A composition includes an epoxy-based curable adhesive having at least one an epoxy resin modified acrylonitrile-butadiene copolymer and at least one thermoplastic elastomer. The at least one thermoplastic elastomer is present in the curable adhesive as a penetrating polymer network. Further, an expandable article is composed of the composition, a reinforcing element includes a support and an expandable article, a method for reinforces cavities of structural components, and the composition is used as a shape memory material.