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Calorimetric Study on Structural Relaxation of Molecular Ground

分子基础结构弛豫的量热研究

基本信息

批准号：
06804032
负责人：
YAMAMURO Osamu
金额：
$ 1.34万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

A top-loating adiabatic calorimeter has been constructed for the first time. From the test experiments of an empty cell and benzoic acid (standard substance), the precision and accuracy of heat capacity were confirmed to be better that 0.1 % in the temperature region between 12 and 380 K.tri-OMICRON-methyl-beta-cyclodextrin (TMCD), sucrose (SUC), salicin (SAL), phenolphthalein (PP), 1,3,5-tri-alpha-naphthylbenzene (TNB), p-quaterphenyl (p-QP), p-terphenyl (p-TP) and 1,3,5-triphenylbenzene (TPB) were ground with a vibration mill and their abilities of mechanical milling amorphization were investigated by X-ray powder diffraction and differential thermal analysis. It was found that the ability of mechanical milling amorphization is strongly related to the glass forming ability.The heat capacities of the ground amorphous solids (GAS) and liquid-quenched glasses (LQG) of TMCD and TNB were measured with an adiabatic calorimeter in the temperature range between 5 and 380 K.It was found that GAS exhibits larger configurational enthalpy than LQG for both samples, suggesting that the molecular GAS has a structure with large orientational disorder, local strain, and defects.The grinding-time and grinding-temperature dependences of the enthalpy relaxation were investigated using TMCD.It was found that the amorphization process and enthalpy obtaining process are associated with not only the free-energy difference between the liquid and the crystal and the structural relaxation time but also the mechanical properties (e.g.plasticity) of the crystal and the amorphized solid.

首次构造了顶置式绝热量热计。通过空槽和苯甲酸（标准品）的测试实验，证实了在12 ~ 380 k的温度范围内，热容量的精密度和准确度在0.1%以内较好。用振动磨研磨对三苯基（p-TP）和1,3,5-三苯基苯（TPB），并用x射线粉末衍射和差热分析研究了它们的机械磨非晶化能力。结果表明，机械铣削非晶化能力与玻璃化能力密切相关。用绝热量热计在5 ~ 380 K范围内测量了TMCD和TNB的地面非晶固体（GAS）和液体淬火玻璃（LQG）的热容。结果表明，两种样品的GAS均表现出比LQG更大的构型焓，表明分子GAS具有较大的取向无序、局部应变和缺陷结构。利用TMCD研究了磨削时间和磨削温度对焓弛豫的影响。结果表明，非晶化过程和焓获得过程不仅与晶体与液体的自由能差和结构弛豫时间有关，还与晶体和非晶化固体的力学性能（如塑性）有关。