Impact strength of PVC-U - effect of calcium carbonate particles size

Unmodified unplasticised PVC (PVC-U) has the disadvantage of being prone to occasional brittleness and is notch sensitive. To increase the impact resistance, a multiphase systems consisting of PVC with various additives such as impact modifiers and fillers were developed and are being used in windows frame formulations. There has been considerable effort and interest in the addition of calcium carbonate fillers to the impactmodified PVC-U formulations to modify properties and also to reduce cost. This paper reports the use of Instrumented Falling Weight Impact tester to determine the effect of calcium carbonate fillers on impact strength of impact-modified PVC-U. Scanning Electron Microscopy analysis had also been carried out to correlate the impact strength and the microstructure of the fracture surfaces. The results show that the impact strength of impact-modified PVC-U increases with decreasing calcium carbonate fillers particle size