Properties and Biodegradation Nature of Thermoplastic Starch

Abstract

For the last few decades, the usage of plastic increased because of its specific properties such as low cost, light weight, high strength, non-biodegradability, durability, non corrosive nature, process ability and high energy effectiveness. Hence these plastics can be used for various application which includes household articles to aeronautic sector. Now a day it’s difficult to imagine a life without plastic which are mostly derived from crude oils and natural gas. Among the various polymers, polyethylene, polypropylene and polystyrene are used greatly for food packaging, biomedical field and in agriculture. According to statistics, from 1950 onwards, 9% of growth can be seen globally, in the production and consumption of plastics. In 1950 the overall production of plastic was 1.5 million tones while it reached 245 million tones in 2008. In these polyethylene is one of the most dominant packaging material, creating the real problems in the disposal of one-trip packaging. These polymers will take millions of years to degrade under natural weathering conditions. Hence careless dumping of these plastics after its usage creates severe problems to the environment. Also during combustion it produces toxic materials which eventually pollute the atmosphere. The land filling results in the contamination of water, thereby adversely affecting the soil’s biological balance. ‘Recycling’ is another solution for reducing the amount of waste polyolefin materials. But recycling has its own limitation in regard to compatibility of different polyolefins which adversely affects the processability and final properties. Subsequently the problems created by plastic wastages to the environment triggered the interest in the development of biodegradable disposable plastics. So that the onetime use items can be disposed off with the hope that they will not remain for centuries in a landfill, or as litter, which is one of the tenets driving the recent interest in “green” technologies. The current biodegradable plastics, such as PLA, PHBV, Mater-Bi etc are very costly and the processing and mechanical properties of these materials are not good enough for the production of consumer products. Hence several studies were conducted to modify the current commodity plastics such as polyethylene, polypropylene into biodegradable type. One method to achieve this goal was blending of plastics with biodegradable agricultural feed stocks to meet the requirements of responsible and ecologically sound utilization of resources. This will reduce our dependence on depleting petrochemical resources.