Novel Comb-Like Copolymer Dispersant for Polypropylene/CaCO3 Composites and Its Influence on Dispersion, Crystallization, Mechanical, and Thermal Properties

ABSTRACT A novel comb-like copolymer with carboxyl group as an anchoring group and polycaprolactone as a solvent chain was first used as the dispersant of CaCO3 particles in polypropylene (PP). The dispersion of CaCO3 particles in PP matrix was significantly improved in the presence of comb-like copolymer dispersant because of the strong repulsive force caused by steric hindrance effect. The influences of the coating amount of comb-like copolymer dispersant on crystallization behaviors, mechanical properties, and thermal stabilities were systematically investigated. The crystallization temperature, crystallinity, and crystallization rate of PP/CaCO3 composites prepared with monolayer-coated CaCO3 were all improved, where the monolayer comb-like copolymer coating remained as a rigid layer and provided a noticeable nucleating effect. The PP/CaCO3 composites coated with monolayer SP comb-like copolymer also had the best mechanical properties, including tensile strength, Young’s modulus, flexural modulus, and impact strength because of the good dispersion of CaCO3 particles in PP matrix. The thermal stability of PP/CaCO3 composites were measured by thermogravimetric analysis. The results showed that SP comb-like copolymer dispersant treated CaCO3 filled composites had excellent thermal stability than untreated and neat PP, especially for the composite prepared with monolayer-coated CaCO3. GRAPHICAL ABSTRACT