The word plastic is derived from the greek word “plastikos” meaning fit for moulding. It’s malleable property allows it to be cast, pressed, or extruded into an enormous variety of shapes. (Source: Wikipedia )
Plastics are made of hydrocarbons, typically derived from petroleum or natural gas. Crude oil or petroleum is a fossil fuel (i.e. Coal, petroleum and natural gas), which means it was made naturally from decaying plants and animals. Petroleum contains hydrocarbons, which are molecules containing hydrogen and carbon. Chemically cross-linking different hydrocarbon chains can create plastics, rubber, auto gasoline, diesel fuel, paraffin wax and more. There are two types of plastics: thermoplastics and thermosets. See thermoplastics and thermosets.
Thermoplastics soften when heated and harden when cooled and can then be formed into different shapes. They keep this shape when they cool. They can be reheated several times. Some examples of thermoplastics are the resins: polyethylene (HDPE, LDPE, PE, MDPE, PET), polypropylene (PP), and polyvinylchloride (PVC). This type of plastic is used to make things like yoghurt pots, mobile phones and pop bottles.
Thermosets or Thermosetting Plastics
These plastics are stiffer and stronger than Thermoplastics. It will not soften. Because this plastic does not go soft when heated it can be used to make kettles, electrical plugs and saucepan handles.