The word plastic is derived from the Greek word plastikos, meaning capable of being shaped or moulded. It refers to their malleability or plasticity during the manufacture that allows them to be cast, pressed or extruded into a variety of shapes.
Plastics are typically polymers of high molecular mass, and the monomers of plastic are either natural or synthetic organic compounds.
Due to their relatively low cost, ease of manufacture, versatility and imperviousness to water, plastics are used in an enormous and expanding range of products, from paper clips to spaceships. They have already displaced many traditional materials such as wood, leather, paper, metal, glass etc.
Types of Plastics
- Thermoplastic: It is also known as thermosoftening plastic. It is a polymer that turns to a liquid when heated and freezes to a very glassy state when cooled sufficiently. Most thermoplastics are high-molecular-weight polymers whose chains are associated by weak van der Waals forces, as in polyethylene, and by stronger dipoleâ€“dipole interactions and hydrogen bonding, as in nylon. Other examples are polyester, polystyrene, polyethylene terephthalate, polyamide etc.
- Thermosetting plastic: A thermosetting polymer is a prepolymer in a soft solid or viscous state that changes irreversibly into an infusible, insoluble polymer network by curing (which is referred to the toughening or hardening of a polymer material by cross-linking of polymer chains). Curing can be induced by the action of heat or suitable radiation, or both. A cured thermosetting polymer is called a thermoset.
Recycling of Plastics
Plastics are not decomposed by microorganisms, i.e. they are not biodegradable. Hence, this leads to pollution, which can be controlled by recycling.
Recycling of plastic is the process of recovering scrap or waste plastics and reprocessing the material into useful products, sometimes completely different in form from their original state.