Influence of Elastomer Modification on Impact Strength of PP/Elastomer/CaCO3 Composite

Polypropylene (PP)/elastomer/fine filler particle ternary composite was prepared using polystyrene-block-poly(ethylene-butene)-block-polystyrene triblock copolymer (SEBS) or carboxylated SEBS (C-SEBS) as elastomer and calcium carbonate (CaCO₃) having mean size about 160 nm as filler. First, SEBS (or C-SEBS) and CaCO₃ particles were mixed to form master batch. Second, the prepared master batch and PP matrix were kneaded. In the PP/SEBS/CaCO₃ ternary composite, CaCO₃ particles and SEBS particles were dispersed in the PP matrix separately. In the PP/C-SEBS/CaCO₃ ternary composite, CaCO₃ particles were encapsulated in C-SEBS and formed a core–shell structure at lower CaCO₃ concentration; however, some CaCO₃ particles were dispersed in PP matrix at higher CaCO₃ concentration. In the PP/SEBS/CaCO₃ composite, the impact strength increased with the amount of incorporated CaCO₃ particles. Whereas, in the PP/C-SEBS/CaCO₃ composite, the impact strength increased with the amount of CaCO₃ particles dispersed in PP matrix. The master-batch method was found to be useful for improving the dispersibility of CaCO₃ particles than the commonly used single-batch method.