Simulation of the Fiber Orientation of Kevlar in SPS/Kevlar Composites- Effect of Fluorination and Oxy-fluorination of Kevlar Fiber on the Properties and Processibility

摘要

The Kevlar fiber was fluorinated and oxy-fluorinated directly in presence of fluorine and blended with SPS at 300°C under 10 rpm in a twin-screw extruder. The composites were then injection molded into dumbbell shaped specimens under different conditions like various mold temperatures,injection temperatures, injection speeds and mold filling rates. Various physico-chemical characterizations of the composites have been done and effect of all the processing parameters and the chemical modifications were studied. The properties were correlated with the fiber orientations that have been computer simulated by mold flow technique. It has been found out that the processibility differ widely with the variation of processing parameters during injection molding. The orientations are different in the skin and core region, which once again affects the flow behavior. The bulk technical properties were found to be the function of the fiber orientations in skin and the core of the injection molded samples. The enhanced mechanical property are also observed in case of modified composites resulting better fiber/matrix interaction at the interface due to the incorporation of the functional groups onto the Kevlar surface. Scanning electron microscopy reveals the better fiber/matrix adhesion in case of modified fiber reinforced syndiotactic polystyrene composites. It is worth mentioning that the maximum fiber orientation occurred during the extrusion process at the wall but different extent of fiber orientation is obserbed during the injection moulding depending on the shape of the dumbbell specimen.