Abstract
In this study, we manufactured the HDPE/micro-calcium carbonate (CaCO3) composites. A twin screw extruder was used to melt blend different loadings of CaCO3 masterbatch, from 5% to 20%, with HDPE. Furthermore, injection-molded samples were manufactured using different molding conditions, namely pressure and cooling time. The presence of CaCO3 increased the viscosity and the stiffness of the composites. The viscoelastic analysis indicated that adding more than 15% on the CaCO3 masterbatch apparently affected the way the material behaves, as indicated by an abrupt change of some properties of the composite containing 20% masterbatch. As the molding pressure and cooling time increased, the shrinkage of the molded samples decreased. The tensile strength and the ductility of the composite decreased as the content of the CaCO3 increased and as the cooling time or the molding pressure decreased. The fracture surface of all samples had the characteristic dimples of polyethylene fracture; however, neat resin showed extensive fibrillation which was absent at high loadings of CaCO3.