MODELING OF MOISTURE EFFECTS ON THE RHEOLOGICAL BEHAVIOR OF POLYMERS AND INFLUENCES ON THE INJECTION MOLDING PROCESS

摘要

By processing technical polymers like polyamide or polybuthylene terephthalate, possible causes for process variations are residual moisture of the material or different conditions with respect to time and temperature. To show influences on the quality of an injection molding process, the changes have to be measured and described by a rheological model. The material behavior is measured by a rotational rheometer and a high-pressure capillary rheometer at different conditions. Effects like thermal and hydrolytic degradation or viscosity reduction by residual moisture are examined during this investigation. Combining measurements to a rheological model allows the simulation of influences on the processing and compensations. Therefore a new extension of the Carreau-model is presented. Parameters describing the material behavior are completed by a thermodynamic and calorimetric analysis of the material.