Plastics are also called synthetic resins and are broadly classified into two categories:
Thermosetting resins and thermoplastic resins.
The thermosetting resins include phenolic resin and melamine resin, which are thermally hardened and never become soft again. Thermoplastic resins include PVC, Usually, thermoplastics are supplied in the form of pelletised material (compounds) with additives (antioxidants, etc.) already blended in it. However, PVC resin is often supplied in powder form and long term storage is possible since the material is resistant to oxidation and degradation.
Various additives and pigments are added to PVC during the processing stage, and the blend is then converted into PVC products.
PVC is a thermoplastic made of 57% chlorine (derived from industrial grade salt) and 43% carbon (derived predominantly from oil / gas via ethylene). It is less dependent than other polymers on crude oil or natural gas, which are nonrenewable,and hence can be regarded as a natural resource saving plastic, when PVC is set on fire, the flames go out as the fire source is removed due to the material’s self-extinguishing properties.