Preparation of organically modified CaCO3 and its use in the manufacture of polypropylene composites

Abstract

The most common filler used in plastics is CaCO3 due to its abundance and low cost. Usually dispersion of particles in a polymer is difficult due to strong tendency of the fine particles to agglomerate. Surface treatment of fillers is a way to modify the interfacial adhesion. In this work, various organic modification agents for CaCO3 are used to provide a hydrophobic surface and, to increase the interfacial adhesion. For this purpose, stearic acid, vinyl acetate, maleic anhydride, paraffin, EVA are used in different combinations and ratios. CaCO3 particles are modified with different ratios of coatings. Appropriate samples are selected for blending and molding with PP. Thermal analysis measurements, surface tension analysis and mechanical test techniques were used to determine the best coating agent. Results indicate that modification of inorganic CaCO3 particles with EVA is a successful way to achieve better dispersion. This enables usage of more inorganic filler in PP without sacrificing the mechanical properties.