Activation energies derived from the pre-glass transition annealing peaks

The paper explores the use of the DSC annealing peaks for estimating the activation energies of the beta-relaxation in low and high molecular glassy systems. For the four studied systems that include D-glucose (dextrose), maltitol, poly(methyl methacrylate) and poly(ethylene terephthalate) the estimated values of the activation energy are 59 +/- 10, 71 +/- 6, 73 +/- 12 and 75 +/- 7 kJ mol(-1). These values together with the activation energies determined earlier from the annealing peaks of polystyrene (PS), PS-clay nanocomposite, indomethacin, ursodeoxycholic acid and poly(vinylpyrrolidone) have been compared against the literature values of the activation energies of the beta-relaxation. It is concluded that the DSC estimates typically do not deviate for more than 20% from the reference values obtained by the standard dielectric and mechanical methods. (c) 2006 Elsevier B.V. All rights reserved.