a thorough life-cycle assessment, is not available. Certainly it will be im- pacted by actual recycling rates and very possibly by local variables such as water avail- ability, energy mix used for both corn (or other feedstock) cultivation and conversion and for plastic production, types and quantities of herbicides used, and a multitude of other variables. Various organizations have issued standards for determining the biodegradability or compostability of plastics. For example, in Europe, EN 13432 describes methodology for evaluating the compostability of a polymer. In the United States, the Biodegradable Prod- ucts Institute certifies materials that meet its requirements, and, in combination with the U.S. Composting Council, award their “Compostable Logo” to qualifying products. Japan’s system for testing and certification of biodegradable plastics is GreenPla, managed by the Biodegradable Plastics Society. ASTM D6400, “Standard Specification for Compostable Plastics,” is another commonly used evaluation procedure. There is ongoing international effort to standardize policies and procedures for certifying biodegradable products. 354 Biodegradable plastics can be categorized in a number of ways. They can be divided into synthetic plastics and natural plastics, into biobased and nonbiobased plastics, or by polymer family. The reported chemical compositions of various biodegradable plastics, as compiled from various sources, are shown in Table 8.7. 355–358 It should be noted that cellophane, the first transparent packaging material, is biodegradable, but it and other biodegradable cellulosic materials (such as paper) are not included in this discussion because they are not plastics. Biodegradable plastics designed primarily for medical applications, personal hygiene products, agricultural products, tex- tiles, and so on also are not included. 8.19.2 Starch-Based Plastics and Other Polysaccharides 8.19.2.1 Starch-Based Plastics. As can be seen in Table 8.7, a variety of starch-based plastics have been produced by several companies. Starch-based plastics are often water- soluble as well as biodegradable. Some contain almost entirely starch; others contain blends of starch with other biodegradable components. An early producer of all-starch biodegradable plastics was Warner-Lambert. In 1990, it produced what was claimed to be the first biodegradable plastic from starch and sold it under the tradename Novon. The polymer contained about 70 percent branched starches and 30 percent linear starch, along with a glyceride as a plasticizer. In 1993, Warner-Lambert suspended operation of Novon after trying unsuccessfully to sell the business. In 1995, EcoStar International acquired the technology and formed Novon International, which soon thereafter was acquired by Churchill Technology. In 1996, Churchill Technology filed for bankruptcy, and production of Novon stopped. StarchTech, Inc., of Golden Valley, MN, sells biodegradable starch-based resins for injection molding and other processes and licenses their technology to other producers. One Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS 8.90 CHAPTER 8 TABLE 8.7 Reported Composition of Selected Biodegradable Plastics *355–358 Polymer category Trade name Manufacturer Starch Mater-Bi Novamont Cellulose acetate Acetate cellulose CelGreen Eco-Excel Fasal Lunare Natureflex Teijin Daicel Chemical Industry Ebara Jitsugyo Co. (EJ CO) IFA Nihon Shokubai Innovia Films Cellulose acetate/polyethylene succinate EnviroPlastic Planet Polymer Technologies Chitosan Dolon Aicello Chemical (Aicello Kagaku) Polybutylene adipate copolymer Bionolle Ecoflex EnPol Showa Highpolymer BASF Ire Chemical Polybutylene succinate Bionolle SkyGreen BDP Showa Highpolymer SK Polymers Polybutylene succinate copolymer Biomax Bionolle Eastar Bio Ecoflex EnPol Iupec DuPont Showa Highpolymer Novamont (was by Eastman Chemical) BASF Ire Chemical Mitsubishi Gas Chemical Polycaprolactone CAPA CelGreen Tone Solvay Daicel Chemical Industry Dow (was Union Carbide) Polycaprolactone copolymer Celgreen Daicel Chemical Industries Polyester, aliphatic-aromatic Eastar Bio Ecoflex Eastman Chemical Co. (Novamont) BASF Polyester carbonate IUPEC Mitsubishi Gas Chemical Polyethylene sebacate Eternacoll Ube Industries Polyethylene succinate Lunare Nippon Shokubai Polyethylene succinate copolymer Lunare Nippon Shokubai Polyethylene terephthalate copolymer Biomax Green Ecopet DuPont Teijin Polyhydroxyalkanoate Nodax Pullulan Procter & Gamble Hayashibara Co Polyhydroxybutyrate and copolymers Biogreen BioMer Biopol PHBH, Nodax Mitsubishi Gas Chemical Biomer Metabolix Kaneka Corp. Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS 8.91 Polylactic acid EcoPla Hycail Lacea Lactron Lacty (Lacti) NatureWorks Toyota Ecoplastics Vyloecol Cargill Dow Polymers Hycail Mitsui Chemicals Kanebo Gohsen Ltd. Shimadzu Cargill Toyota Motor Corp. Toyobo PLA blend Bio-Flex Nature Compounds (FKuR Kunststoffe) PLA copolymer GS Pla Mazin Plamate Vyloecol Mitsubishi Chemical Gemplus, U. of Nebraska Danippon Ink & Chemicals Toyobo Polysaccharide Pullulan Hayashibara Co. Polytetramethylene adipate co terephthalate Eastar Bio Chemitech (Novamont) Polyvinyl alcohol based Aquarto Dolon Ecomaty, Gosenol Enpol Elvanol Erkol Hydrolene J-Poval Kuraray Poval, Kuraray Exeval, Kuralon MonoSol Polinol Poval Planet Polymer Technologies Aicello Chemical Nihon Gohsei Kagaku Kogyo (Nippon Synthetic Chemical) Polyval DuPont Erkol Idroplast Japan VAM & Poval Kuraray MonoSol Div. of ChrisCraft DC Chemical Co. ShinEtsu Chemicals, Kureha (Kuraray) Starch-based BIOPar Bioska Clean Green Cohpol Cornpol Earthshell Eco-Foam Eco Ware Envirofil EverCorn Flo-Pak Bio Greenfill BIOP Biopolymer GmbH Plastiroll Oy Clean Green Packaging, StarchTech VTT Chemical Technology Japan CornStarch EarthShell Corp. American Excelsior Co. Nissei EnPac (DuPont & ConAgra) Evercorn (Japan Corn Starch & Grand River Technology) Marfred Industries, Free-Flow Packaging Corp. Green Light Products Ltd., Heygates TABLE 8.7 Reported Composition of Selected Biodegradable Plastics *355–358 (Continued) Polymer category Trade name Manufacturer Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS 8.92 CHAPTER 8 of their products is Clean Green Packing. 359 American Excelsior, headquartered in Arling- ton, TX, manufactures several starch-based plastics, including Eco-Foam loose fill and sheet and laminated structures. These materials also are water soluble as well as biodegradable. 360 Novamont makes Mater-Bi, another starch-based biodegradable polymer. This material is widely used for bags for collection of organic wastes for composting. Novamont claims programs serving over 15 million people use Mater-Bi bags and carriers for collection of organic wastes and grass clippings. 361 Biotec is a German producer of starch-based polymers. In mid 2005, it announced plans to expand its production capacity from 2000 tonnes per year to 12,000 tonnes per year within the next 6 months, with the announcement of acquisition by Stanelco. Stanelco makes radio-frequency welding equipment and pioneered RF technology used to seal starch-based polymers without overheating or burning. Stanelco also recently acquired Adept Polymers, a manufacturer of water-soluble polymers. 362,363 Stanelco uses Biotec products to make food trays, air pillows, and edible packaging. The company hopes to bring the price for starch-based sheet for thermoforming down to less than 10 percent more than competitive PET sheet. 364 EarthShell Corp. uses a combination of starch and limestone to make packaging products that are biodegradable and compostable. Products manufactured include cups, plates, bowls, sandwich wraps, and hinged-lid containers. The company’s foam laminate is produced by mixing the starch and limestone with water and fiber and placing it in a heated mold. Vaporization of the water foams, forms, and sets the product. The material physi- cally disintegrates in water when it is crushed or broken. 365 Freedonia predicts demand for starch-based plastics will increase an average of 11.6 percent per year through 2008, reaching a total of 83 million pounds, compared to 48 million in 2003. 350 8.19.2.2 Other Polysaccharides. Some biodegradable or biobased plastics are made by starting with cellulose and modifying it to make it thermoplastic. For example, the Japa- nese company Ebara Jitsugyo, Ltd. (EJ CO), manufactures several products based on cellulose acetate that are claimed to be biodegradable. 366 Some efforts are being made to develop biodegradable plastics based on chitosan, produced from shrimp and crab shells. One company involved in this effort was Aisero Chem- Starch-based (continued) Greenpol Greensack Mater-Bi Paragon Placorn Plantic Renature Solanyl Star-Kore Supol SWIRL Vegmat Greenpol Co Convex Plastics Novamont Avebe Bioplastics Nihon Shokuhin-Kako Plantic Technologies Marfred Industries, Storopack Rodenburg Biopolymers Star-Kore Industries Supol GmbH Milleta Vegeplast * Note: not all of these plastics are currently commercially available; reported compositions in some cases may be in- accurate. TABLE 8.7 Reported Composition of Selected Biodegradable Plastics *355–358 (Continued) Polymer category Trade name Manufacturer Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS 8.93 ical, in Japan. Other natural polysaccharides have also been investigated. Hayashibara produced Pullulan polysaccharide-based films, with properties similar to polystyrene. Pul- lulan is still used in cosmetics applications but does not appear to be used as film. 8.19.2.3 PHB, PHBV, and Other Bacterial Polyesters. Currently, the leading company in the development of polyhydroxyalkanoates (PHAs), a type of polyester produced by bi- ological fermentation, is Metabolix, based in Cambridge, MA. The company’s PHAs are stable to water but biodegrade in fresh water, sea water, soil, and composting environ- ments. They also degrade under anaerobic conditions such as in septic systems and municipal waste treatment plants. The polymers are also claimed to be recyclable. Properties of homopolymers and copolymers in this family vary from strong moldable thermoplastics to highly elastic to soft and sticky, depending on the chemical composition. Molecular weights range from about 1 thousand to 1 million. The polymers are produced in “biofac- tories” by accumulation inside microorganisms (produced by recombinant DNA) and later harvesting. The company has demonstrated its fermentation technology, based on renewable resources such as corn sugar and vegetable oil, on the tonnage scale and claims that commercial-scale trials indicate that production costs will be well under $1 per pound. This is much lower than was achieved by previous ventures into PHA production. Metab- olix is also engaged in research to produce PHAs directly in nonfood crop plants. The U.S. Department of Energy has supported research on using native American prairie grass for this purpose, through genetic engineering. In 2005, Metabolix was awarded the 2005 Pres- idential Green Chemistry Award in the small business category for its progress in commer- cializing these materials. 367,368 In 2004, Metabolix announced an alliance with Archer Daniels Midland to commer- cialize its fermentation technology. The two companies, in a 50/50 joint venture, will es- tablish a state-of-the-art 50,000 ton production facility and will manufacture and market natural PHA polymers for a wide variety of applications, including coated paper, film, and molded products. 369 Also in 2004, Metabolix began a joint project with the U.S. Army Natick Soldier Center on development of PHA packaging film for the Navy. The project is being supported by the Navy’s Waste Removal Afloat Protects the Sea (WRAPS) Program. It focuses on melt-processing PHA films used to enclose many of the fresh foods found in grocery stores and may also include exploration of nanocomposites and coextruded multi- laminate systems as potential food packaging systems for both the Navy and the Army. 370 In 2005, Metabolix announced an alliance with British Petroleum to further develop direct production of its PHAs in switchgrass. The two-year agreement will research and develop grass crops containing high levels of naturally grown polymers that can be used to produce biodegradable plastics. A coproduct will be “advantaged biomass material which can be converted to energy.” 371 Recently, investigators at University College in Dublin, Ireland, found that a certain strain of bacteria can use waste styrene to make PHAs, opening the door for remediation of a toxic waste and its conversion into a useful plastic at the same time. The team is working on scale-up and increasing the efficiency of the bacterial action to make commercially useful amounts of PHA plastics. 372 8.19.2.4 Polylactides. Polymers based on lactic acid have a very long history. DuPont patented the ring-opening polymerization process for lactic acid polymers, following conversion of lactic acid to a cyclic dimer in the first reaction stage, back in 1954. 373 Appli- cations were primarily in the medical area, including items such as absorbable sutures. High cost was a major deterrent to more widespread use. One of the key developments permitting more economical production of polylactides, and opening the door to larger- volume uses such as packaging, was development of the ability to control the ratio and distribution of the d- and l- forms of lactide in the polymer backbone. This is essential to Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS 8.94 CHAPTER 8 controlling crystallization and producing plastics with the desired combination of physi- cal properties. The development of polylactides for packaging and other nonmedical applications was spurred by a partnership between Dow Chemical Company and Cargill. Cargill had begun working on polylactides before 1987. They began production of pilot plant quantities in 1992, under the EcoPLA name, and built a 4000-tonne-per-year facility near Minneapolis. The 1997 joint venture with Dow, under the name Cargill Dow Polymers, enabled further commercialization of these materials. 374,375 In 2005, Cargill bought Dow out of the company, which is now operated as a wholly owned subsidiary of Cargill under the name Na- tureWorks LLC. In addition to NatureWorks PLA plastics, the new company sells PLA fiber under the Ingeo brand name. Cargill reports that PLA prices are now competitive with PET. 376 The current production method for polylactide plastics begins with bacterial fermentation of carbohydrates, generally cornstarch that has first been fermented to sugar using a type of lactobacillus. In 1992, Cargill patented a polymerization process for polylactide production using prepolymerization to low-molecular-weight polylactic acid, catalytic conversion to lactide, and finally ring-opening polymerization to produce PLA. The properties of the resulting polymer are determined by its molecular weight and the proportion of d-, l-, and meso-lactide in the polymer and by processing conditions. 377 Cargill Dow built a large commercial facility for PLA production near Blair, NE, which opened in 2002. PLA bottles are currently being used for Biota water bottles. Since the molding temperature for these bottles is lower than for PET, energy savings are claimed. The bottles are claimed to be the first in the world to be approved by the Biodegradable Products Insti- tute. The bottles are substantially heavier than the PET alternative, but reportedly this was done by choice so that the bottle would have a premium feel. The bottles will disintegrate in 75 to 80 days in a composting environment that provides a temperature of 120 to 140 o F, microorganisms, and moisture. They will not, however, degrade quickly in a backyard compost operation, as these do not reach as high a temperature. 378 Alcas, of Italy, is using NatureWorks PLA for its ice cream cups and tubs as well as for drinking glasses, straws, and spoons in its “02 line.” The name stands for “zero consumption × zero waste.” 379 Sony reports it is using PLA with other materials, including an inor- ganic flame retardant, in casings for some of its electronics products. 380 In 2005, Fujitsu claimed to be the first company to use PLA in a large laptop computer; the material used is a blend of about 50 percent PLA with an amorphous plastic developed by Toray. 381 In 2004, the Belgian brewery Alken Maes became the first Belgian brewer to use PLA cups. Previously, the brewery used polycarbonate cups at public festivals but saw the PLA cups, made by Huhtamaki from Cargill Dow’s NatureWorks PLA, as a more environmentally friendly option. 382 In 2005, Sharp Corporation announced that it has developed technology to blend PLA with polypropylene recovered from electronics recycling, using a newly developed com- patibilizer that greatly improves the properties of the blended materials. Its intent is to use the blend in new consumer electronics, thus significantly reducing their environmental impact as compared to using petroleum-based feedstocks. 383 NAT-UR, in 2005, became the first cutlery product to be granted the Biodegradable Products Institute compostable designation. The utensils are manufactured with NatureWorks PLA in combination with starch. They are reported to degrade in 30 to 60 days in a compost environment. 69 Several companies have determined that IR sorting equipment will successfully sepa- rate PLA from a PET recycling stream. 384 Freedonia predicts demand for PLA will grow at an annual rate of 24.6 percent through 2008, reaching a total of 135 million pounds that year, compared to 45 million in 2003. 350 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS 8.95 8.19.3 Other Biodegradable Polyesters 8.19.3.1 Polycaprolactone. Polycaprolactone has been used in relatively small quantities for a long time. The most well known supplier was Union Carbide, which manufactured Tone brand polymers, which are compostable. Dow Chemical acquired this technology when it acquired Union Carbide and continues to manufacture Tone polymers. 385 8.19.3.2 Ecoflex. BASF manufactures Ecoflex, a synthetic aliphatic-aromatic copolyes- ter. Ecoflex resins have been certified as compostable by the Biodegradable Products Insti- tute, DIN CERTCO in Europe, and the Biodegradable Plastics Society in Japan (which describes the polymer as polybutylene adipate/terephthalate). When used for bags for collecting and composting food scraps and yard trimmings, disposable packaging or agricultural sheeting, it decomposes in compost within a few weeks without leaving any residues. Combinations of thermoplastic starch and Ecoflex are used for films and coatings for food packaging. BASF’s plant in Ludwigshafen, Germany, has a production capacity of 8000 tonnes per year. 386 In 2005, the company announced that it will start up a new 6000- tonne-per-year plant in early 2006, at Schwarzheide in Germany, due to the expanding world market for biodegradable plastics. In particular, the company mentioned the amend- ment to the German packaging ordinance that exempts packaging certified as biodegradable from fees under the German DSD packaging ordinance until 2012. Ecoflex F is designed for flexible film applications, whereas Ecoflex S is designed for blends. Most current use of Ecoflex is in blends with other renewable materials, including starch, cellulose, and polylactic acid. 387,388 8.19.3.3 Eastar Bio. Eastar Bio is a family of copolyesters developed by Eastman Chemical Company in 1998. Properties are similar to low-density polyethylene. The material meets requirements for food contact in a variety of applications and is compostable. In September, 2004, Eastman sold the business and technology to Novamont. 389 8.19.3.4 Polybutylene Succinate (PBS). Manufacturers of polybutylene succinate, produced from polymerization of succinic acid and 1,4-butanediol, include Showa Highpoly- mer, which produces Bionolle polymers; SK Polymers, which makes SkyGreen BDP; and Mitsubishi Chemical. Normally, the source of both monomers is maleic anhydride. How- ever, Mitsubishi is working with Ajinomoto to produce succinic acid by fermentation of sugar and starch, providing a biodegradable polymer that is partly biobased. 390 8.19.3.5 Biomax. Biomax is a family of aliphatic/aromatic polyesters based on polyethylene terephthalate and manufactured by DuPont. A combination of hydrolysis and microbial action breaks down the polymer, and some grades have been certified as compostable. Reportedly, as many as three different proprietary aliphatic monomers may be incorpo- rated into the polymer. 391 8.19.3.6 Polyvinyl Alcohol and Other Water-Soluble Plastics. Several water-soluble polymers have a long history of use in niche applications. Many of these polymers are bi- ologically stable when they are in the solid state but will biodegrade readily once they are dissolved. These include polyvinyl alcohol, cellulose esters and ethers, acrylic acid polymers, polyacrylamides, and polyethylene glycol, among others. Polyethylene oxide is biodegradable at low molecular weights. 8.19.3.7 Polyvinyl Alcohol. Polyvinyl alcohol is formed by hydrolysis of polyvinyl acetate. By controlling the degree of hydrolysis, the solubility can be modified, resulting in Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS 8.96 CHAPTER 8 grades that will dissolve only in hot water or grades that dissolve in cold water as well. Some grades can be extruded, but others must be cast from solution. One important application is in laundry bags and hamper liners for use in health care facilities. The filled bag is sealed shut with an attached adhesive strip. When placed in the washer, the adhesive and bag break down completely during the hot washing and disinfec- tion. Any remaining polymer will biodegrade during the wastewater treatment process. The bags are impermeable to bacteria and viruses during normal use, as well as resistant to gases, solvents, and cool liquids, so they cut the risk of contamination, protecting hospital staff. 354 PVOH films are also used to encapsulate agricultural chemicals to avoid human exposure when the chemicals are measured into water for application to crops. It is widely used as a binder and has other niche applications as well. One of the first manufacturers of polyvinyl alcohol (PVOH) was Air Products & Chemicals, which manufactured it under the Airvol trade name. It appears that the product may no longer be available, however. Another early manufacturer was ChrisCraft Indus- trial products, Inc., which still makes PVOH through its Monosol division. Another major supplier is Kuraray, which makes a variety of water soluble plastics, including PVOH under the name Poval. DuPont sells PVOH under the Elvanol tradename and Polyval under the name Enpol. There are other suppliers as well. 8.19.4 Other Biodegradable Plastics A number of investigators are working on the development of protein-based plastics. In some cases, these are being targeted as edible films. Of course, if a film is edible, it is generally biodegradable. Starting materials include zein, a corn protein; soy protein; and other materials. None of these materials has yet reached any large-scale commercial application. Researchers at Cornell have created a biodegradable polymer called polylimonene carbonate, from limonene obtained from orange peel and converted to limonene oxide, plus carbon dioxide. The polymer has properties similar to those of polystyrene and has potential to use carbon dioxide that would otherwise be emitted into the atmosphere, adding to the greenhouse effect. 392 8.19.5 Nonbiodegradable Biobased Polymers As mentioned, there has also been interest in biobased polymers because of their basis on renewable feedstocks, regardless of whether they are biodegradable. One of these materials is Sorona™, manufactured by DuPont. In 2004, DuPont and Tate & Lyle PLC, a Lon- don-based renewable ingredients company, formed a joint venture, DuPont Tate & Lyle BioProducts LLC. A plant in Louden, TN, will produce the key polymer building block, 1,3-propanediol (PDO), by fermentation from corn sugar in place of the petroleum-based process currently used. The polymer will then be 37 percent based on corn. DuPont has a goal of deriving 25 percent of its revenue from nondepletable resources by 2010, and this will be a step toward that goal. In 2002, the company derived 14 percent of its revenue from such resources. Sorona is intended for a variety of applications, including textile ap- parel, interiors, engineering resins, and packaging. Sorona is not biodegradable, although DuPont says it has the technology to make biodegradable Sorona resins if the market grows for such materials, and mentions packaging as a potential application. 393,394 Another market for biopolymers is production of polyurethanes. Soybean oil can be combined with an isocyanate to create soy polyol, which can then be used in all types of rigid and flexible polyurethane foam applications. 395 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS [...]... 2004, p 4 7 Powell, J., The Squeeze is on in Plastics Recycling, Resource Recycling, Nov 2003, pp 19–22 8 China Spells Crisis for Postconsumer Plastics, C&EN, May 17, 2004, p 11 9 Toloken, S., NAPCOR Laying Off President, Two Execs, Plastics News, May 24, 2004, p 1, 27 10 Association of Plastics Manufacturers in Europe, Plastics in Europe; An Analysis of Plastics Consumption and Recovery in Europe,... Plants Will Recycle Painted TPO Parts,” Plastics News, Nov 15, 1999, p 12 293 Polymer Sciences, Inc., http://www.polymersciences.com/ 294 Milan Injection Moulding Plant—USA, Plastics Technology, 295 Brooke, L., Plastics Recycling Goes Global, Automotive Industries, Feb., 2000 296 ACI Plastics, http://www.aciplastics.com/ 297 Miel, R., ACI ‘Liberates’ Instrument-panel Plastics, Plastics News, April 24, 2000,... use is subject to the Terms of Use as given at the website PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website Source: Handbook of Plastics Technologies CHAPTER 9 PLASTICS AND ELASTOMERS:... California Dept of Conservation, www.consrv.ca.gov 21 California Department of Conservation, Calendar Year 2004 & Biannual Report of Beverage Container Sales, Returns, Redemption & Recycling Rates, May 10, 2005 22 California Department of Conservation, Californians Set State’s All-Time Record for Bottle and Can Recycling in 2004, press release, May 19, 2005 23 California Department of Conservation,... http://www.petbottle-rec.gr.jp/english/en_design.html 304 Association of Plastics Manufacturers in Europe (APME), Design for Recycling of Rigid Plastics Containers, Brussels, June, 1996 305 Petcore, Guidelines on Acceptability of Additives and Barrier Materials in the PET Waste Stream for an Effective Recycling of PET, http://www.petcore.org/chargement/publications/ Guidelines.pdf 306 Europa, Management of End of Life Vehicles, http://europa.eu.int/scadplus/leg/en/lvb/... Organization, ISO 11469:2000: Plastics Generic Identification and Marking of Plastics Products, May 2000 62 Commission Decision of 27 Feb 2003 Establishing Component and Material Coding Standards for Vehicles Pursuant to Directive 2000/53/EC of the European Parliament and of the Council on End -of- Life Vehicles, Of cial Journal of the European Union, L 53/58, Feb 28, 2003, http://europa.eu.int/eur-lex/pri/en/oj/dat/2003/l_053/l_05320030228en00580059.pdf... the maleic anhydride graft level of the impact modifier Rubber particle size averages of greater than 0.25 µm and less than 0.5 µm are required to achieve the required balance of mechanical performance Optimum particle size varies with the percentage of rubber Nylon 6,6 is often blended with PPO (Noryl GTX) to make extremely rigid polymers for exterior body panels Most of its applications are in Europe,... Urges Against the Use of Opaque White PET, Plastics News, April 29, 2002, p 13 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2006 The McGraw-Hill Companies All rights reserved Any use is subject to the Terms of Use as given at the website PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS 8.107 303 The... to the Terms of Use as given at the website PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS 8.100 CHAPTER 8 56 Society of the Plastics Industry, SPI Resin Identification Code: Guide to Correct Use, http:// www.plasticsindustry.org/outreach/recycling/2124.htm 57 Environmental Packaging: U.S Guide to Green Labeling, Packaging and Recycling, Thompson Publishing Group, Tampa, FL, 2000 58 PACIA, Plastics Coding... use is subject to the Terms of Use as given at the website PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS 8.109 370 Miller, M., Metabolix Wins Grant to Explore PHA Bioplastics for Packaging Film, Metabolix press release, March 2, 2004 371 Barber, J and O Peoples, BP and Metabolix Agree to a Joint Development Program for Renewable Plastics, Metabolix press . as products with recycled content are given preference. Plastics may undergo a variety of other types of degradation. Of particular interest in the context of this discussion are photodegradation and hydrolytic. problem, the use of biodegradable plastics can greatly reduce their prevalence and longevity in the environment. This can be of particular value for plastics that may reach water systems. Plastics in. Terms of Use as given at the website. PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS PLASTICS RECYCLING AND BIODEGRADABLE PLASTICS 8.89 One concern that is frequently raised about degradable plastics

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