Viscosity-temperature Relation of Aggregation Energies in Glass Forming Process

Abstract

Based on the dynamics of vitrification process driven by the configurational entropy, a novel expression of viscosity- temperature relation with the form of Fermi-type function is deduced below melting temperature by supposed an exponential function of average aggregation energy with temperature. The ‘molecular rearrangement’ to form aggregated regions at temperatures below the melting temperature is major contribution to the aggregation energies for describing vitrification process. The expression of relaxation time or viscosity is confirmed with several super-cooled liquids in broad temperature region. The expression contains the Vogel-Fulcher relation in limited temperature region and can avoid Kauzmenn paradox. The derived fragility shows that a reduced temperature may be a common structural variable in comparing various glassy liquids.