聚合物的玻璃化转变和孤立链的内旋转异构化能

玻璃化转变时的自由体积,对不同结构的聚合物不是常数,已由实验得到了说明。其原因是玻璃化转变时的体积膨胀系数部分地来自分子链构象变化的贡献。本文在文献2]和5]的基础上将Dimarzio定义的链倔硬能(?)与Lipotov关于玻璃化自由体积表达式联系起来,得到了T_g时的自由体积和孤立链的内旋转异构化能的关系式 上式的计算值和文献值较为一致,因此可以作为估算孤立链柔顺性参数的方法。

CORRELATION BETWEEN GLASSY TRANSFORMATION OF POLYMERS AND ENERGY OF ROTATIONAL ISOMERIZATION OF ISOLATED CHAINS

It has been shown that the free volume fraction at T, is not a universal parameter for linear polymers of different molecular structure. The reason is that the volume expansion at T, is partially contributed from the change of the numbers of conformations of isolated molecular chains due to internal rotation. In this paper, glassy transformation was connected with internal rotation of isolated molecular chains, and the relationship between free volume fraction of polymers at T, and energy e of rotationalisomerization of isolated molecular chains was formulated, g =The values of calculated from the above formula are in good agreement with those published in the literatures. Thus, the method described in this paper can be used to estimate a parameter for the flexibility of isolated molecular chains.