Crystallization, shrinkage and mechanical characteristics of polypropylene/CaCO3nanocomposites

Abstract

Nanocomposites based on polypropylene (PP) containing 5–15 wt% of nano-calcium carbonate (CaCO3) particles and 1–3 wt% of maleated PP as compatibilizer were prepared by melt compounding followed by injection molding. The crystallinity, shrinkage behavior and mechanical properties were characterized, and the morphology was studied using scanning electron microscopy. Inclusion of 5 wt% of nano-CaCO3interfered with PP crystallization and lowered the thermal contraction. Incorporation of higher fraction of nano-CaCO3(10 wt%) raised the effective ability to nucleate PP crystals and hence increased the crystallization and shrinkage rates. The presence of 10 wt% CaCO3nanoparticles raised the impact strength and elongation at break to as high as 77.4% and 115%, respectively, when compared with pure PP. A trend of CaCO3particles agglomeration was observed at 15 wt% loading that led to the reduction in crystallinity and elongation at break.