Study of polytetrafluoroethylene crystallization
Résumé
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) experiments, supported by scanning electron microscopy (SEM) observations. Isothermal crystallization of PTFE (between 315 °C and 325 °C) is analyzed and compared with PTFE cooled at 1 °C/min taken as the reference. We establish a TTC (time, temperature, crystallization) diagram and point out the time and temperature dependence of both crystallite thickness and crystallinity. It appears that the crystallization occurs in a very narrow temperature range. We assign the morphological changes to different crystal growth regimes in the range of study.