Raman scattering in amorphous and crystalline materials: a study of epoxy resin and DGEBA

Abstract

Raman scattering has been measured in amorphous and crystalline diglycidyl ether of bisphenol A (DGEBA) and in epoxy resins made from DGEBA hardened with ethylene diamine. The spectra of the amorphous materials show a constant frequency dependence beyond a certain crossover frequency which depends on the characteristic molecular length. These results are compared with similar data obtained from inelastic neutron scattering and good agreement with the phonon-fraction hypothesis of Alexander and Orbach (1982) is obtained. The results yield a fracton dimensionality of 4/3 if the superlocalisation exponent d_phi is taken to be equal to the resistivity exponent zeta . In the crystalline DGEBA, characteristic peaks in the Raman spectrum compare well with those obtained by inelastic neutron scattering.