Description of the Fragile Behavior of Glass Forming Liquids with the Use of Experimentally Accessible Parameters (Preprint)
Abstract
The three-fitting-parameter viscosity equations, i.e. Vogel-Fulcher-Tamman (VFT) and Avramov's equations, which are used to describe the temperature dependence of viscosity are modified into one-fitting parameter equations. Both modified equations contain the glass transition temperature Tg and fragility index m as material constants, allowing a direct comparison of the modified equations. Base on analysis of 12 glass-forming liquids, it is concluded that the modified Avramov's equation describes the experimental data slightly better than the modified VFT equation. Experimental data must be collected over a wide temperature range before the three-fitting-parameters of the VFT and Avramov equations can be determined and the equations can be applies. However, the modified equations developed here provide a convenient method of estimating the temperature dependence of viscosity by using the experimentally accessible parameters Tg and m, which can be determined by differential scanning calorimetry measurements conducted in a narrow temperature range near the glass transition temperature.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2009
- Accession Number
- ADA502788
Entities
People
- Daniel B. Miracle
- Oleg N. Senkov
Organizations
- Universal Energy Systems