DEGRADABLE PLASTICS
One type of plastic that has gained exposure over the past several years is degradable plastics. Degradable plastic is designed to undergo a significant change in its chemical structure under specific environmental conditions resulting in a loss of some properties that may vary as measured by standard test methods appropriate to the plastic and the application in a period of time that determines its classification (ASTM D 883). In order to understand degradable materials, one must note the differences in classes of degradable plastics such as:
- Biodegradable Plastic – a degradable plastic in which the degradation results from the action of naturally-occurring micro-organisms such as bacteria, fungi and algae. (ASTM D 883)
- Compostable Plastic – a plastic that undergoes biological degradation during composting to yield carbon dioxide, water, inorganic compounds, and biomass at a rate consistent with other known compostable materials and leaves no visually distinguishable or toxic residues. (ASTM D 883)
- Photodegradable Plastic – a degradable plastic in which the degradation results from the action of natural daylight. (ASTM D 883)
Applications
Degradable plastics have been developed for a range of applications. Biodegradable plastics have been used in commercial applications including bottles, food packaging, bags and utensils. They are used in applications such as non-woven fabrics, film, fiber, adhesives and coatings. Certified compostable plastic bags are being used in the collection of food and yard waste destined for municipal composting operations. Photodegradable plastic has been used to make six-pack ring for beverage cans or bottles that quickly loses its strength under the action of ultraviolet light therefore reducing the likelihood of trapping wildlife.
Research
Research on degradable plastics ranges from the development of new degradable plastics to new uses for existing materials. Focus also includes cultivation of renewable raw materials, degradable plastics processing, disposal and recovery. Research is ongoing by the United States government, individual companies, academia and other organizations around the globe.