Brillouin scattering and ultrasonic study on an epoxy prepolymer

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