PROCESSING CHARACTERISTICS OF PSU/PC BLEND ASSOCIATED WITH DEGRADATION IN INJECTION MOLDING

摘要

This study investigates the effect of degradation of the PSU/PC blend (SMA-8~(TM)) on quality characteristics of the molded parts. Experiments were conducted at two sets of melt temperatures - 'normal' temperature, where no severe degradation is expected (T-zone 1); and 'elevated' temperature, where significant degradation should occur (T-zone 2). ASTM D638 tensile bars were used for molding and measured for quality parameters of part weight, warpage, and tensile strength. Small fluctuations in the process variables were purposely introduced for T-zone 1 and T-zone 2. As the results, T-zone 1 provided more consistent shot-to-shot part properties and less process disturbances for all the parameters than T-zone 2. The subsequent baking of the molded parts rendered most of the parts excessively warped for T-zone 2. Back pressure was an important variable regarding shot-to-shot variations in all the parameters.