Abstract
Phase structures, damping properties and adhesive properties of carboxyl-terminated butadiene acrylonitrile rubber (CTBN) /epoxy polymer blends were evaluated in relation to the pre-reaction time between CTBN (60wt%) and diglycidyl ether of bisphenol-A (DGEBA). When the pre-reaction of CTBN/DGEBA was insufficient, the blend resin showed micro-phase separation with rubber-rich continuous phase including epoxy-rich dispersed phases. The composite loss factor （η） for a steel laminate, which consisted of two steel plates with the CTBN/epoxy alloy resin layer in between, highly depended on the environmental temperature and the resonant frequencies. On the other hand, as the pre-reaction of CTBN/DGEBA proceeded, the compatibility among components was enhanced and the phase size became small up to nano-scale. Also, the compatibilized CTBN/DGEBA cured resin had broad glass transition temperature range, and resulted in the high loss factor for the steel laminate in broad temperature range as well as at several resonant frequencies. The internal nano-structures with versatile relaxation mechanisms of the compatibilized CTBN/DGEBA resin would be the source of the viscoelastic behaviors and high damping properties. Both shear adhesive strength and peel adhesive strength of the resin to aluminum substrates were also increased with the progress of the pre-reaction of CTBN/DGEBA. Rubber-rich continuous phase with epoxy and curing agent made the cross-linked structures together. This accounted for high modulus, high strength and high fracture energy of the pre-reacted CTBN/DGEBA bulk resin, led to the high adhesive strengths.
