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

1)绝热量热法发现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在过冷液相中发生了β-玻璃化转变和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，并发现发生了另一种玻璃化转变。2)用温跃法研究了不同脆性的甘油、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松弛过程。用拉伸指数函数的非指数参数β刻画了松弛过程。脆性m与松弛函数对温度跃变的非线性函数Delta=dbeta/dDELTA_JT之间存在很强的相关性。基于热激活模型的不可逆弛豫过程的计算机模拟也证实了这种关联性的存在。3)用温度跳跃方法跟踪了荧二苯并呋喃固溶体的类似的热焓松弛过程。对于每个复合体，非指数参数β是独立于Delta_JT的常量。这一结果与过冷液体中的结果完全相反，表明液体中的非线性主要归因于平均弛豫时间的非阿累尼乌斯性质。4)在奥米克龙-三联苯和沙洛尔的玻璃化转变区发现了由于均匀晶胚/晶核聚集而导致的新的晶化过程。增长率被发现是由β-松弛速率决定的，而不是由公认的阿尔法-1决定的。

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.