Avramov I
Institute of Physical Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
Phys Rev E Stat Nonlin Soft Matter Phys. 2014 Mar;89(3):032301. doi: 10.1103/PhysRevE.89.032301. Epub 2014 Mar 3.
Two problems have intrigued experts for a long time: The one is within the context of the legend of flowing cathedral glass windows and the second is the inaccuracy appearing in very old thermometers of famous scientists. We relate this with the role of the surface on the apparent viscosity of glasses. The apparent viscosity could deviate from the bulk viscosity if the fraction w of the surface molecules, of small samples, is sufficiently large. The effect is more prominent at low temperatures, correspondingly at high viscosities. The interpretation is within the Avramov and Milchev viscosity model, combined with the predictions of the change of heat capacity for extremely small samples. We find that the apparent glass transition temperature could depend on the sample size, in agreement with experimental observations existing in the literature. In addition to glasses, the present results could be of importance for thin films and foams.
长期以来，有两个问题一直吸引着专家们：一是在流动的大教堂玻璃窗传说的背景下，另一个是著名科学家非常古老的温度计中出现的不准确性。我们将此与表面对玻璃表观粘度的作用联系起来。如果小样品表面分子的分数w足够大，表观粘度可能会偏离本体粘度。这种效应在低温下更明显，相应地在高粘度下也更明显。这种解释基于阿夫拉莫夫和米尔切夫粘度模型，并结合了极小小样品热容变化的预测。我们发现，表观玻璃化转变温度可能取决于样品大小，这与文献中现有的实验观察结果一致。除了玻璃，目前的结果对于薄膜和泡沫也可能具有重要意义。
