Polymer crystallisation : role of metastability and the confluence of thermodynamic and kinetic factors

Consideration is given to the effect of size on the thermodn. stability in situations where 2 or more phase variants compete in the course of a phase transformation. It is found that, depending on material parameters, a situation can arise where the stabilities of the competing phases invert with size. Such a size-induced stability inversion can have a profound influence on phase development in general connecting also with the kinetics of the phase transition. Specifically, this newly considered combination of interrelated thermodn. (stability) and kinetic (rates) factors can provide an explanation for the frequently experienced dominance of metastable phases (the century-old Ostwald Stage Rule). When applied to polymers, as in the example of polyethylene, it provides a new outlook for polymer crystn. Amongst others it creates a unified approach for the 2, so far largely disconnected areas of chain folded and extended chain type crystn. incorporating (not contradicting!) existing approaches within a widened framework