STUDY OF POLYTETRAFLUOROETHYLENE CRYSTALLIZATION

Crystallization of polytetrafluoroethylene (PTFE) from the melt state has been studied by wide angle X-ray scattering (WAXS), small angle X- ray scattering (SAXS) and differential scanning calorimetry (DSC) expe riments, supported by scanning electron microscopy (SEM) observations. Isothermal crystallization of PTFE (between 315 degrees C and 325 deg rees C) is analyzed and compared with PTFE cooled at 1 degrees C/min t aken as the reference. We establish a TTC (time, temperature, crystall ization) diagram and point out the time and temperature dependence of both crystallite thickness acid crystallinity. It appears that the cry stallization occurs in a very narrow temperature range. We assign the morphological changes to different crystal growth regimes in the range of study.