Estudo da cinética de cura de um pré-impregnado de resina epoxídica/fibra de carbono pelo método isoconversional

Abstract

This paper aims to determine the kinetics of a pre-impregnated ("prepreg") epoxy resin/carbon fiber using differential scanning calorimetry (DSC) with the isoconversional method. The latter method analyzes the cure kinetics through the dependence of activation energy during conversion (isothermal analysis) or temperature (non- isothermal analysis) and uses this dependence to calculate the kinetic parameters. The evaluation of reaction kinetics by DSC is based on the heat generating rate during an exothermic reaction. The hypothesis that a heat generated by a chemical reaction is proportional to the extension of cure allows one to obtain the kinetic parameters from the DSC curves obtained with the isothermal and nonisothermal modes. For the isoconversional isothermal method, the average activation energy ranged between 72 and 103 kJ/mol while in the non-isothermal method an average value of 80.5 kJ/mol was obtained. These results were compared with those obtained for ASTM E 2070 and ASTM E 698 methods, whose values were 89±5 kJ/mol and 77.5±2.5 kJ/mol, respectively, proving the efficiency of the method.