MELT BLENDS OF SAN WITH PHENOXY

Melt blends of styrene-co-acrylonitrile (SAN) with phenoxy were prepared over a full range of compositions and were evaluated in terms of morphological, rheological, thermal, and mechanical properties. Viscosity-composition plots showed a crossover with the additivity line at 50/50 (SAN/phenoxy by weight), and deviations from semicircles in Cole-Cole plots were seen for 70/30, 50/50, and 30/70 blends. Scanning electron micrographs (SEM) of the blends showed a two-phase morphology with a finer dispersion and well-elongated fibrils seen when SAN formed the dispersed phase. The glass transition temperature (T(g)) of SAN was almost unchanged in the blends, whereas T(g) of phenoxy was increased over 5-degrees-C. Tensile modulus and strength generally showed synergistic effects in phenoxy-rich blends. In the 10/90 blend, the ultimate elongation was greater than for pure phenoxy, and a dramatic drop of Izod impact strength was observed.