Biopolymers - A Biodegradable Alternative to Plastic Bags and Bottles

The Problem: Excessive Plastic Products in Landfills
People have become accustomed to buying their food in clean, nicely designed packaging, using detergents bottled in handy plastic containers or personal hygiene products which are not disposable. All these improvements are here to stay because they are convenient but there is another, less desirable, side to this coin in that they are adding enormous volumes to household wastes because they are of the ’single-use’ type and must thus be disposed of after being used for a relatively short time.

The problem is not the convenience of the product but the sheer impossibility to discard it in a way that does not add to the glut of landfills or does not contribute to air and water pollution or provokes untimely, detrimental changes. Conventional, oil-based plastic materials, because of their inherent durability, are among the main culprits of today’s environmental problems. If no action is taken, they will also contribute, even more significantly, to tomorrow’s ones.

The answer SEEMS remarkably simple
Make plastics which have a shorter life without compromising their most desirable and useful properties. However, the way to achieve this is not as easy as it may seem. During the last decade, and even before, considerable R&D efforts have been directed at coming up with a viable alternative to conventional plastics.

Poly(lactic acid), PLA, possibly with a few other biopolymers, is among the most promising of these new materials because it is entirely biodegradable, for instance by composting, returning its natural building blocks to nature’s life-cycle, and providing properties which are equivalent or better than those of today’s plastic materials.

The Controversy
The controversy within the industry as to which materials should be considered biodegradable continues unabated. Several of the materials in question include polyolefin-based compositions and polymers containing aromatic groups. Microorganisms have difficulty using these materials in their metabolism.
Part of the current debate is defining an acceptable period of time for the biodegradation to be completed. Almost all carbon-based materials biodegrade given an acceptable period of time.

This includes polymers that producers market as fully biodegradable. Most producers define a fully biodegradable polymer as a polymer that is completely converted by microorganisms to carbon dioxide, water and humus. In the case of anaerobic biodegradation, carbon dioxide, methane, and humus are the degradation products.

References:
Biodegradable Polymers SRI Consulting

Biodegradable Polymer Research Center (BPRC) University of Massachusetts Lowell