Co-Polymer: Two unlike monomers joined together in a polymer chain. E.g. Poly Vinyl Acetate
Lubricants: Make the polymer easier to mould. Various types of waxes are used in small amounts.
Pigments: Give the Polymer colour
Vulcanisation: Natural rubber is processed with sulphur to form cross links between chain molecules to improve wear resistance and life. It is less flexible that natural rubber which is soft.
Van Der Waals Forces: Weak secondary bonds. May be disrupted by heat.