Dielectric behaviour versus temperature of a monoepoxide

The conductivity;and dielectric relaxation behaviour of a:glass-forming monoepoxide, cresyl glycidyl ether (CGE), were studied from 10(2) to 10(7) Hz by impedance spectroscopy, in the temperature interval 83-333 K. Data analysis indicated the existence of a transition temperature T-B congruent to 265 K marking the separation between two different relaxation regimes, in accordance with previous results given by Stickel and co-workers. The temperature T-B is well above the glass transition temperature (T-g = 204 K), and coincides with the temperature at which the timescales of the main and secondary relaxation processes coincide, so at T > T-B there is a unique overall relaxation process. The splining layout of CGE differs from that of the very common diepoxide diglycidyl ether of bisphenol-A (DGEBA), studied previously, and also the relaxation at high temperature has a correspondingly different dynamical behaviour. The relaxation strength behaviour is also analysed and compared with that of DGEBA; the similarities are discussed.