Brillouin scattering study on the elastic properties of epoxy adhesive layer

Wave properties (wave velocity and attenuation) in epoxy adhesive layers du ring cure were investigated. Longitudinal and shear wave properties in the GHz region were measured by the Brillouin scattering technique using 90 deg rees A-scattering geometry. The longitudinal and shear wave properties show ed similar changes during cure. Compared with the ultrasonic wave propertie s in the MHz region, a clear frequency dispersion could be seen during cure , in the glass transition region. It is supposed that this dispersion resul ts from a strong alpha relaxation. Longitudinal modulus and shear modulus w ere also obtained from the longitudinal and shear wave velocities. The long itudinal modulus was always proportional to the shear modulus during the en tire curing process.