|University Federico II
of Naples, Italy
Plastics that are destroyed directly from the environment in reasonable times are called "biodegradable".
In the long period, nearly all substances are transformed by natural agents. The important distinction is time and way of degradation of a given material. An oil derived plastics takes 100 to 1000 years to degrade, a banana skin takes just a few months.
Escherichia coli, a common bacterium
Biodegradable plastics are susceptible to be attacked by microorganisms, such as fungi and bacteria, that are normally present in soil, air and water, until they are completely metabolized. This process is biologically clean, the products of the degradation are those of the normal biological activity, namely carbon dioxide and water.
Many polymeric systems can be envisaged for a "biodegradable" approach to pollution issues. Some are commercially available, others are being developed. Some are synthetic, like aliphatic polyesters, polycarbonates, polyols, and their mixtures; biodegradable block copolymers and polymer composites. Others are natural, sometimes modified to enhanche biodegradation, and are called bioplastics: polyesters and, above all, vegetable and animal polysaccharides.