Polyolefins environmentally degradable

Degradation of polyolefins such as polyethylene, polypropylene, polybutylene, and polybutadiene promoted by metals and other oxidants occurs via an oxidation and a photo-oxidative mechanism, the two being difficult to separate in environmental degradation. The general mechanism common to all these reactions is that shown in equation 9. The reactant radical may be produced by any suitable mechanism from the interaction of air or oxygen with polyolefins (42) to form peroxides, which are subsequentiy decomposed by ultraviolet radiation. These reaction intermediates abstract more hydrogen atoms from the polymer backbone, which is ultimately converted into a polymer with ketone functionahties and degraded by the Norrish mechanisms (eq. 

These environmentally degradable polyolefins, because of their cost/ performance profiles are very competitive for the growing markets for such plastics. They will be strong competition for the polyester types such as poly(lactic acid) and polyhydroxyalkanoates so frequently publicized as the innovative solution to plastic waste management. 

The history of the development of environmentally degradable polyolefins reveals some interesting technologies and innovation. Unfortunately most were without much commercial success. A few of these are shown below ... 

Collectively, these technical approaches indicate the potential of polyolefins to environmentally degrade and subsequently biodegrade individually they do not always have enough substantiated evidence and data to be unequivocal. It is the approach using transition metals as oxidation catalysts that has become the predominant technology in the environmental degradation of polyolefins. The... 

Are a commercially viable approach to developing environmentally degradable polyolefins. 

Promote polyolefins as complementary to and competitive with current plastics which are available for the environmental degradation market. 

D.M. Wiles, S. Gerald, Polyolefins with controlled environmental degradability. Polym. Degrad. Stab. 91, 1581-1592 (2006)... 

Interest in environmentally degradable polymers began more than thirty years ago, when it was first recognized that the commonly used commodity packaging plastics such as polyolefins, poly(vinyl chloride, polystyrene, and poly(ethylene terephthalate) were accumulating in the environments in which they were discarded, after use. Since these polymers were developed for their resistance properties, it should not have been surprising that they were recalcitrant in landfills and as litter when disposed of in a negligent manner. 

ENVIRONMENTALLY DEGRADABLE PLASTICS BASED ON OXO-BIODEGRADATION OF CONVENTIONAL POLYOLEFINS.313... 

Environmentally Degradable Plastics Based on Oxo-Biodegradation of Conventional Polyolefins... 

During a study of the environmental degradation of polyolefins, Scott et al. found that the outdoor stability of the polyolefins could be very markedly reduced by accelerated peroxidation in the presence of transition metal ions (Fig. 12.2). Metal ion catalysed peroxidation occurs uncontrollably during processing and on exposure to the environment and consequently it is of little practical value unless the formation of hydroperoxides is controlled by appropriate antioxidants. ... 

BiUingham N C, Bonora M and De Corte D, Environmentally degradable plastics based on oxo-biodegradation of conventional polyolefins in Proceedings of the 7th World Conference on Biodegradable Polymers and Plastics, Pisa, June 4—8, 2002. 

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