Naib Tehsildar syllabus : Logical reasoning and Mental Ability | PVS Cla...

i m just trying 1st time

Starch is a linear polymer (polysaccaride) made up of repeating glucose groups linked by

glucosidic linkages. There are two major molecules in starch – amylose and amylopectin.

The alpha linkage of amylose starch allows it to be flexible and digestible. Starch-based biodegradable plastics may have starch contents ranging from 10% to greater than 90%. As the starch content is increased, the polymer composites become more biodegradable and leave less recalcitrant residues, further chemical modification can significantly improve hydrophilicity, as well as change other rheological, physical, and chemical properties of starch. Biodegradation of starch based polymers is a result of enzymatic attack at the glucosidic linkages between the sugar groups leading to a reduction in chain length and the splitting off of sugar units (monosaccharides, disaccharides and oligosaccharides) that are readily utilised in biochemical pathways. Starch-based biodegradable polymers are potential for applications in biomedical and environmental fields. They offer a possible alternative to traditional materials when recycling is unpractical or not economical or when environmental impact has to be minimized. In this paper the recent progress about the preparation of Starch-based biodegradable polymers via physical blending and chemical modification is reviewed and discussed. Starch –PVA films were prepared and changes in properties were evaluated by tensile strength and elongation.