STUDY OF THE STRUCTURAL RELAXATION OF POLYACRYLATES BY BRILLOUIN LIGHT SPECTROSCOPY

The structural relaxation of glass-forming polyacrylates has been studied by means of the Brillouin light scattering (BS) technique in the frequency range between 1 and 30 GHz. The specimens, consisting of transparent polyacrylate films supported by an opaque substrate, were analyzed by means of a high-contrast and high-resolution Fabry-Perot tandem interferometer. The entire set of relaxation parameters were obtained by the full spectrum analysis of BS data, at different temperatures. Analysis of BS measurements and their comparison with dielectric data taken on the same systems show that BS is sensitive to the alpha + beta relaxation at the highest temperatures and to the beta relaxation for temperatures approaching the glass transition temperature, T-g.