A cure kinetics, diffusion controlled and temperature dependent, identification of the Araldite LY556 epoxy

The curing of the LY556 epoxy system, a DGEBA-type epoxy resin with an anhydride hardener HY917 and a l-methyl imidazole DY 070 accelerator, mass ratio 100:90:2, was investigated by isothermal and nonisothermal differential scanning calorimetry (DSC). Dynamic measurements were used to evaluate the total, ultimate, heat of the epoxy resin thermosetting reaction and enable experimental conversion determination for isothermal curing. Aiming further finite element modelling of the curing, this article especially focuses on a complete, temperature dependent, cure kinetics parameters identification strategy with the Kamal and Sourour phenomenological model expanded by a diffusion factor. A special attention was given for diffusion description which allows the identification of a fixed order of reaction for the LY556 epoxy resin. Based on isothermal conversion data analysis, the methodology for cure kinetics parameters identification is presented. This led to a temperature dependent identification of all cure kinetics parameters of the LY556 epoxy blend, including diffusion control description and corresponding temperature dependency. Cure kinetics identification quality and importance of diffusion control phenomenon for the curing of the epoxy are then highlighted by computed conversion results that fit almost well the data in the range of temperature used for identification.