Adhesive Characteristics of Epoxy/Dendritic Hyperbranched Polymer Blends

Adhesive characteristics of blends of a room-temperature-curing epoxy and a dendritic hyperbranched polymer (HBP) were investigated. Significant improvements in both lap shear and T-peel strengths were observed as a result of blending of HBP. Dynamic mechanical analysis of the cured blend formulations indicates a two-phase microstructure. The improvement in adhesive bond strength is achieved without significant sacrifice in glass-transition temperature of the cured epoxy network. The results were explained in terms of phase morphology analyzed by scanning electron microscopy. Cavitation and shear yielding are believed to be responsible for improvement in toughness and adhesive bond strength.