Crystallization kinetics of J-1 polymer under different thermal treatments

Abstract

A bis-para-amino cyclohexylmethane (PACM)-based polyamide homopolymer (J-1 polymer produced by Du Pont), utilized as a matrix for composites, was subjected to different thermal treatments in order to investigate its crystallization thermodynamics and crystallization kinetics. Various J-1 samples, quenched, annealed from the glassy state, isothermally crystallized from the melt and slowly cooled, were studied by differential scanning calorimetry (DSC). A thermodynamic melting temperature of 352.6 °C was determined from a Hoffman-Weeks diagram of polymer samples annealed at different temperatures between the glass transition and melting temperature. By using DSC isothermal crystallization data from the melt, the existence of two crystallization regimes, already found in a previous investigation, was confirmed, and a transition temperature between the two regimes, equal to 262.2 °C was determined, in good agreement with 260.5 °C, obtained by depolarized light measurements, reported elsewhere. Moreover, the ratio between the crystallization kinetics factor of two crystallization regimes is 1.87, very close to the value of 2 predicted by the Huffman theory. Crystallization of samples from the melt, at different cooling rates, was also performed. The Arrhenius plot of data indicated that the crystallization process proceeds with two distinct activation energies (589 and 244 kJ mol−1), below or above a cooling rate of 2.67 °C min−1, corresponding to a temperature of 253.9 °C. This result is in good agreement with the two crystallization regimes reported above.