THE EFFECT OF INTERFACIAL INTERACTIONS ON THE RHEOOPTICAL BEHAVIOR OFCOMPATIBILIZED POLYSTYRENE LOW-DENSITY POLYETHYLENE STYRENE-ETHYLENE-BUTYLENE-STYRENE COPOLYMER BLENDS

The influence of styrene-ethylene-butylene-styrene (SEBS) triblock cop olymers on the interfacial interactions in heterogeneous polystyrene/l ow-density polyethylene (PS/LDPE) blends was studied by simultaneous F ourier transform infra-red (FTi.r.) spectroscopic and stress-strain (r heo-optical) measurements. Values of the dichroic ratio (DR) for a spe cific absorption band of the dispersed LDPE phase were determined from the polarized spectra as a function of extension (lambda), and were t aken as a measure of the molecular orientation of the LDPE. A linear r elationship between DR and In lambda was found, and the slope was inte rpreted as a reflection of the interfacial interactions in the heterog eneous blends. The slope increased with the amount of a low-molecular- mass SEES which was added, but was less affected by the addition of a high-molecular-mass SEES. The difference was explained by a lower conc entration of the high-molecular-mass copolymer at the interphase. Copy right (C) 1996 Elsevier Science Ltd.