Explain Thermoplastic materials.
Thermoplastic materials: The properties of such plastic materials do not change considerably when they are melted and after that cooled and solidify. They can be repeatedly dissolved or melted in various solvents. They are additional elastic, less brittle and do not lose elasticity while subjected to prolonged heating. They are less apt to age thermally. Again and again they can be remoulded in any shape after heating. Several of them possess extraordinary high insulating properties and they are water repellent. They are polymers of linear structure that is their molecules are elongated and are like thread. This, kind of structure is soluble, fusible, highly plastic, able of forming thin flexible threads as well as films. Illustrations are Polytetra Flouroethylene (P.T.F.E. or Teflon) and Polyvinyl Chloride (P.V.C.).