POLYSTYRENE POLYCARBONATE POLYSTYRENE-BLOCK-POLYCAPROLACTONE BLENDS - EMULSIFICATION AND MECHANICAL PERFORMANCE

Two polystyrene-polycaprolactone diblock copolymers, of differing molecular weights, have been extrusion-blended with polystyrene and polycarbonate. The morphologies of the resultant blends were studied using differential scanning calorimetry and scanning electron microscopy. In all compositions studied, the polystyrene and polycarbonate phases exhibited discrete glass transitions indicative of the immiscibility of these components. However, addition of the copolymer increased the extent of dispersion of the homopolymer components within one another quite effectively. Blend specimens were tested with respect to tensile, flexural, impact, thermal, and flow characteristics to probe the effects of morphology and composition of these factors. In general, the blends were rigid, brittle materials with thermal characteristics in the range between those of the polystyrene and polycarbonate components. Addition of polystyrene-block-polycaprolactone polymer to the blends resulted in increased brittleness, reduced thermal performance, maintenance of rigidity, and improved flow.