The α‐relaxation process of seven commercial diglycidyl ether of bisphenol‐A (DGEBA) epoxy resins of varying molecular weights, without hardener, was characterized by measuring the frequency and temperature dependence of the complex permittivity, (ϵast;). The temperature dependences of the frequency of maximum dipole loss ƒ max and the ionic conductivity σ are non‐Arrhenius and can be described by the Williams‐Landel‐Ferry (WLF) equation. The frequency dependence of the molecular relaxation process is described by the Kohlrausch‐Williams‐Watts (KWW) relaxation function. The WLF C 1 parameter and the KWW β parameter, describing the temperature and frequency dependences, respectively, vary systematically with the molecular weight of the resin. These results are discussed in the context of recent theories of the glass transition.
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Sheppard et al. (1989) studied this question.
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