EFFECTS OF THE MOLECULAR-STRUCTURE OF STYRENE-ISOPRENE BLOCK-COPOLYMERS ON THE INTERFACIAL CHARACTERISTICS OF POLYSTYRENE POLYISOPRENE BLENDS/

The effects of the molecular structure of the styrene-isoprene block c opolymer on the interfacial tension, the morphology and the interfacia l adhesion of polystyrene/polyisoprene were investigated. A reduction in interfacial tension is observed with the addition of a small amount of copolymer, followed by a leveling off as the copolymer concentrati on exceeds the critical micelle concentration. The reduction in interf acial tension between polystyrene and polyisoprene is more significant when the isoprene-rich diblock copolymer is added than the cases when the symmetric or styrene-rich diblock copolymer is added. The interfa cial tension data seem to be consistent with the phase morphology and the interfacial adhesion: the lower the interfacial tension, the small er the domain size of dispersed phase and the better the interfacial a dhesion. (C) 1996 John Wiley & Sons, Inc.