Pragmatical access to the viscous flow of undercooled liquids

The paper derives a relation for the viscosity of undercooled liquids on the basis of the pragmatical model concept of Eshelby relaxations with a finite lifetime. From accurate shear relaxation data in the literature, one finds that slightly less than half of the internal stresses relax directly via single Eshelby relaxations; the larger part dissolves at the terminal lifetime, which is a combined effect of many Eshelby relaxations.

Figure 1

Fit of recoverable compliance data [1, 2] in terms of the pragmatical model.

Figure 2

Fit of (a) $G\left(\omega \right)$ data and (b) dielectric relaxation data of propylene carbonate [9] in terms of the pragmatical model.

Figure 3

Fit of (a) $G\left(\omega \right)$ data [8] and (b) dielectric relaxation data [20] of propylene glycol in terms of the pragmatical model.