PTFE crystallization mechanisms: Insight from calorimetric and dilatometric experiments

Abstract

PTFE presents an original secondary crystallization that appears to be independent of the primary one.The conjunction of differential scanning calorimetry and dilatometry experiments has offered complementarydata to study both crystallization melted compacted powder and of recrystallized samples. The primarycrystallization is responsible for the crystallinity content variation with the cooling rate. It preserves theanisotropy induced by previous compaction that can be observed by dilatometry. Conversely, the secondarycrystallization appears to be instantaneous, reversible, kinetic-free and isotropic. It occurs over a widetemperature range between 250◦C and 310◦C.