Are Biodegradable Plastics the Future of Plastics?

Plastics are versatile materials. They are used to manufacture many useful products like bags, buckets, cups, mugs, food wraps, product packaging etc. Plastics are long carbon chain polymers and are mostly produced from petrochemicals. In spite of their benefits, they have been bad for the environment. Hardly few of them are recycled and most of them end up in landfills. They are not biodegradable and cannot be composted. If they are carelessly disposed off in water bodies, they can cause damage to aquatic life as fishes and whales may accidentally consume them. Even burning of plastics is not a good solution as they emit toxic chemicals such as dioxins. Because of environmental concerns of using conventional plastics, the biodegradable plastics are gaining focus around the world.

 Biodegradable plastics are those plastics that can be degraded by the action of micro-organisms. All biodegradable plastics cannot be composted. Those that can be composted are known as compostable plastics. Different biodegradable plastics degrade under different specified and tested conditions. Compostable plastics need to adhere to a set of requirements such as fragmentation, absence of ecotoxicity, and treshold concentration of pollutants such as heavy metals. The compostable plastics need to meet specific standards of compostability. These standards are:-
  1. ASTM D6400, which is an American standard for solid material biodegradation required for labelling plastics designed to be aerobically composed in municipal or industrial facilities.
  2. EU 13432 is a European standard.
There are two types of biodegradable plastics depending on source. The first one is bioplastics which are produced from plant sources like corn starch and biomass and the other one is petrochemical based biodegradable plastics. The examples of bioplastics are Polyhydroxyalkanoate (PHA), Polylactide Acid (PLA), Cellulose Acetate and starch based. The examples of petrochemical based biodegradable plastics are Polybutylene succinate (PBS), Polycaprolactone (PCL), Polybutyrate adipate terephthalate (PBAT) and Polyvinyl alcohol (PVOH/PVA).
Figure 1 : Biodegradable Plastics


Advantages And Disadvantages
The advantages of using biodegradable plastics are:-
  1. Biodegradable plastics can reduce greenhouse gas emission.
  2. Biodegradable plastics can be degraded naturally by the action of microbes.
  3. Biodegradable plastics consume less energy during the manufacturing process.
  4. Biodegradable plastics reduces the amount of wastes.
  5. Biodegradable plastics may reduce the dependence of fossil fuels for the production of plastics.
The disadvantages of biodegradable plastics are:-
  1. Some biodegradable plastics decompose in landfills to produce methane gas which is a greenhouse gas.
  2. Biodegradable plastics do not always readily decompose. They may take many years to break down.
  3. They may leave behind toxic residues such as heavy metals and may contain herbicides and pesticides.
  4. Some bioplastics are produced from maize or corn starch. Corn is also a food crop. Instead of food, it is grown to produce bioplastics which may affect the food security of the nation.
  5. Biodegradable plastics may not solve ocean pollution problem.
References

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