Ratio of dielectric strength of structural and secondary relaxation close to the glass transition for PPGE and DGEBA

Abstract

Here, dielectric spectroscopy is used in the fre- quency range from 10 -2 Hz up to 10 7 Hz and we found dynamics of the primary α-and intermolecular Johari–Goldstein β-processes are strongly correlated in diglycidyl-ether of bis-phenol-A and poly phenyl glycidyl-ether (PPGE) over a wide temperature from 193 to 345 K and pressure P range from 0.1 to 600 MPa. In contrast with the widespread opinion of statistical independence of these processes the α-β mutual dependence is quantitatively confirmed in [1] analysing the temperature and pressure behavior of the α-and (JG) β-processes the investigation of the ratio of dielectric strength of two processes close to T g evidence that the importance of secondary dy namics in relaxing external electric stresses increase in glass formers at high pressures with respect to that of the structural relaxation. We suggest that the thermal agitation, acting above T g is at the basis of the observed result.