Radiation-induced degradation of an epoxy thermoset supported by hydrogen peroxide

• Mechanism of the radiation induced degradation of epoxy resin was proposed.
• Epoxy thermoset swelled with H2O2 is radiation susceptible.
• Radiation treatment followed by H2O2 swelling can be applied for resin recycling.

Epoxy resin was decomposed applying two complementary treatments, namely (1) soaking up with 30% aqueous solution of hydrogen peroxide and (2) exposure of the swelled material to ionizing radiation in air atmosphere over doses up to 1000 kGy. The phase transition characteristic determined by the DSC technique revealed that both factors, swelling with oxidizing agent and irradiation applied sequentially induce in the resin deep structural changes resulting in the rise of two new exothermic transitions assigned to hydrogen peroxide decomposition and resin oxidation. The flexural stress at break measurements confirmed significant influence of H2O2 on the mechanical properties of the irradiated material which, under applied conditions, is efficiently decayed via oxidative degradation. On the basis of results obtained by EPR spectroscopy chemical mechanism of the radiation induced degradation was proposed.