Biodegradable Plastic from Cassava (Manihot Esculenta) Starch

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ABSTRACT
The study aims to produce biodegradable plastic using cassava starch as its main component. Cassava starch was mixed with water, epoxydized soya bean oil (ESBO), glycerol, and polyvinyl alcohol (PVA). The mixture was then compressed and tested. Three preparations were made from the mixture. The first preparation contained 50 grams starch, 50 grams water, 50 grams PVA, 2.5 grams ESBO, and 2.5 grams glycerol. The second preparation contained 65 grams starch, 65 grams water, 50 grams PVA, 2.5 grams ESBO, and 2.5 grams gycerol. The third preparation contained 80 grams starch, 80 grams water, 50 grams PVA, 2.5 grams ESBO, and 2.5 grams gycerol. The first preparation exhibited the most desirable mechanical properties. The material produced was proven to be biodegradable.

INTRODUCTION

There is an increasing demand for plastic, from the highly technological fields of electronics, fiber optics, and pharmaceuticals to the basic necessities such as sandwich wrappers and garbage bags. This high demand for plastics, however, has been a major contributor to the world's present garbage problems. The researches _ AZ1 aimed at developing biodegradable plastics is one big step to lessen, if not total eliminate, this global concern. The use of biodegradable plastics has already started in the United States. Some plastics use cornstarch as an additive. This additive helps in the natural decomposition of the plastic materials. Cassava is basically composed of starch. Cassava starch is composed of two components: amylose and amylopectin. An amylose is a long straight chain of polymer of anhydroglucose units. An amylopectin is a branched chain compound, also of anhydroglucose units.

Because plastics are made of polymers, starch is a very favorable raw material in plastic-making. The study was limited to one species of cassava, Manihot esculenta. The plastic produced was treated with different amounts of starch, polyvinyl alcohol (binder), epoxidized soya bean oil (stabilizer), and glycerol(plasticizer). The finished product was expected to be comparable to commercial plastics in terms of clarity, reaction to acids and bases, water absorption, tensile stress and tensile strain, electrical conductivity and flammability.

REVIEW OF RELATED LITERATURE

The word plastic came from the Greek word plastikos, meaning capable of being molded. Plastics can be as hard as metal or as soft as silk. They can take any shape in almost any form due to the versatility of the carbon, the most common backbone of polymer chains. Plastics can be conveniently divided into two categories: semi-synthetic, in which the basic chain structure is derived from a natural product, such as cellulose; and synthetic, which is built up chemically from small units or monomers. Despite the various applications of plastics, drawbacks have been encountered in three major points. Firstly, there are certain chemicals used in the manufacture of .plastics that may cause allergic reactions. Three is a need man from these threat. Secondly, since cellulose films are biodegradable; they are readily attacked by bacteria. Films and packaging materials from synthetic polymers are normally attacked at a very low rate. New polymers such is nylon, polyvinyl chloride and Polystyrene have replaced cellulose, the pioneer plastic material. As a result, these plastic materials have become permanent wastes.

There 'are various methods in making biodegradable plastics. The simplest is the production of plastic from the extraction of casein from milk. Casein is obtained in two ways by souring, with the use of lactic acid, arid by boiling together with an additive, such as acetic acid.

Starch is a natural organic polymer manufactured by green plants through photosynthesis s to serve as metabolic reserve It occurs in the form of grains in many 'parts of the plant, principally in embryonic tissues such as seeds, fruits, roots and tubers.

Polyvinyl alcohol is a colorless, odorless,...
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