Molecular composites of poly(p-phenylene terephthalamide) anion and poly(ethylene oxide):: Thermal behavior and morphology

Molecular composites, in which a small concentration of ionically modified poly(p-phenylene terephthalamide) (PPTA) is dispersed in a poly(ethylene oxide) matrix, have been prepared. With the content of PPTA anion increasing to about 5 wt %, the glass-transition temperature rises and the melting temperature decreases. From the equilibrium-melting-temperature depression data that were obtained from Hoffman-Weeks plots, the Flory-Huggins interaction parameter was determined to be negative (-1.10). These indications of enhanced miscibility between the components are attributed to intermolecular ion-dipole interactions. The presence of rigid PPTA-anion reinforcement alters the morphology; for example, the spherulite size is reduced, and the degree of crystallinity is lowered. Possible models of how the reinforcement is incorporated into the composite are presented. (C) 2000 John Wiley & Sons, Inc.