Abstract

A gamma relaxation dielectric loss peak has been measured in the temperature range 113 -163 K for a series of
epoxy resins based on diglycidyl ether bisphenol-A (DGEBA). The network architecture of the examined systems
were systematically altered using varied types of functional network modifiers featuring different functional
groups. Analysis of the temperature dependence of the loss peak frequency leads to a radically new interpretation
of the fundamental processes that are associated with the gamma relaxation. The analysis has shown that the relaxation process can best be described in terms of a thermally assisted tunnelling displacement of a proton, termed activated tunnelling. The parameters derived not only fit the experimental data well, but have a clear physical origin that is
shown to be consistent with the network topology as expressed through the glass transition temperature. The
maximum temperature for which such behavior is observable has been determined and shown to be consistent
with the measurements. The approach proposed here provides a new method for understanding  relaxations in
these and similar systems.