COMPATIBILIZING EFFECTS OF POLY(STYRENE-GRAFT-ETHYLENE OXIDE) IN BLENDS OF POLYSTYRENE AND BUTYL ACRYLATE POLYMERS

The compatibilizing effect of poly(styrene-graft-ethylene oxide) in po lystyrene (PS) blends with poly(n-butyl acrylate) (PBA) and poly(n-but yl acrylate-co-acrylic acid) (PBAAA) was investigated. No significant effects of the graft copolymer on the domain size were found in the PB A blends. By functionalizing PBA with acrylic acid, the average size o f the polyacrylate domains was reduced considerably by the graft copol ymer. Thermal and dynamic mechanical analysis of the PS/PBAAA blends r evealed that the PBAAA glass transition temperature (T-g) decreased wi th increasing graft copolymer content. The effect of the graft copolym er in the PS/PBAAA blends can be explained by interactions across the interface due to the formation of hydrogen bonds between the poly(ethy lene oxide) (PEO) side chains in the graft copolymer and the acrylic a cid segments in the PBAAA phase. Hydrogen bonding was confirmed by IR analysis of binary blends of PEO and PBAAA. Partial miscibility in the PEO/PBAAA blends was indicated by a PEO melting point depression and by a T-g reduction of the PBAAA phase. The thermal properties of the P EO/PBA blends indicated only very limited miscibility. (C) 1996 John W iley & Sons, Inc.