Plastics have become an essential necessity in all aspects of today’s modern life. The word plastic is a common term that is used for many materials of a synthetic or semi-synthetic nature. The term was derived from the Greek plastikos, which means “fit for molding.”Plastics are replacing most of the materials due to good mechanical, thermal and chemical properties. Plastics have enormous applications. Plastics have found an enormous space in Industrial Product, Mechanical, electrical, Electronic and Electro-mechanical products. Plastics are influencing on various products ranging from telecommunication equipment, transportation, housing and Fast-Moving Consumer Goods (FMCG) appliances, clothing and commercial market. The list could go on and on and it is obvious that much of what we have today would not be possible without plastics. Plastics are natural or synthetic materials. They are produced by chemically modifying natural substances or are synthesized from inorganic and organic raw materials. On the basis of their physical characteristics, plastics are usually divided into thermosets, elastomers and thermoplastics. These groups differ primarily with regard to molecular structure, which is what determines their differing thermal behavior.
The characteristics of thermosets are hard and have a very tight-meshed, branched molecular structure. Curing proceeds during shaping, after which it is no longer possible to shape the material by heating. Further shaping may then only be performed by machining. Thermosets are used, for example, to make light switches. While elastomers also have a crosslinked structure, they have a looser mesh than thermosets, giving rise to a degree of elasticity. Once shaped, elastomers also cannot be reshaped by heating. Elastomers are used, for example, to produce automobile tires. For the Thermoplastics, it has a linear or branched molecular structure which determines their strength and thermal behavior; they are flexible at ordinary temperatures. At approximate 120 – 180°C, thermoplastics become a pasty or liquid mass. The service temperature range for thermoplastics is considerably lower than that for thermosets. The thermoplastics polyethylene (PE), polyvinyl chloride (PVC) and polystyrene (PS) are used, for example, in packaging applications.