The molecules of copolymers consist of monomers or polymer segments of different chemical natures. Copolymerisation with a strange polymer or monomer can significantly change the properties of a base polymer. Different copolymers are classified as plastic types of their own. Examples:
- ABS = acrylonitrile butadiene styrene
- EVA = Ethylene-vinyl acetate The weight percentages of ethylene and vinyl acetate can be freely determined, and thus the properties of the plastic from rigid (100% ethylene) to elastic like rubber with a high vinyl acetate percentage.
A differentiation must be made between a copolymer and blends, which are homogeneous mixtures of different polymers but do not form copolymers.