Environmental degradation of plastic

The standard ASTM D6954-04 is used for the exposure of plastics that can degrade by a combination of oxidation and biodegradation (87). This standard should permit the comparison and ranking of the overall rate of the environmental degradation of plastics in the course of thermal or photo oxidation. Each degradation stage is independently evaluated to allow a combined evaluation of a polymer s environmental performance. 

The environmental accumulation of plastic waste in the last decades is simply due to the fact that the plastic commodities, as obtainable from the unsubstitutable polymeric materials based on the fossil fuel feedstock. These are consisting of full-carbon backbone macromolecules, which are characterized by degradation... 

Abiotic hydrolysis is the most important reaction for initiating the environmental degradation of synthetic polymers (Gbpferich 1997) such as PE (Gu 2(X)3), PTT (Heidary and Gordon 1994), PLA, and their copolymers (Hiltunen et al. 1997 Nakayama et al. 1996). The degradation of most synthetic plastics in nature is slower than that of natural polyesters. This process involves environmental factors, followed by the action of microorganisms in their surroundings (Albertsson et al. 1994 Cruz-Pinto et al. 1994). 

M. B. Neiman, Aging and Stabilization of Polymers, Consultants Bureau, New York, 1965. S. H. Pinner, Weathering and Degradation of Plastics, Columbine Press, Manchester, 1966. J. Voigt, Die Stabilisierung der Kunststoffe gegen Ucht und Wdrme, Springer, Berlin, 1967. D. V. Rosato and R. T. Schwartz, Environmental Effects on Polymeric Materials, Interscience, New York, 1968. 

Verification of the degradation of plastics in aqueous systems is a part of the worldwide effort to develop environmentally responsible packaging and delivery material. One of the major issues raised in connection with degradable plastics is the fate and toxicity of degraded products. 

Approaches to reduce evaporation and degradation of plasticizers have been developed, with the aim of formulating long-lasting flexible plastics and minimizing the ultimate environmental impact of these chemicals. Also, fire-retardant plasticizers and plasticizers for use in biodegradable plastics have been developed (2). 

To be considered as environmentally degradable, a plastic must satisfy at least two requirements. On outdoor exposure or soil burial it must become brittle rapidly enough to disappear visually, and the degraded material must be susceptible to biological attack giving complete conversion to biomass without release of toxic products. 

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