BRILLOUIN-SCATTERING AND ULTRASONIC STUDY ON AN EPOXY PREPOLYMER

The temperature dependence of elastic properties in a common epoxy pre polymer was investigated using Brillouin scattering and ultrasonic pul se spectroscopy. In the GHz region, the Brillouin shift frequency curv e showed a sharp kink at about 250 K; which was in good accordance wit h T-g observed by DSC. The D-90R function calculated from the Brilloui n shift frequency showed a clear dispersion at temperatures near 350 K , at which a broad peak of the Brillouin linewidth was observed. In th e MHz region, ultrasonic wave attenuation also showed a peak near 285 K. Assuming that these changes result from the a relaxation in the gla ss transition region, the frequency-temperature behavior of the peaks was discussed in connection with the a relaxation in fully cured epoxy resin.