Plastication Influence on the Polymer Rheological Properties in Injection Moulding of Polycarbonate

The main objective of this paper is to evaluate the influence of the plastication phase in the injection moulding process on the rheological properties of polycarbonate. The study is divided into two phases: the first one aims at determining if the plastication process influences the melt viscosity while the second one is devoted to evaluate the influences of the main plastication parameters (melt temperature, residence time and screw rotational speed) on the rheological behaviour. An all-electric injection moulding machine and a twin bore capillary rheometer were used respectively to mould the specimens and to perform the rheological tests. A critical analysis of the results demonstrates that the plastication phase and, in particular, the melt temperature reduces polycarbonate viscosity.