To help recover the intrinsically valuable, reusable metal parts at the end of a product's life-cycle, we have used thermosetting (epoxy) resin that contains a small amount of thermoplastic polymer, polyethersulfone, which can be readily chemically decomposed. In a morphologically homogeneous modified thermosetting resin, the resin portion does not readily decompose when treated with an organic solvent, and chemical resistance equals the unmodified epoxy resin. A resin portion with thermoplastic polymer having continuous-phase morphology was finely broken down by treatment with an organic solvent, and the embedded metal parts were separated and recovered. Readily decomposed thermosetting resin can thus be obtained by controlling the morphology of the thermoplastic polymer in the thermosetting resin to form a continuous phase. We also obtained a material having continuous variation in the phase morphology of a cured resin, from that with homogeneous morphology to that with continuous-phase morphology of the thermoplastic polymer: phase structure inclination material. We were thus able to control the decomposition rate by chemical treatment in one resin. (c) 2006 Wiley Periodicals, Inc.