On the effect of a secondary process on the course of polymer crystallisation. Part 3

A crystallisation rate equation which allows for a secondary process involving an increase in crystallinity with logarithmic time has been derived. The model involves volume relaxation of the amorphous material constrained between crystalline regions and considered to relax as a glass. In general the equation predicts values of the Avrami exponent which are fractional, but in practice the equation cannot account for the range of values observed experimentally with polyethylene.