Investigations on the morphologies and properties of epoxy/acrylic rubber/nanoclay nanocomposites for adhesive films

The epoxy/acrylic rubber (ACM)/montmorillonite (MMT) nanocomposites have been prepared by simple solvent blending. The morphologies, storage modulus, glass transition temperatures, and physical properties have been investigated systematically. The decreased sizes and increased numbers of the epoxy domains in the epoxy/ACM blends were observed with the incorporation of MMT. The crosslinked epoxy/ACM binary blends show partially miscible phase structure, while the epoxy/ACM/MMT nanocomposites exhibit a more complete phase-separated behavior and an increased Tg of epoxy phase. It was found that the catalytic effect of MMT on the crosslinking reaction of epoxy resin accounts for the more complete separation of the two phases. A novel crosslinking induced clay exfoliation has been observed for the ternary nanocomposites. More surprisingly, a synergistic effect of MMT on both toughness and tensile modulus of epoxy/ACM blend were observed, probably originated from the fine domain sizes and appropriate interface-dispersed MMT platelets in the ternary nanocomposites. The fabricated materials have been used as the adhesive films for polyimide films and copper foils. The adhesive strength of the binary epoxy/ACM blends was found to be dependent on the thickness of the adhesive films. Moreover, a preferable increment in the adhesive property of epoxy/ACM/3 wt% MMT adhesive film was observed, resulting from the synergistic effect of the fine degree of crosslinking and tearing fracture of the adhesive film.