Cure Kinetics of Epoxy-Novolac Resin Containing Tetrabromo-bisphenol-A as a Flame Retardant by Isothermal Calorimetry Method

Cure kinetics of an epoxy-novolac resin with tetrabromo-bisphenol-A، as a flame retardant، was investigated in the presence of nadic methyl anhydride as a curing agent. Different amounts of benzyl dimethyl amine were used as accelerator. The studies on kinetics were carried out using isothermal DSC experiments at 100، 110، 120 and 130°C. The conversions were calculated based on the total heat of curing reaction obtained from non-isothermal DSC analysis at a heating rate of10°C/min. Kinetic parameters were obtained from isothermal analysis and by a model especifically for autocatalytic curing reactions which have been developed by Kamal and Sourour. The results obtained illustrate that the reaction is controlled by kinetic and diffusion parameters at different reaction stages. In other words، before a glassy state is reached the reaction mainly proceeds with autocatalytic behavior and can be well explained by the equation containing k1 and k2 as the rate constants and n and m as the reaction orders. At higher conversion levels، at about 65%، at the onset of network formation the system turns to a glassy state، the curing reaction is mainly controlled by diffusion (diffusion-controlled system). We conclude therefore that، theoretical and experimental data would be confirmed by considering the diffusion parameters in the corresponding model.