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)

Abstract

Blends of carboxyl functionalized poly(phenylene sulfide) (PPS) and poly(ethylene terephthalate) (PET) were shown to undergo an ester interchange reaction during melt blending. Pendent carboxyl functionality randomly incorporated along the PPS chain reacts with the ester moiety of PET to form a graft copolymer. A model compound, 2,4-bis(phenylthio benzoic acid), has been synthesized to assist in defining the level of carboxyl functionality on the PPS chain. Evidence of the grafting reaction has been gathered from infrared spectroscopy, solubility measurements, and electron microscopy. When added to blends of PPS and PET homopolymers, the graft copolymer significantly reduces the average domain size of the dispersed phase across the entire composition range. This study describes the role that graft copolymers formed by ester interchange reactions can play in compatibilizing this immiscible blend system, with particular focus on the conditions leading to increased grafting efficiency. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3473–3485, 1999