Environmental issues biodegradable polymers

Rayon is unique among the mass produced man-made fibers because it is the only one to use a natural polymer (cellulose) directly. Polyesters, nylons, polyolefins, and acryflcs all come indirectly from vegetation they come from the polymerization of monomers obtained from reserves of fossil fuels, which in turn were formed by the incomplete biodegradation of vegetation that grew millions of years ago. The extraction of these nonrenewable reserves and the resulting return to the atmosphere of the carbon dioxide from which they were made is one of the most important environmental issues of current times. CeUulosic fibers therefore have much to recommend them provided that the processes used to make them have minimal environmental impact. 

Polylactates are an interesting class of biodegradable polymers which may be made from either renewable or petroleum feedstocks. The synthesis of lactic acid raises real issues concerning the relative greenness of the renewable and non-renewable (HCN) route as discussed in Chapter 2. A summary comparison of the greenness of both routes is shown is Table 6.4. Without a full LCA the choice of route on environmental grounds is not easy and at least partly depends on plant location and raw material availability. 

The book reviews the properties and industrial applications of polymers and discusses their environmentai benefits compared with traditional materials. It also addresses the issues of polymer durability, recycling processes to aid waste minimization and biodegradable polymers. This text is intended to introduce the non-specialist reader to the benefits and limitations of polymeric materials from an environmental viewpoint, and will prove a useful book for both students and professionals. 

The concern over environmental issues and sustainability has opened up another vibrant research field, namely, biobased and biodegradable polymer blends. An overview of major developments and recent trends in biodegradable blends with an emphasis on PLA blends are also discussed. This chapter closes with an outlook for the future of this important subject. 

PHB has many physical properties in common with poly(propylene), and a PHB-PHV copolymer (BIOPOL) has recently been used to manufacture plastic shampoo bottles. PHB-PHV is of special interest because it is biodegradable. Since it is a naturally occurring polymer, it is easily degraded by enzymes produced by soil microorganisms and therefore does not persist in the environment after disposal. Other biodegradable polymers, such as polyesters derived from e-caprolactone and lactic acid, are also known and have been commercialized. Although it remains to be seen how widespread the use of biodegradable plastics will become, research and development of these materials is sure to continue as we try to deal with contemporary environmental issues. ... 

For biodegradable polymers (industrial), composting was the first environmental process for which specifications were developed. In the nineties, two parallel developments took place in Europe, resulting in the publication of DIN V 54900 in 1998 and EN 13432 in 2000. In spite of some minor differences, both norms were largely similar. After a few years, the DIN norm was made redundant as several international norms (EN and ISO) dealt with the same issue. In addition, in North America a norm was published in 1999 on specifications for (industrial) compostability ASTM D6400. On a global level, ISO 17088 in the field of plastics was published in 2008, while a similar norm for packaging is close to publication and now available under the form of a Draft International Standard (DIS), ISO DIS 18606. 

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