Table 1 gives the world production data regarding polyolefins and their copolymers as well as those concerning the other main plastics. As may be inferred from such data, the polyethylenes obtained via catalytic processes and polypropylenes (homopolymers and modified products) rank fourth and fifth in terms of quantities produced. Polypropylene fibres and ethylenepropylene based elastomers rank fourth and fifth in their respective classifications.