Effect of talc/MMA in situ polymerization on mechanical properties of PVC-matrix composites

In this study, polymethyl methacrylate (PMMA)-coated talc was produced by t he in situ polymerization of methyl methacrylate on the talc surface. The p olymerization reaction was performed by both batch and semicontinuous emuls ion processes. The polymerization kinetics, particle size and distribution, grafting efficiency, and coated-talc morphology were systematically invest igated. It was found that the talc particles have no effect on the polymeri zation of PMMA. The PMMA produced was found to cover the talc surface well. However, only a small amount can be grafted onto the talc. The size distri bution of talc particles treated by semicontinuous emulsion polymerization is more uniform than by batch polymerization. The treated talc was subseque ntly used as filler in a poly(vinyl chloride) (PVC) matrix, and mechanical properties of the PMMA-coated-talc/PVC composites were studied. Morphologic al structure of PVC-matrix composites revealed that the PMMA coating on tal c improved the dispersion of talc in the PVC matrix and enhanced the interf acial adhesion between the talc and PVC. The mechanical properties of the c omposites, especially the impact strength, were found to be improved. There appears to be a critical covering thickness of PMMA on the talc surface fo r optimum toughening. (C) 2001 John Wiley & Sons, Inc.