Study on Morphology and Mechanical Properties of PVC with Ultrafine CaCO3 Surface-modified by Acrylate Macromolecular Modifiers

In this paper, ultrafine CaCO3 particles were modified by four acrylate macromolecular modifiers, AC730, AC532, AC235 and AC037 with glass transition temperature from low to high, and subsequently added into PVC to investigate their influence on morphology and mechanical properties of the composites. Dispersity tests in organic solvents with different polarities show that modified CaCO3 particles can be well-dispersed in ethyl acetate and dichloromethane whose polarities are close to that of PVC, indicating good compatibility between modified CaCO3 particles and PVC. AC235 and AC037 with more content of "rigid" MMA units have better dispersing effect on CaCO3 particles than AC730 and AC532 with more content of "soft" BA units as revealed by SEM images of modified CaCO3 particles and PVC composites. Moreover, the results of tensile tests show that modified CaCO3 particles have obvious reinforcing and toughening effect on PVC, and the highest tensile strength and elongation at break were observed in the PVC sample modified by AC235. The results of tensile properties tests can be explained on the basis of the variations of interfacial cohesive strength and dispersing state of CaCO3 particles in PVC matrix.