甲基纤维素/二氯乙酸液晶溶液的相转变

本文研究了甲基纤维素/二氯乙酸液晶溶液液晶相与各向同性相之间相互转变的过程。在连续升温过程中,由于液晶相内部有序度的非均一性,升温速率对液晶相织构随温度的变化有较大的影响。在等温相转变过程中,无论是从各向同性态转变为液晶态,还是其逆过程,从液晶态转变为各向同性态,相转变曲线均具有指数方程特征。利用与 Avrami 方程相似的指数方程进行处理,在从各向同性态转变为液晶态时,指数 n 大部分约为1。但液晶相向各向同性相在低于 Tc 时的相转变中,n 均小于1。相转变速率受溶液浓度和温度的影响。在质量分数为0.259的浓度时,液晶相向各向同性相的转变在低于 Tc 时39.5℃进行得最快。

THE PHASE TRANSITIONS OF METHYL CELLULOSE/DICHLOROACETIC ACID LIQUID CRYSTALLINE SOLUTIONS

The phase transition between isotropic and anisotropic phases of methyl cellulose/dichloroacetic acid solutions was studied.When heating the solution,the variation of the mesophase texture was influenced by the heating rate because the degree of ordering was heterogeneous within the mesophase.In the isothermal phase transition,the transitions both from mesophase to isotropic phase and from isotropic phase to mesophase could be described by an exponent equation.In most cases,the exponent was about 1 for the phase transition from the isotropic to anisotropic phases and smaller than 1 for that from the mesophase to the isotropic phase at the temperature lower than T_c.The rate of the phase transition was affected by the solution concentration and temperature.When the concentration ω was 0.259,the phase transition from the mesophase to the isotropic phase at the temperature lower than T_c was fastest at about 39.5℃.