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In this study three grades of rigid poly vinyl chloride (PVC) having different molar masses were melt blended with graft-acrylonitrile-butadiene-styrene (g-ABS) in different compositions. The effect of PVC molecular weight and g-ABS composition on the compatibility and Izod impact strength of the blends were investigated. Differential scanning calorimetry (DSC) results showed a single glass transition temperature (Tg) for all the blends, representative of miscibility between the PVC phase and the styrene-acrylonitrile copolymer (SAN) phase of g-ABS which, in turn, led to compatibility of the PVC/g-ABS blends. It was observed that in all the PVC grades the blends Izod impact strength increased with increasing g-ABS content. Also, at a given composition of g-ABS, by increasing the molecular weight of the PVC phase the impact strength of the blends increased. The morphology of the fracture surfaces from the impact tests were analyzed using scanning electron microscopy (SEM) micrographs and the results showed that with increasing g-ABS content in the blend, cloudy regions increased and eventually begin to overlap each other, and the deformed material on the fracture surfaces increased. This was attributed to the blend compatibility causing greater energy dissipation in the fracture process. [ABSTRACT FROM AUTHOR]

The low-velocity, low-energy impact response of optical-grade polycarbonate (PC) was characterized by the Izod impact testing at ambient temperature. The following factors affecting impact response were investigated: mold temperatures (80, 90, 100, 110, and 120°C) and annealing treatment (120°C for 12 h). The results showed that the annealing treatment remarkably reduced the impact strength. The maximum impact strength was obtained when the mold temperature was 100°C for both unannealed samples and annealed ones. Moreover, the annealing treatment changed the failure mode of specimens from ductile failure to brittle failure, which was confirmed by fracture morphology analysis using scanning electron microscopy (SEM). The ductile failure was attributed to shearing behavior, and the fracture surfaces were rough and irregular with many river-shaped striations. The brittle fracture was caused by a craze failure mechanism. The brittle fracture sections could be divided into three regions: fracture origin, mist region, and end-wall banded region. [ABSTRACT FROM PUBLISHER]