Regensburg 2019 – wissenschaftliches Programm
CPP 25.1: Poster
Dienstag, 2. April 2019, 14:00–16:00, Poster B1
Thermodiffusion of Binary Halobenzene-n-Alkane Mixtures — •Bastian Pur, Florian Schock, and Werner Köhler — Universität Bayreuth, 95440 Bayreuth, Germany
The Soret effect (thermophoresis) describes a diffusion flux that is driven by a temperature gradient in a multicomponent mixture. For dilute solutions of polymers with large Kuhn segments there is a remarkable universality for the thermophoretic velocity: it depends only on the viscosity η of the solvent. The thermal diffusion coefficient DT, also known as the thermophoretic mobility, multiplied by the solvent viscosity leads to a constant value (η DT ≈ const.). This universality is asymptotically also found for binary mixtures of methylnaphtalene and toluene in n-alkanes. To pursue these observations we have conducted measurements with halobenzene-n-alkane mixtures. The measured mixtures correspond to the series of halobenzenes fluoro-, chloro- and bromobenze mixed with n-alkanes nCi (i=6,7,8,10,12,14 and 16). By means of a holographic grating technique we have obtained the Fickian diffusion coefficient D, the Soret coefficient ST and the thermal diffusion coefficient DT. These results will be compared to the universal asymptotic limit of η DT reported for polymer solutions.