Polymers -an Introduction and Applications

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Chapter 1 INTRODUCTION The word polymer is derived from the classical Greek words ‘poly’ which means many and ‘mers’ which means parts. Simply stated, a polymer is a long chain molecule that is composed of a large number of repeating units of identical structure. Polymer is a molecule of high relative molecular structure of which essentially comprise the multiple repetitions of units derived, actually or conceptually, from molecules of low molecular mass. Certain polymers, such as proteins, cellulose and silk are found in nature, while many others, including polystyrene, nylon etc., are produced only by synthetic routes. If one discounts the end uses, the differences between all polymers, including plastics, fibers and elastomers or rubbers, are determined primarily by the intermolecular and intramolecular forces between the molecules and within the individual molecule, respectively and by the functional groups presents. Polymers are used in a wide range of applications such as packaging, textile, adhesives, commodity, engineering materials etc. Polymers are of lightweight, high strength, resistance to chemicals and highly flexible. They can be easily moulded to any shapes. They are cheaper in cost and amenability for quick and mass production. These factors made polymer to suit for variety of application. Cellulose nitrate in a mixture of ethanol and ethyl ether is still used as a liquid plaster. The next generation of polymers, the phenolics, found wide application as structural and insulating materials in electronic devices. 1. CLASSIFICATION OF POLYMERS Polymers can have different chemical structures, physical properties, chemical behaviour, thermal characteristics, etc., and can be classified in different ways, as given below. 1. NATURAL AND SYNTHETIC POLYMERS Depending on their origin, polymers can be

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