Dismantlement behavior and strength of dismantlable adhesive including thermally expansive particles

This paper presents a quite new technique to realize dismantlable joints bonded with adhesive including thermally expansive particles. The thermally expansive particles are a kind of microcapsule consisting of plastic shells filled with liquid hydrocarbon which can expand by adding heat. The volume of the adhesive, including the particles, can also increase due to the expansion of the particles even though the resin of the adhesive has been fully cured, causing the fractures of joints bonded with the adhesive. Since the total expansion of the adhesive depended on the content of the particles, we measured the expansion changing the content of the particles and the temperature. Experiments on joints bonded with the adhesives, which had the different weight fractions of the particles, were carried out in order to immerse them in boiling water or to keep them in hot air. Cracks were generated and then propagated mainly on the interfaces between the adhesive and the adherends of the joints due to internal stress. The joints bonded with the adhesive which included 30 wt% of the particles showed fairly good bond strength and they could be dismantled perfectly in the experiments. (C) 2003 Elsevier Ltd. All rights reserved.