Phase separation in semicrystalline blends of poly(phenylene sulfide) and poly(ethylene terephthalate). I. Preparation of poly(phenylene sulfide)-graft-poly(ethylene terephthalate) copolymers by ester interchange and characterization utilizing the model compound 2,4-bis(phenylthio benzoic acid)

Blends of carboxyl functionalized poly(phenylne sulfide) (PPS) and poly(eth ylene tetraphthalate) (PET) were shown to undergo an ester interchange reac tion during melt blending. Pendent carboxyl functionality randomly incorpor ated along the PPS chain reacts with the ester moiety of PET to form a graf t copolymer. A model compound, 2,4-bis(phenylthio, benzoic acid), has been synthesized to assist in defining the level of carboxyl functionality on th e PPS chain. Evidence of the grafting reaction has been gathered from infra red spectroscopy, solubility measurements, and electron microscopy. When ad ded to blends of PPS and PET homopolymers, the graft copolymer significantl y reduces the average domain size of the dispersed phase across the entire composition range. This study describes the role that graft copolymers form ed by ester interchange reactions can play in compatibilizing this immiscib le blend system, with particular focus on the conditions leading to increas ed grafting efficiency. (C) 1999 John Wiley & Sons, Inc.