Plastics environmental degradation

Plastics, Environmentally Degradable" in ECT 3rd ed., SuppL VoL, pp. 626—668, byj. E. Potts, Union Carbide Corp. 

Potts, J. E. 1984. Plastics, environmentally degradable. In Kirk-Othmer Encyclopedia of ChemicalTechnology, M. Grayson, ed., pp. 1022-79. Wiley-Interscience, New YorL... 

Potts, James E. (1983) Plastics, environmentally degradable, in The Encyclopedia of Chemical Technology, John Wiley and Sons. 

Potts, J.E., 1984, Plastics, Environmentally Degradable. In Kirk-Othmer Encyclopedia of Chemical Technology, 3rd ed., John Wiley Sons, NY, Suppl., pp. 626-668. 

There are signs that the use of environmentally degradable polymers and plastics is expanding. As the market begias to become aware of the availabihty of these new materials, it is expected that they will move iato niche opportunities. When this occurs, production will iacrease, and costs, the biggest barrier to acceptance, should begia to come down. Some of the polymers ia production at some scale larger than laboratory are shown ia Table 5. 

ASTM Standards on Environmentally Degradable Plastics, ASTM Pubhcation Code Number (PCN) 03-420093-19, American Society for Testing and Materials, Philadelphia, Pa., 1993. 

Low temperature can lead to embrittlement of plastics. This is not seen as a time-dependent effect, but it can be the cause of rapid failure should environmental degradation be followed by a fall in temperature. 

This overview is an attempt to briefly cover the history and recent developments In environmentally degradable commodity and specialty polymers and plastics. Degradation pathways are mentioned, polymer types, including blends, are reported and the limitations of current testing protocols raised. The chapter concludes with generalizations on structural requirements for degradable polymers. 

Narayan R, ASTM International Subcommittee D20.96 (2008) Biobased content briefing paper ASTM subcommittee D20.96 on environmentally degradable plastics and biobased... 

Finally, the use of low-molecular-weight species to improve flow properties called plasticizers normally reduces stiffness, hardness, and brittleness. Plasticization is usually restricted to amorphous polymers or polymers with a low degree of crystallinity because of the limited compatibility of plasticizers with highly crystalline polymers. Other additives, such as antioxidants, do not affect the mechanical properties significantly by themselves, but can substantially improve property retention over long periods of time, particularly where the polymer is subject to environmental degradation. 

The polychlorinated biphenyls (PCBs, coplanar biphenyls) have been used in a large variety of applications as dielectric and heat transfer fluids, lubricating oils, plasticizers, wax extenders, and flame retardants. Their industrial use and manufacture in the USA were terminated by 1977. Unfortunately, PCBs persist in the environment. The products used commercially were actually mixtures of PCB isomers and homologs containing 12-68% chlorine. These chemicals are highly stable and highly lipophilic, poorly metabolized, and very resistant to environmental degradation they bioaccumulate in food chains. Food is the major source of PCB residues in humans. 

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