Wave attenuation in particulate polymer composites: independent scattering/absorption analysis and comparison to measurements

Attenuation characteristics of ultrasonic longitudinal waves in particle-reinforced polymer-matrix composites are considered. The spatial decay of a plane wave in the composite is evaluated within the independent scattering/absorption theory valid for dilute particle concentrations, with the absorption loss in the viscoelastic matrix accounted for explicitly. Numerical analysis,is carried out for longitudinal wave attenuation in glass-particle reinforced epoxy composite and rubber-particle toughened poly(methyl methacrylate) (PMMA) blend. In the glass/epoxy composite, wave attenuation is due to absorption in the matrix and scattering by the particles, while in the rubber/PMMA blend, attenuation is additionally caused by absorption in the particles. The influence of matrix viscoelasticity on the low-frequency scattering characteristics of a particle is demonstrated, which show certain deviation from the classical Rayleigh scattering behavior. The frequency and particle-radius dependence of the scattering, absorption and the resulting attenuation characteristics are illustrated. Numerical results are discussed in comparison to existing experimental data of longitudinal wave attenuation in the two composites, and the predicting capability of the theory is found to be satisfactory. (C) 2002 Elsevier Science Ltd. All rights reserved.