Pressure dependence of viscosity of glassforming melts

We suggest a model in which the viscosity η is related to the entropy of the system. The model successfully describes the dependence of viscosity on pressure. A master equation is developed that allows a comparison of data obtained at different temperatures. Earlier, in the framework of the same model we described the dependence of viscosity on temperature. The present treatment gives a simple interpretation of Tg, the glass transition temperature, which takes places when the disorder in the amorphous system decreases to an extent that the dispersion σ is only 3.5% of maximum value of the activation energy Emax.