Polymer morphology and crystallisation

Abstract

The basic mechanisms of crystallisation in polymers and copolymers are reviewed and compared with those of other classes of materials. It is shown that, with one possible exception, polymers generally crystallise by secondary nucleation, like other covalent materials. In the case of polymers, however, the behaviour is dictated by the fact that polymers are essentially strings, rather than isolated atoms, in the molten state resulting in more complex behaviour, with regard to the detailed mechanism of crystallisation, the resultant structures generated and the actual unit cells. In the case of copolymers, most unit cells exclude the second monomer, which therefore must be ejected from the growing crystal face for crystallisation to proceed, resulting in an exponential drop in the crystallisation rate with comonomer content.