Department of Applied Physics II, University of Basque Country, Apdo. 644, 48080 Bilbao, Spain.
J Phys Chem B. 2010 May 27;114(20):6937-42. doi: 10.1021/jp910823c.
In this work, we have measured the thermodiffusion coefficient of different n-alkane binary mixtures at several concentrations using the thermogravitational technique. In particular, we have studied the n-dodecane/n-heptane system as a function of composition and other systems covering a large range of mass differences and concentration at 25 degrees C and 1 atm. The results show that for any concentration the thermodiffusion coefficient of n-alkane mixtures is proportional to the mass difference between the components and to the ratio of the thermal expansion coefficient and viscosity of the mixture. The obtained equation allows us to determine the infinite dilution values of the thermodiffusion coefficient. We compare these values with recent experimental results in dilute polymer solutions and analyze the Brenner theory of thermodiffusion. Finally, it is shown that the thermodiffusion coefficient depends linearly with the mass fraction, and it can be calculated from the viscosity and thermal expansion of the pure components.
在这项工作中，我们使用热重力技术测量了不同正构烷烃二元混合物在几个浓度下的热扩散系数。特别是，我们研究了正十二烷/正庚烷体系作为组成的函数，以及其他在 25 摄氏度和 1 大气压下涵盖质量差和浓度大范围的体系。结果表明，对于任何浓度，正构烷烃混合物的热扩散系数与组分之间的质量差成正比，与混合物的热膨胀系数和粘度之比成正比。所得到的方程允许我们确定热扩散系数的无限稀释值。我们将这些值与最近在稀聚合物溶液中的实验结果进行比较，并分析热扩散的 Brenner 理论。最后，表明热扩散系数与质量分数呈线性关系，可以从纯组分的粘度和热膨胀系数计算得出。
