Investigation of the microstructures, properties, and toughening mechanism of polypropylene/calcium carbonate toughening masterbatch composites

ABSTRACT The morphologies, crystallization and melting behaviors, and mechanical, thermal and processing properties of polypropylene (PP)/CaCO3 toughening masterbatch (CTM) composites were investigated. The good dispersion of CaCO3 particles via appropriate surface encapsulation in the composites is proven by density measurements and scanning electron microscopy images. The crystallinity and tensile strength of PP decrease with the addition of CTM. The flexural modulus and storage modulus (E′) at 23 °C increase with CTM content, implying improved stiffness. A sharp increase in the Izod notched impact strength can be observed for the composites, and the critical ligament thickness (τc) is calculated to be 1.31 and 2.46 μm for PP (S1003) and PP (001 G) composites, respectively. The morphologies of the impact‐fractured surfaces of the specimens were observed, and the shear deformation is enhanced by the addition of CTM. The presence of CTM also increases the melt flowability and decreases the shrinkage of the composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45515.