Morphology-enhanced properties of an interpenetrating polymer network adhesive

An interpenetrating polymer network (IPN) adhesive was produced from electron beam cured acrylate and thermally cured epoxy components. The acrylate component was 80% bisphenol A epoxy diacrylate and 20% trimethylolpropane triacrylate. The epoxy component was a flexible mixture of 50% diglycidyl ether of bisphenol A (DGEBA) and 50% poly(propylene glycol) diglycidyl ether cured with 2-ethyl, 4-methyl imidazole. Bulk properties of an approximately 50/50 acrylate/epoxy IPN adhesive were tested and compared to those of its individual components. Mechanical tests show that the IPN possesses a favorable combination of acrylate strength and modulus plus epoxy flexibility, and the IPN fracture toughness is more than double the value of its individual components. These improvements are attributed to the IPN morphology as revealed by scanning electron microscopy.