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 ox ide) matrix, have been prepared. With the content of PPTA anion increasing to about 5 wt %, the glass-transition temperature rises and the melting tem perature decreases. From the equilibrium-melting-temperature depression dat a that were obtained from Hoffman-Weeks plots, the Flory-Huggins interactio n parameter was determined to be negative (-1.10). These indications of enh anced miscibility between the components are attributed to intermolecular i on-dipole interactions. The presence of rigid PPTA-anion reinforcement alte rs the morphology; for example, the spherulite size is reduced, and the deg ree of crystallinity is lowered. Possible models of how the reinforcement i s incorporated into the composite are presented. (C) 2000 John Wiley & Sons , Inc.