Isothermal and nonisothermal crystallization kinetics of partially melting nylon 10 12

Nylon 10 12, a newly industrialized engineering plastic, shows a double-melting phenomenon during melting. Partial melts were obtained when the sample was heated to the temperature between the two melting peaks. A differential scanning calorimeter was used to monitor the energies of the isothermal and nonisothermal crystallization from the partially melted samples. During isothermal crystallization, relative crystallinity develops with a time dependence described by the Avrami equation, with the exponent n = 1.0. For nonisothermal studies, kinetics treatments based on the Avrami and Ozawa equations are presented to describe the crystallization process. It was found that the two treatments can describe the nonisothermal crystallization from the partially melted samples. The derived Avrami and Ozawa exponents are all about 1.0, which means that the partially melted samples crystallize by one-dimensional growth, which may cause thickening of the lamellae. We calculated the crystallization activation energies for isothermal and nonisothermal crystallization from the partially melted samples. It was found that the activation energy determined by the Kissinger method was not rational, which may be attributed to the free-nucleation process for nonisothermal crystallization from partially melted samples. (C) 2003 Wiley Periodicals, Inc.