NORMALIZATION OF THE TEMPERATURE-DEPENDENCE OF SEGMENTAL RELAXATION-TIMES

The validity of T(G)-scaled Arrhenius plots of segmental relaxation times for glass-forming liquids is assessed by comparing the results on polymers differing only in molecular weight. The differences result in identical segmental relaxation dispersions which occur, however, at different times and temperatures. It is verified herein that the T(G)-normalization scheme is a self-consistent means to classify and distinguish segmental relaxation behavior of polymers. Contrarily, changes in glass transition temperature effected by hydrostatic pressure alter the segmental dynamics in a manner such that the fragility of the polymer is altered.