The structure and morphology of syndiotactic polystyrene injection molded coupons

The structure and morphology of syndiotactic polystyrene (sPS) injection molded coupons have been investigated using wide angle X-ray scattering (WAXS), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), light microscopy, and laser Raman spectroscopy (LRS). By sectioning the samples at approximately 200 mu m increments, profiles across ''hot molded'' (oil heated to 140 degrees C) and ''cold molded'' (water heated to 104 degrees C) coupons, could be built up. Using DSC and WAXS, variations in crystallinity and polymorphic phases were observed. The crystallinity was found to remain fairly constant in the ''hot molded'' samples, whereas the cold molded samples had a pronounced ''amorphous'' skin, before becoming more uniform towards the center of the specimen. Characterization of the polymers' microstructure, in the molded plaques, was achieved by optical birefringence. The surface of the plaques were successfully etched with an acid/permanganate solution, prior to SEM studies, to reveal their morphology. Overall, the coupons showed very little orientation effects and the structure appeared to be consistent with that of a semicrystalline polymer, crystallized under relaxed conditions.