Crystallization kinetics of poly( p-phenylene sulphide): the effect of branching agent content and endgroup counter-atom

The crystallization behaviour of poly(phenylene sulphide) (PPS) has been studied as a function of branching agent (trichlorobenzene) concentration in polymerization, and as a function of the chemical nature of the endgroup counter-atom. In both cases, the bulk crystallization phenomena could be described by the Avrami equation with exponent n ≈ 3. An increase of the branching agent concentration in polymerization caused decreases of the linear crystal growth rate, overall rate of bulk crystallization, nucleation density, and heat of crystallization. The effect of branching on the linear crystal growth rate seemed to be more important than that of molecular weight. The chemical nature of the endgroup counter-atom affected the kinetic parameters in different ways. The endgroup counter-atoms considered were hydrogen, calcium, zinc and sodium. In decreasing order, the crystal growth rates were found to be PPSCa > PPSH > PPSZn > PPSNa. However, the overall rates of bulk crystallization and the estimated nucleation densities followed the order PPSH > PPSZn > PPSCa > PPSNa. The nucleation densities accounted for the different rates of bulk crystallization. The crystallinity content of PPSH seemed to be lower than those of PPSZn, PPSCa, and PPSNa. While the lower crystallinity content of PPSH could be rationalized by considering the ionic character of the endgroups, it was not possible to account systematically for the nucleation and growth rate dependencies on the nature of the endgroup counter-atom.