Phenomenological relationship between dielectric relaxation and thermodynamic recovery processes near the glass transition
Phenomenological relationship between dielectric relaxation and thermodynamic recovery processes near the glass transition
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介电弛豫与玻璃化转变附近的热力学恢复过程之间的唯象关系
DOI：
10.1021/ma00154a048
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发表时间：
1985
期刊：
影响因子：
5.5
通讯作者：
T. Furukawa
中科院分区：
文献类型：
--
作者：
S. Matsuoka;G. Williams;G. Johnson;E. Anderson;T. Furukawa
将 Dirac 5 形式的非晶态聚醋酸乙烯酯超过 6 个十年的实验介电弛豫谱应用于热力学恢复过程的基本非线性微分方程，准确地再现了体积弛豫数据。众所周知，实验介电弛豫时间遵循 Vogel-Fulcher（或 WLF）方程。发现体积数据的热力学恢复时间精确等于 Tg 附近的介电弛豫时间，但在较低温度下与介电数据的外推法不同。恢复时间将取决于活性温度，遵循相同的沃格尔公式而不是纳拉亚纳斯瓦米公式，但其温度依赖性遵循阿伦尼乌斯公式。弛豫时间随老化的变化是根据由此评估的方程计算出来的，并且与粘弹性和介电数据一致，清楚地表明该弛豫时间不应与从热力学恢复总体速率获得的“有效”r 混淆。这些现象对于聚合物和非聚合物来说很常见，因为聚醋酸乙烯酯和葡萄糖都被发现表现出对所研究的行为至关重要的所有物理性质。玻璃形成液体中缓慢弛豫过程的物理学仍然引起许多工作者的兴趣。对热力学恢复过程的现象学理解取得了实质性进展，这尤其要归功于 Moynihan 及其同事 1-3 以及 Kovacs 及其同事 4、5 的工作，通过引入叠加在弛豫时间对结构变化的非线性依赖性上的弛豫时间分布。它们的基本微分方程本质上是相同的具有分布阶参数的非线性方程。 Moynihan（M 模型）调用 Kohlrausch-Williams-Watts 松弛函数，6 而
Applying the experimental dielectric relaxation spectrum of amorphous poly (vinyl acetate) in the form of Dirac 5’s over 6 decades of time to the basic nonlinear differential equation for the thermodynamic recovery process accurately reproduced volume relaxation data. Experimental dielectric relaxation time follows the Vogel-Fulcher (or WLF) equation, as is well-known. The thermodynamic recovery time from volume data5 was found to be precisely equal to the dielectric relaxation time near Tg but at lower temperatures to diverge from the extrapolation of the dielectric data. The recovery time will depend on the Active temperature following the same Vogel formula rather than Narayanaswamy’s formula, but its temperaturedependence follows the Arrhenius formula. The shift ofthe relaxation timewith aging was calculated from the equations thus evaluated and was shown to agree with viscoelastic and dielectric data, clearly showing that thisrelaxation time should not be confused with the “effective” r obtained from the overall rate of thermodynamic recovery. These phenomena are common to polymers and nonpolymers, since both poly (vinyl acetate) and glucose were found to exhibit all of the physical properties that are essential to the behavior studied.The physics of slow relaxation processes in glass-forming liquids continue to interest many workers. Substantial progress has been made on the phenomenological understanding of the thermodynamic recovery process due no-tably to thework of Moynihan andco-workers, 1-3 and Kovacs and co-workers, 4, 5 through the introduction of the distribution of relaxationtimes superimposed on the nonlinear dependence of relaxation time on the change of the structure. Their fundamental differential equations are essentially the same nonlinear equation with distrib-uted order parameters. Moynihan (M model) invoked the Kohlrausch-Williams-Watts relaxationfunction, 6 while