Effects of gamma-ray irradiation on a cyanate ester/epoxy resin

• A cyanate ester/epoxy resin was irradiated by γ-rays with dose of 100 MGy in vacuum.
• Viscoelastic property, structural change and gas evolution were investigated.
• Ether linkages in the network structure were mainly decomposed by the irradiation.
• The flexural strength of resin was maintained >170 MPa which is 90% of initial value.

Effects of γ-ray irradiation on a cyanate ester/epoxy resin composed of dicyanate ester of bisphenol A (DCBA) and diglycidyl ether of bisphenol A (DGEBA) were investigated by changes in physicochemical and mechanical properties after the γ-ray irradiation with dose of 100 MGy as maximum at around 40 °C under vacuum. After the irradiation, gases of hydrogen, carbon monoxide and carbon dioxide were evolved, glass transition temperature decreased, and flexural strength also decreased. It was concluded that ether linkages bonded to cyanurate, isocyanurate and oxazolidinone structures are mainly decomposed by the irradiation. After 100 MGy irradiation, the flexural strength of DCBA/DGEBA was maintained more than 170 MPa which is 90% of initial value of 195 MPa. Flexural modulus and density slightly increased to the values of 3.9 GPa and 1.211 g/cm3 from initial values of 3.4 GPa and 1.199 g/cm3, respectively.