Non-isothermal curing kinetics and creep behavior of Al₂O₃/epoxy composites for extra-high vlotage gas insulated switchgear

Non-isothermal differential scanning calorimetry(DSC) method was used to study the curing behavior of Al₂O₃/epoxy (EP) composites for extra-high voltage gas insulated switchgear (GIS). The DSC curves were subjected to peak separation treatment, and the apparent activation energy of different reaction stages was studied by the equal conversion rate method. According to the Málek criterion, the model type of the curing behavior of Al₂O₃/EP composites was obtained, and the kinetic parameters of different reaction stages and the curing kinetic equation of the Al₂O₃/EP composites were obtained. The microstructure of Al₂O₃/EP composites was observed by SEM, dynamic thermomechanical properties and creep behavior of Al₂O₃/EP composites were analyzed by dynamic mechanical analysis(DMA), and the long-term creep properties were predicted by time-temperature superposition. The results indicate that DSC heat flow curves are bimodal of Al₂O₃/EP composites. The apparent activation energies of Al₂O₃/EP composites at two reaction stages are 35.3 kJ/mol and 48.1 kJ/mol, respectively. The curing behavior of Al₂O₃/EP composite system at different curing stages can be well described by the Sestak-Berggren model. Al₂O₃ particles are uniformly dispersed in the resin matrix, and the addition of Al₂O₃ filler causes cracks to be deflected. The storage modulus (E') of Al₂O₃/EP composites decreases with increasing temperature, and the peak of loss tangent (tanδ) corresponds to the glass transition temperature (T_g) is 120.03℃. Creep resistance of Al₂O₃/EP composites decreases with increase of tensile stress and temperature. The creep rate decreases over time.