Acetylation of Native Starch for Production of Biodegradable Plastics

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ABSTRACT
For many years, the use of natural polymers for the fabrication of packaging materials has been an interesting alternative to replace non-biodegradable polymers which are normal components of these materials. The core problem of these starch based plastics is their hydrophilic character and the fact that they tend to become brittle with ageing. Unmodified starch is too much hydrophilic to be used as food packaging material. Chemical modification must be carried out in order to make them hydrophobic. These modifications are grafting, alkylation-especially esterification including acetylation. The purpose of the project is to prepare acetylated starches/starch esters of different Degree of Substitution using different concentrations of acetic anhydride for modifying the native starch. The testing of samples is done by testing various properties of the obtained samples such as Degree of Substitution, Solubility, Swelling Power, Light Transmittance and Water Binding Capacity.

INDEX

1. Introduction ………………………………………………………7 2. Literature Survey………………………………………………….9 3. Biodegradation…………………………………………………..14 4. Biopolymers……………………………………………………..21 5. Starch…………………………………………………………….24 6. Physiochemical Properties of Modified Starch………………….28 7. Experiment………………………………………………………35 8. Results…………………………………………………………...40 9. Discussion……………………………………………………….42 10. Conclusion……………………………………………………….47 11. Future Scenario of Biodegradable Polymers…………………….48 12. References……………………………………………………….49.

Chapter 1
INTRODUCTION
Plastic is the general term for a wide range of synthetic or semi-synthetic polymerization products. They are composed of organic condensation or addition polymers and may contain other substances to improve performance or economics. There are many natural polymers generally considered to be "plastics". Plastics can be formed into objects or films or fibers. Their name is derived from the fact that many are malleable, having the property of plasticity Plastic can be classified in many ways, but most commonly by their polymer backbone (polyvinyl chloride, polyethylene, polymethyl methacrylate, and other acrylics, silicones, polyurethanes, etc.). Other classifications include thermoplastic, thermoset, elastomer, engineering plastic, addition or condensation or polyaddition (depending on polymerization method used), and glass transition temperature or Tg. Plastics are durable and degrade very slowly. In some cases, burning plastic can release toxic fumes. Also, the manufacturing of plastics often creates large quantities of chemical pollutants.

For many years, the use of natural polymers for the fabrication of packaging materials has been an interesting alternative to replace non-biodegradable polymers (polyethylene, polypropylene) which are normal components of these materials. The latter should not be used for short term packaging such as bags, agriculture mulching, bottles, and fast food goods. Natural polymers contribute to the decrease of waste coming from plastics. Research has been done on biodegradable plastics that break down with exposure to sunlight (e.g. ultra-violet radiation), water (or humidity), bacteria, enzymes, wind abrasion and some instances rodent pest or insect attack are also included as forms of biodegradation or environmental degradation. It is clear some of these modes of degradation will only work if the plastic is exposed at the surface, while other modes will only be effective if certain conditions are found in landfill or composting systems. Starch powder has been mixed with plastic as a filler to allow it to degrade more easily, but it still does not lead to complete breakdown of the plastic. Some researchers have actually genetically engineered bacteria that synthesize a completely biodegradable plastic, but this material is expensive at present e.g. BP's Biopol. BASF make Ecoflex, fully biodegradable...
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