Introduction

It was noted in Chapter 5 (Volume 1) that both the course of fusion and the equilibrium melting temperature depend on the sequence propagation probability parameter, p, and whether the crystalline phase remains pure. It is known that in simple liquids the introduction of a second component significantly alters the nucleation rate and consequently the overall rate of crystallization from the melt. The phase diagrams for such two-component systems govern to a large extent the crystallization process. In copolymers the equivalent of a second component is built into the chain. Hence, changes in the crystallization process of copolymers, relative to homopolymers, can be expected, and are in fact supported by kinetic studies. With copolymers, however, it is the sequence propagation probability rather than the composition that is important.

In this chapter the overall crystallization kinetics and spherulite growth rates of the major copolymer types will be presented and analyzed. It should be recalled from the point of view of polymer crystallization that chains containing structurally different repeating units, although chemically identical, are also treated as copolymers. These include branch points and regio defects as well as stereo and geometric isomers. As a matter of convenience, the influence of cross-links will also be included in this chapter.