MORPHOLOGY OF POLY(PHENYLENE SULFIDE) SINGLE-CRYSTALS GROWN BY A 2-STAGE SELF-SEEDING TECHNIQUE

We have successfully developed a two-stage self-seeding technique to grow poly(phenylene sulphide) (PPS) single crystals from dilute solution, and used these single crystals as model materials to investigate the morphological changes dependent upon the seeding and crystallization conditions. The seeding conditions control the coexistence of different crystal types and determine whether isolated single crystals will be grown. The crystal structure and morphology of PPS single crystals have been investigated by using the wide angle X-ray scattering (WAXS) and transmission electron microscopy techniques including surface decoration by polyethylene. The morphology of the PPS single crystals reveals a highly anisotropic needle-like habit with a very smooth fold surface and very rough growth edges. The aspect ratio of the PPS needle-like single crystals increases as the crystallization temperature and molecular weight increase. Formation of needle-like crystals, lack of sectorization, formation of macroscopically rough growth surfaces, and molecular weight and crystallization temperature dependency of crystal habit suggest a crystal growth model in which the PPS molecules fold parallel to the growth direction during the crystal growth stage from dilute solution.