TERNARY BLENDS OF PHENOXY SAN POLY(EPSILON-CAPROLACTONE)

The compatibilizing effect of poly (epsilon-caprolactone) (PCL) on the blends of two immiscible polymers, poly(hydroxy ether of bisphenol A) (phenoxy) and poly(styrene-co-acrylonitrile) (SAN) has been investiga ted. The phase behavior of the ternary blends was affected by the AN c ontent in the SAN copolymers and a maximum miscible region was observe d at 19.5 wt % of AN. The effect of AN content on the phase behavior o f the ternary blends was interpreted in terms of the relative magnitud e of the segmental interaction energy densities, which were obtained b y combining a melting point depression and an extended binary interact ion model. When a small amount of PCL was added to the phenoxy/SAN ble nds, the phase morphology showed a finer phase dispersion, indicating that the interfacial tension between the phenoxy and SAN is considerab ly reduced. However, the improvement in tensile properties was limited despite the morphological change with the PCL content. From the resul ts of the DSC measurements, SEM, and tensile testing, it was understoo d that the PCL acted as a compatibilizer for the immiscible phenoxy/SA N blends. (C) 1994 John Wiley & Sons, Inc.