Journal of Applied Polymer Science, Vol.86, No.3, 589-595, 2002
Polymerization mechanisms and curing kinetics of novel polumercaptan curing system containing epoxy/nitrogen
The bis[3-(2,3-epoxypropylthio)phenyl]-sulfone (BEPTPhS)/trimercaptothioethylamine (TMTEA) system has a self-catalytic effect and can cure without any other accelerator. The curing kinetics of the BEPTPhS/TMTEA system was studied by means of the dynamic and isothermal differential scanning calorimetry method. The dynamic kinetic parameters were calculated with the aid of the Kissinger and Ozawa methods. The kinetic reaction mechanism in the isothermal reaction of BEPTPhS/TMTEA was shown to follow autocatalytic kinetics. The isothermal kinetic parameters, including k(1), k(2), m, and n, from the model proposed by Kamal were determined by fitting the experimental data; a good description of the curing kinetics was obtained, although deviations were observed at low conversions. The Arrhenius kinetic analysis indicated that the activation energy decreased with the increase of the reaction conversion, which indicated a change of the reaction mechanism. The isothermal kinetic analysis and Arrhenius kinetic analysis both demonstrated that the catalytic effect of the nitrogen atom in TMTEA predominated at low conversions and the autocatalytic effect predominated at high conversions.