Rotational Molding of Polycarbonate Reinforced Polyethylene Composites: Processing Parameters and Properties

Rotational molding has become one of the most important polymer processing methods for producing hollow plastic articles. The goal of this report is to study the rotational molding of polycarbonate (PC) reinforced polyethylene composites. Experiments were carried out on a laboratory scale uniaxial machine, which is capable of measuring internal air temperatures in the cycle. Before molding, PC and polyethylene were blended by a twin-screw extruder. The extrudate was cut into pellets. Polyethylene powder mixed with PC/polyethylene pellets were then mixed by a dry mixer and rotationally molded by a box mold. Characterization of molded part properties was performed after molding. It was found that the impact strength of molded composites increased with the volume fraction of PC reinforcement, whereas the tensile strengths decreased with the reinforcement. Higher cooling rates molded composites with higher impact strengths but lower tensile strengths. There exists an optimum internal peak air temperature with which composites of the highest mechanical properties can be obtained. Additionally, various mathematical models were employed to predict the tensile properties of molded composites, and the Halpin-Tsai-Nielsen model was found to match well with the measured tensile modulus of molded composites. POLYM. ENG. SCI., 50:1457-1465, 2010. (C) 2010 Society of Plastics Engineers