DIELECTRIC INVESTIGATIONS ON NOVOLAC PHENOL-FORMALDEHYDE RESIN

Permittivity epsilon' and dielectric loss epsilon'' of novolac have been determined in the temperature interval from -150 to 150-degrees-C and in the frequency interval from 10(2.5) to 10(6) Hz. Novolac exhibits a main and a secondary relaxation process. For the main relaxation a master curve of epsilon'' was calculated, the shape of which was described by the Havriliak-Negami function (HN). The parameters of the HN fit were interpreted by a model that relates the values to the polymer structure. Furthermore, the temperature dependence of the dielectric relaxation times was analyzed by a WLF approach for the main relaxation and an Arrhenius approach for the secondary relaxation. The dielectric relaxation times of the main relaxation were correlated with the electrical conductivity and the melt viscosity.