EFFECT OF ACCELERATED AGING ON THE DIELECTRIC BEHAVIOR OF SOME VARNISH DRY FILMS

The variation of the dielectric constant epsilon', and the dielectric loss epsilon'' of polyesteramide, alkyd polyesteramide and alkyd varni sh dry films were measured within the frequency range from 10(5) to 10 (7) Hz and the temperature range from 20 to 50 degrees C. The varnish films were subjected to accelerated ageing by heating at 110 degrees C for different durations. The effect of the accelerated ageing on epsi lon' and epsilon'' were measured. The activation energy and the entrop y change of dielectric relaxation for the dry films before and after a geing were also calculated. All the results obtained were recorded and discussed in correlation with the molecular structure of the investig ated varnishes.