Structural Gradients in Injection Molded PPS

Abstract

Abstract The processing-structure-property relationships in injection molded poly-p-phenylene sulfide (PPS) has been investigated. The structural gradients developed in the molded parts were characterized using optical microscopy, differential scanning calorimetry and wide angle X-ray diffraction techniques. Generally amorphous parts are produced with cold molds and crystalline parts with hot molds. At intermediate mold temperatures the parts produced exhibit a glassy surface and core and a crystalline annular ring sandwiched in between. The characteristics of this crystalline ring formation were studied as a function of processing conditions and position in the molded parts. Tensile and impact properties of the injection molded parts were correlated with the processing conditions and structure. The samples containing crystalline rings were found to exhibit greater toughness and tensile strength as compared to the samples that are uniformly amorphous or uniformly crystalline.