Rate‐determining factors for enthalpy relaxation of glassy polymers. Molecular weight
Rate‐determining factors for enthalpy relaxation of glassy polymers. Molecular weight
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玻璃态聚合物分子量弛豫的速率决定因素。
DOI：
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发表时间：
1975
期刊：
影响因子：
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通讯作者：
S. Petrie
中科院分区：
文献类型：
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作者：
A. S. Marshall;S. Petrie
为了获得关于分子质量对与非平衡热力学状态相关的弛豫过程中分子迁移率的影响的信息，对不同分子量的玻璃态无规聚苯乙烯进行了焓弛豫研究，范围从2.0×103到811×103。正如以前在有机玻璃的焓弛豫研究中发现的那样，玻璃化转变温度Tg是主要的速率决定因素。然而，从更详细的数据分析来看，很明显，在Tg以下相应温度区间的弛豫过程是分子量的函数。弛豫速率随分子量的增加而减小，并接近于分子量为50×103附近的一个极限值，这是玻璃化转变依赖于分子量的临界分子量范围。对于Aroclor 5460，一种分子量较低但具有…
In order to obtain information concerning the effect of molecular weight on the molecular mobility involved in the relaxation processes associated with the nonequilibrium thermodynamic state of glassy polymers, enthalpy‐relaxation studies have been undertaken on glassy atactic polystyrenes of various molecular weights, ranging from 2.0×103 to 811×103. As was found in previous studies of enthalpy relaxation in organic glasses, the glass transition temperature Tg is the principal rate‐determining factor. From a more detailed analysis of the data, however, it is evident that the relaxation processes at corresponding temperature intervals below Tg are a function of the molecular weight. The relaxation rate decreases somewhat with increasing molecular weight and approaches a limiting value at molecular weights in the vicinity of 50×103, the critical molecular‐weight range in the molecular‐weight dependence of glass transformation. For Aroclor 5460, a nonpolymeric material of lower molecular weight but having a...