Thermal stabilities and mechanical interfacial properties of polyethersulfone-modified epoxy resin

In this study, the thermal stabilities and mechanical interfacial properties of a diglycidyl ether of bisphenol-A (DGEBA) epoxy resin modified with different contents of polyethersulfone (PES) were investigated. The curing behavior of the DGEBA/PES blends was characterized using differential scanning calorimetry (DSC). The thermal and interfacial properties of the blends were studied using thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and with a universal test machine (UTM). DSC revealed that the curing reaction rate decreased upon increasing the PES content. The TGA and DMA results indicated that the thermal stability and glass transition temperature (T _g) of the blends decreased slightly upon increasing the PES content. This phenomenon might be caused by a reduction in the crosslinking density of the epoxy network, which could be the result of incomplete curing of the epoxy functional groups in the DGEBA/PES blends. The fracture toughness factors (K_IC and G_IC) of the blends increased as the PES content increased. This finding indicates that the addition of PES into DGEBA increases the final toughness of the blends. The fractured surfaces were studied by SEM to investigate the morphology in the blends.