Abstract
Isothermal crystallization kinetics from the mesomorphic state of poly [bis(4-methylphenoxy) phosphazene] (PB4MPP) have been studied by a depolarized light intensity (DLI) technique. Before crystallization, the films of PB4MPP were annealed at programmed temperatures (Tf) above its meso/crystalline phase transition temperature (156.2°C). The observed radial growth rate (G) of PB4MPP spherulite and overall-rate constant (_??_) observed for the film increased with increasing Tf. Avrami exponent (n) of the PB4MPP film crystallized from the mesophase was estimated to be 4 irrespective of various Tfs. This result indicates that the mechanism of PB4MPP spherulitic crystallization from the mesophase is independent of Tf. The interfacial surface free energy term (σσe) for this polymer was estimated in terms of n and _??_. With an increase in Tf, the value of σσe decreased, though the DLI in the mesophase increased monotonically. Thus, raising Tf provides more regularly aligned PB4MPP molecules in the pseudohexagonal state, so that secondary nucleation is induced easily; finally both G and _??_ in. crease with an increase in Tf.
