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Search for Elementary Rearrangement Process and Investigation of Irreversible Structural Relaxation in Simple-Molecular Liquids

简单分子液体中基本重排过程的搜索和不可逆结构弛豫的研究

基本信息

批准号：
06453017
负责人：
OGUNI Masaharu
金额：
$ 4.74万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
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

1) beta-glass transition as well as alpha-one were found by an adiabatic calorimetry to occur in the supercooled liquid state of 1,3-diphenyl-1,1,3,3-tetramethyldisiloxane, omicron-terphenyl, propene carbonate and dibutylphthalate. Further, in the plastically crystalline state of cyclohexanol, there were two sets of alpha-and beta-glass transitions and another glass transition found to occur. A possibility was suggested that plural modes of molecular rearrangement motions coupled in liquid were decoupled from each other through the positional ordering of molecules.2) alpha-relaxation processes under constant temperature condition were studied calorimetrically by the temperature jump method for glycerol, propylene glycol, 1,3-diphenyl-1,1,3,3-tetramethyldisiloxane and dibutylphthalate with different fragilities from each other. The relaxation processes were characterized in terms of the nonexponentiality parameter beta of stretched exponential function. A strong correlation was found to exist between the fragility m and the nonlinearity delta=dbeta/dDELTA_jT of relaxation function to the temperature jump. The presence of the correlation was also confirmed by a computer simulation of the ireversible relaxation process based on a thermal activation model.3) The similar enthalpy relaxation processes were tracked by the temperature jump method for fluorene-dibenzofuran solid solutions. The nonexponentiality parameter beta was constant independently of DELTA_jT for each conpound. This result is quite in contrast to that in supercooled liquid, demonstrating that the nonlinearity found in liquid is attributed mainly to a non-Arrhenius property of the average relaxation times.4) A new crystallization process due to the aggregation of homogeneous crystal embryos/nuclei was discovered in omicron-terphenyl and salol in their respective glass transition regions. The growth rate was found to be determined by the beta-relaxation rate but not by the alpha-one commonly recognized.

1)通过绝热量热法发现在1，3-二苯基-1，1，3，3-四甲基二硅氧烷、三联苯、碳酸丙烯酯和邻苯二甲酸二丁酯的过冷液态中发生β-玻璃化转变以及α-酮。此外，在环己醇的塑性结晶状态下，存在两组α-和β-玻璃化转变，并且发现发生另一种玻璃化转变。2）采用温度跃变法对不同脆性的甘油、丙二醇、1，3-二苯基-1，1，3，3-四甲基二硅氧烷和邻苯二甲酸二丁酯在恒温条件下的α弛豫过程进行了量热研究。用拉伸指数函数的非指数性参数β表征弛豫过程。发现脆性m与弛豫函数对温度跃变的非线性度delta=dbeta/dDELTA_jT之间存在很强的相关性。基于热活化模型的不可逆弛豫过程的计算机模拟也证实了相关性的存在。3）采用温度跃变方法跟踪了芴-二苯并呋喃固溶体的类似焓弛豫过程。非指数性参数β是恒定的，独立于每个复合物的DELTA_jT。这一结果与在过冷液体中的结果形成鲜明对比，表明在液体中发现的非线性主要归因于平均弛豫时间的非阿耳忒修斯性质。4）在三联苯和salol的玻璃化转变区发现了一个新的结晶过程，这是由于同质晶胚/晶核的聚集。发现生长速率由β-松弛速率决定，而不是由通常公认的α-松弛速率决定。