Characteristic relaxation times and their invariance to thermodynamic conditions
Characteristic relaxation times and their invariance to thermodynamic conditions
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DOI：
10.1039/b804794d
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发表时间：
2008-11
期刊：
影响因子：
3.4
通讯作者：
C. M. Roland
中科院分区：
文献类型：
--
作者：
C. M. Roland
分子液体和聚合物的动力学表现出各种“转变”，与特性的变化有关。随着温度的降低或压力的增加，这些转变包括（i）分子间协同性的开始，随之而来的非阿耳忒弥斯和非德拜行为;（ii）动态交叉，弛豫时间和强度的导数表现出断裂;（iii）玻璃化，对应于平移和旋转运动的停止;和（iv）对于各向异性分子，液晶性的发展。在液体的每一个转变中，结构或再取向弛豫时间是恒定的，与热力学条件无关;也就是说，虽然转变的温度取决于压力，但弛豫不依赖于压力。
The dynamics of molecular liquids and polymers exhibit various “transitions”, associated with characteristic changes in properties. With decreasing temperature or increasing pressure, these transitions include (i) the onset of intermolecular cooperativity with consequent non-Arrhenius and non-Debye behavior; (ii) the dynamic crossover at which derivatives of the relaxation time and strength exhibit breaks; (iii) vitrification, corresponding to cessation of translational and rotational motions; and (iv) for anisotropic molecules the development of liquid crystallinity. At each of these transitions of a liquid, the structural or reorientational relaxation time is constant, independent of thermodynamic conditions; that is, while the temperature of the transition depends on pressure, the relaxation does not.