Effect of an acrylic modifier on the brittle to ductile transition in poly(vinyl chloride)

Abstract

AbstractInstrumented notched Izod measurements were made on test specimens cut from milled compression molded plaques of modified and unmodified poly(vinyl chloride) (PVC). The experimental variables were notch radius (from 0.025 to 6.35 mm in 8 steps) and two temperatures (23 and 12.5°C). Load‐time and energy‐time curves were determined under each set of experimental conditions, and each condition was replicated five times. The brittle to ductile transition is readily observed in this experimental range. The transition always occurs at shorter notch radii at each temperature for the modified PVC. In the transition region, the total energy drops from the 1,000 to 2,000 J/m range to less than 150 J/m. In this region, maximum loads remain the same while the times to break becomes much shorter for the brittle materials. These results suggest that the underlying molecular mechanism for brittle failure is the inability of the system to respond to the applied deformation. The oscillations observed in the printed output of the instrumented impact test were identified as having instrument rather than test specimen origins.