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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，1,3-二苯基-1,1,3,3-四甲基二硅氧烷、欧米隆-三联苯、碳酸丙烯酯和邻苯二甲酸二丁酯的过冷液态中会发生β-玻璃化转变以及α-玻璃化转变。此外，在环己醇的塑性结晶状态下，存在两组α-和β-玻璃化转变以及发现发生另一组玻璃化转变。提出了液体中耦合的多种分子重排运动模式通过分子的位置排序而相互解耦的可能性。2)采用温度跳跃法对甘油、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的脆性各不相同。弛豫过程用拉伸指数函数的非指数参数 beta 来表征。研究发现，脆性 m 与弛豫函数对温度跳跃的非线性 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这种相关性的存在。3)通过温度跳跃法对芴-二苯并呋喃固溶体跟踪了类似的焓弛豫过程。对于每个化合物，非指数参数 beta 是恒定的，独立于 DELTA_jT。这一结果与过冷液体中的结果形成鲜明对比，表明液体中发现的非线性主要归因于平均弛豫时间的非阿伦尼乌斯性质。 4）在omicron-三联苯和salol各自的玻璃化转变区域中发现了由于均质晶胚/晶核聚集而产生的新结晶过程。发现生长速率是由β-弛豫率决定的，而不是由普遍认可的α-弛豫率决定的。