ABSTRACT
Human society beneted from the use of polymers since approximately 1600 BC when the ancient Mesoamericans rst processed natural rubber into balls, gurines, and bands (Hosler et al., 1999). In 1862, Alexander Parkes unveiled the rst man-made plastic in the Great International Exhibition at London. He dubbed the material as “Parkesine,” now called as celluloid. In 1907, chemist Leo Hendrik Baekland, while striving to produce a synthetic varnish, stumbled upon the formula for a new synthetic polymer originating from coal tar. He subsequently named the new substance “Bakelite.” By 1909, Baekland had coined “plastics” as the term to describe this completely new category of materials. The rst patent for polyvinyl chloride (PVC), a substance now used widely in vinyl
CONTENTS
12.1 Introduction ...................................................................................................................... 341 12.2 Plastics and Its Types .......................................................................................................342 12.3 Hazards of Plastics ...........................................................................................................347 12.4 Degradation of Plastics ....................................................................................................347 12.5 Biodegradation of Plastics ...............................................................................................349 12.6 Factors Affecting Plastic Degradation ...........................................................................350 12.7 The Role of Microbes in Biodegradation ....................................................................... 352 12.8 The Role of Enzymes in Biodegradation .......................................................................353 12.9 Characterization of Plastic Degradation .......................................................................353 12.10 Biodegradation of Natural Plastics ................................................................................ 357 12.11 Biodegradation of Synthetic Plastics ............................................................................. 358
12.11.1 Polyethylene ......................................................................................................... 358 12.11.2 Polypropylene ..................................................................................................... 359 12.11.3 Polyvinyl Chloride ..............................................................................................360 12.11.4 Polystyrene ..........................................................................................................360 12.11.5 Polyurethane .......................................................................................................360
12.12 Composting ....................................................................................................................... 361 12.13 Molecular Aspects on Degradation ............................................................................... 362 12.14 Conclusions .......................................................................................................................363 References .....................................................................................................................................363
siding and water pipes, was registered in 1914. Plastics served as substitutes for wood, glass, and metal during World War I and-II. After the Second World War, newer plastics, such as polyurethane (PU), polyester, silicones, polypropylene (PP), and polycarbonatejoined polymethyl methacrylate and polystyrene (PS) and PVC in widespread applications. Plastics have come to be considered “common”—a symbol of the consumer society (American Chemistry Council, Inc., 2011). The history of manufactured plastics goes back more than 100 years; however, plastics are relatively modern when compared with other materials. Development of modern plastics really expanded in the rst 50 years of the twentieth century, with the synthesis of 15 new classes of polymers. Plastics have a range of unique properties: they can be used at a very wide range of temperatures; they are chemical-and light resistant.
