Nonisothermal crystallization kinetics of polytetrafluoroethylene

An analysis of the crystallization kinetics of polytetrafluoroethylene (PTFE) under nonisothermal conditions is presented. A simple method is proposed to remove the limits of the Ozawa theory. The Avramic exponent, n, can be reasonably well determined from the nonisothermal crystallization exotherm. An n value of ∼1.49 was obtained for PTFE, which indicates the formation of one‐dimensional crystallites (fibrillar type) after thermal nucleation or two‐dimensional crystallites (discs) after athermal nucleation. Both these morphologies were experimentally observed. For PTFE crystallization from the melt, activation energy was obtained as 34 kcal/mol. This is much smaller than those of PEEK and PET, indicating a very fast crystallization of PTFE.