Biodegradable polymers

Abstract

Degradable Materials Biodegradable polymers are important to minimize solid municipal waste accumulation, and as a way to achieve safe, environmentally friendly products. The purpose of this paper is to focus on the biodegradable aspects of polymer performance, however it is recognized that several types of degradability can occur. This includes photodegradation and photo-oxidation with light-induced initiation, physical degradation by mechanical initiation, chemical degradation by chemical initiation and bioerosion and biodegradation by biological forces. Several considerations can by employed to determine what would make a degradable material such as: degradability by naturally occurring enzymes such as starch and polyvinyl alcohol, cleavable linkages like aliphatic polyesters, oxidative instability of polymers like polyisoprene and polybutadiene, hydrophilic materials such as polyethylene glycol, and low molecular weight materials that are assimilated by microbes. The majority of the common synthetic polymers in routine commercial use are not biodegradable. Those materials that are biodegradable contain polar groups and decompose at typical processing temperatures. This prevents their use in polymer and plastic processes such as injection molding, thermoforming, extrusion, film casting, and fiber preparation. Attempts to develop new biodegradable polymers can be considered to be centered around: modification of natural polymers, modification of synthetic polymers, biodegradable composites, and preparation of polymers with biodegradable backbones. Some of these approaches have led to useful commercial products, and the utility of each of the approaches will be considered.