Physical and mechanical interfacial properties of epoxy copolymers initiated by latent thermal catalysts

The epoxy copolymers containing sulfone groups, diglycidyl ether of bisphenol-A - Bisphenol-S (DGEBA-S) were synthesized by a hot-melt method. The thermal properties of the epoxy systems initiated by two cationic latent catalysts, i.e., N-benzylpyrazinium hexafluoroantimonate (BPH) and N-benzylquinoxalinium hexafluoroantimonate (BQH), were investigated by using a dynamic DSC, DMA, and TGA. The mechanical properties were measured by single-edge-notched (SEN) beam fracture toughness tests. As a result, the thermal stability and mechanical interfacial properties of the DGEBA-S/catalyst system were found to be higher than those of the DGEBA/catalyst. This was probably due to the fact that the introduction of sulfone groups with a polar nature to the main chain of the epoxy resins led to an improvement of thermal stability and toughness of the cured epoxy copolymers.