Epoxy resin/polyurethane functionally graded material prepared by microwave irradiation

The glass-transition temperature (Tg) and modulus (E) of graded material in a plastic–elastomer system prepared with layer-by-layer casting in connection with microwave curing were studied. Epoxy (EP) resin and polyurethane (PU) were selected as the plastic and elastomer components, respectively. The structure of the functionally graded material (FGM) was such that EP (E = 3.2 GPa, and Tg = 162°C) and PU (E = 0.069 GPa and Tg = −54°C) were both surfaces, with a stepwise gradient in EP and PU content existing between the two over a thickness of 9 mm. Fourier transform infrared spectroscopy and scanning electron microscopy were used to investigate the PU content and the morphologies of the FGMs separately. Finite element analysis (FEA) was used to simulate the temperature and thermal stress distribution along the graded direction under a steady-state, nonuniform temperature field. The results of FEA showed that the temperature and thermal stress distribution decreased along the graded direction. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 994–999, 2004