Dispersion of Acoustic Waves By an Alumina-Epoxy Mixture

Abstract

A differential-path ultrasonic technique is used to obtain the acoustic wave propagation characteristics of a mixture of alumina (Al₂O₃) particles and epoxy (Epon 828-Z). Longitudinal and shear acoustic data are ob tained over a frequency range of 0.5 to 2 MHz and a temperature range of —61°C to 75°C. The longitudinal, shear, and Poisson's ratio master-curve material functions are derived from these data using techniques that were developed for homogeneous isotropic polymers. These functions constitute a complete material description for the mixture in the time (frequency) and temperature range where viscoelastic dispersion is the dominant disper sion mechanism in the composite.