三乙酸甘油酯玻璃化转变的焓弛豫与介电弛豫研究

脆性较高的玻璃形成分子液体通常在焓弛豫和介电弛豫动力学上表现出明显的差异性, 为了深入理解这一问题, 本文针对具有较高液体脆性的三乙酸甘油酯对比研究了焓弛豫与介电弛豫行为. 利用这两个技术分别研究了结构弛豫动力学过程的非Arrhenius 与非指数特征, 液体脆性因子与非指数性因子的对比显示很好的一致性. 分析表明分子的柔性有可能对这两种弛豫过程中分子运动的相关性产生明显的影响. 讨论了玻璃形成液体的分子结构与动力学参数之间的关联.

Enthalpy and Dielectric Relaxations of Triacetin in the Vicinity of Glass Transition

To understand the experimental observation that the dynamic parameters determined for enthalpy and dielectric relaxation might differ in fragile glass-forming molecular liquids, a fragile molecular liquid, triacetin, was chosen for the study of the two relaxation dynamics. The non-Arrhenius and nonexponential characters were focused, and the kinetic fragility and non-exponential parameter determined from the two relaxation measurements were found to be remarkably similar. Experimental results indicate that the degree of correlation in the molecular motions involved in the two relaxations depends on molecular flexibility. The dependence of the dynamic parameters on molecular structures in the glass forming liquids is discussed.