Comb-like copolymer dispersant for PP/CaCO3 composites: effects of particle concentration on properties of composites

Abstract A comb-like copolymer poly (styrene-co-maleic anhydride)-graft-poly (ε-caprolacton) (SMA-g-PCL, SP) with carboxyl group as an anchoring group and polycaprolactone as a solvent chain was used as an effective dispersant for CaCO 3 in the polypropylene (PP) matrix. The effects of CaCO 3 concentration on crystallization behaviors, mechanical properties, and thermal stabilities were studied systematically. The results revealed that the dispersion of CaCO 3 in the PP matrix was markedly improved owing to the steric hindrance effect caused by PCL, and the SP-coated CaCO 3 was a very effective nucleating agent for PP. Proper CaCO 3 concentration corresponded to the improvement of crystallization temperature, crystallinity, and crystallization rate of PP. There was only a slight improvement in yield stress but great improvement in Young’s modulus, flexural modulus, and impact strength. However, the excessive CaCO 3 filler deteriorated the mechanical properties. The good dispersion of SP-coated CaCO 3 in the PP matrix also accounted for the improvement of thermal stability. The initial decomposition temperature of the PP/CaCO 3 composite with 7.4 wt.% CaCO 3 increased 35°C compared with neat PP.