NATURE OF THE ANOMALOUS SHAPE CHANGE IN LOSS PERMITTIVITY VERSUS FREQUENCY CURVE OF POLYMERS ABOVE AND NEAR THE GLASS-TRANSITION TEMPERATURE

A simple theory has shown that loss permittivity due to the micro-Brownian motion of macromolecules in amorphous region of crystalline polymers is governed by the distribution of fractional free volume as well as that of relaxation times at a constant fractional free volume. Further investigation is carried out to clarify the roles of these two types of distribution. For this purpose, Γ-distribution is used for the distribution of fractional free volume, while the Debye-type decay function and the Williams-Watts' decay function are employed for the distribution of relaxation times. The comparison between the calculated and experimental values reveals that the former distribution determines substantially the shape of loss permittivity versus frequency curve near Tg, while the latter plays an essential role for the shape of this curve at temperatures much higher than Tg. © 1990 The Japan Society of Applied Physics.