Hypersonic absorption in amorphous polymers by light scattering

Abstract

Brillouin lines have been observed in the spectrum of light scattered by poly(methylmethacrylate) and, for the first time, for poly(vinylchloride). The line widths have been measured, by a special technique, as a function of temperature. The attenuation per wavelength of thermal phonons below the glass transition temperature is almost constant over a wide frequency range (5 MHz to 10 GHz). The attentuation is ascribed to the mechanical strain field round static imperfections. Above the glass transition temperature the attenuation is associated with the well-known mechanical ∝ process. The Rayleigh light scattered by these polymers and their transparency is also discussed.