Influence of acrylonitrile content in styrene-acrylonitrile copolymer on the phase morphology and interfacial tension in blends of polycarbonate/styrene-acrylonitrile copolymer

We have studied the phase morphology and interfacial tension in blends of PC/styrene-acrylonitrile copolymer (SAN) as representatives of polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) blends. To confirm how the acrylonitrile (AN) content of the SAN polymer influences the phase morphology and rheology, PC/SAN (90/10) blends with varying AN content ranging from 24 to 41 wt% with respect to the SAN were prepared using a twin-screw extruder. The interfacial tension of the blends was determined from the measured average particle radius and the relaxation time of the interface using Palierne’s emulsion model. The minimum interfacial tension and domain size occurred in the blend containing AN 28.5 wt% versus SAN. The interfacial tension results were consistent with the observed morphology and rheology of the blends. Because the viscosity of SAN polymers varied with the AN content and molecular weight, the effect of the viscosity ratio was also examined by Wu’s empirical expression.