Biodegradable Plastics Three generations of starch-based plastics are recognized. The first generation consists of a synthetic polymer. Starch is only used as a filling material it’s polymeric properties are not made use of. An example are "biodegradable" plastic bags. These bags are not fully biodegradable, though, since they consist of mainly non-biodegradable synthetic polymers like polyethylene or polypropene and only 5-20 percent starch. Under special conditions the starch degrades and the plastic falls apart into small particles, that will prevail for many years although they are not visible.

Biodegradable Plastics In the second generation the starch is used for its polymeric properties. It is blended with hydrophilic synthetic polymers and contributes to the strength of the material. 50-80% starch can be used in these plastics, but still a large part is not biodegradable. The third generation is a truly biodegradable plastic, that does not contain synthetic polymers at all. To improve some of the properties of the plastic, the biopolymer may be modified, but no synthetic materials are necessary.[42]

Biodegradable Plastics The barrier properties that are required for a film depend on it’s use. Fresh fruits or vegetables have to be able to breath, so a film with too low an oxygen and/or carbon dioxide permeability can not be used. Foods which are rich in polyunsaturated fat, however, are sensitive to oxygen and need a film with a high oxygen barrier. Often the barrier against water is the most important function of a film, since aw is an important factor for the shelf life of a product (microbial growth, chemical reactions, crispiness).[33]

Hazards Of Plastics Hazards of Plastics: Most of today's plastics and synthetic polymers are produced from petrochemicals. As conventional plastics are persistent in the environment, improperly disposed plastic materials are a significant source of environmental pollution, potentially harming life. The plastic sheets or bags do not allow water and air to go into earth which causes reduction in fertility status of soil, preventing degradation of other normal substances, depletion of underground water source and danger to animal life. In the seas too, plastic rubbish - from ropes and nets to the plastic bands from beer packs -choke and entangle the marine mammals.

Bio Plastics Are Biodegradable Bio plastics are biodegradable plastics, whose components are derived from renewable raw materials. These plastics can be made from abundant agricultural/animal resources like cellulose, starch, collagen, casein, soy protein polyesters are triglycerides. Large-scale use of these would help in preserving non-renewable resources like petroleum, natural gas and coal and contribute to the problems of waste management. Biodegradable plastics degrade over a period of time if exposed to sun and air. Though the demand for biodegradable plastics is increasing, acceptance of biodegradable polymers is likely to depend on factors like Customer response to costs; Possible legislation by governments; and The achievement of total biodegradability.

Plastics That Break Down In an effort to overcome these shortcomings, biochemical researchers and engineers have long been seeking to develop biodegradable plastics that are made from renewable resources, such as plants. The term biodegradable means that a substance is able to be broken down into simpler substances by the activities of living organisms, and therefore is unlikely to persist in the environment. There are many different standards used to measure biodegradability, with each country having its own. The requirements range from 90 per cent to 60 per cent decomposition of the product within 60 to 180 days of being placed in a standard composting environment.

What’s The Cost Unfortunately, as with PLA, PHA is significantly more expensive to produce and, as yet, it is not having any success in replacing the widespread use of traditional petrochemical plastics. Indeed, biodegradable plastic products currently on the market are from 2 to 10 times more expensive than traditional plastics. But environmentalists argue that the cheaper price of traditional plastics does not reflect their true cost when their full impact is considered. For example, when we buy a plastic bag we don’t pay for its collection and waste disposal after we use it. If we added up these sorts of associated costs, traditional plastics would cost more and biodegradable plastics might be more competitive

Pots You Can Plant Another biodegradable plastic product is a plant pot produced by injection moulding. Gardeners and farmers can place potted plants directly into the ground, and forget them. The pots will break down to carbon dioxide and water, eliminating double handling and recycling of conventional plastic containers.

The End By Sam N Liam