POLYMER CRYSTALLIZATION - ROLE OF METASTABILITY AND THE CONFLUENCE OFTHERMODYNAMIC AND KINETIC FACTORS

Consideration is given to the effect of size on the thermodynamic stab ility in situations where two or more phase variants compete in the co urse of a phase transformation. It is found that, pending on material parameters, a situation can arise where the stabilities of the competi ng phases invert with size. Such a size induced stability inversion ca n have a profound influence on phase development in general connecting also with the kinetics of the phase transformation. Specifically, thi s newly considered combination of interrelated thermodynamic (stabilit y) and kinetic (rates) factors can provide an explanation for the freq uently experienced dominance of metastable phases (the century old Ost wald Stage Rule). When applied to polymers, as in the example of polye thylene, it provides a new outlook for polymer crystallisation. Amongs t others it creates a unified approach for the two, so far largely dis connected areas of chain folded and extended chain type crystallisatio n incorporating (not contradicting!) existing approaches within a wide ned framework.