非离子表面活性剂液晶的线性粘弹性研究

Studies on Linear Viscoelasticity of Liquid Crystal of a Nonionic Surfactant

用偏光显微镜测定了十二/十四烷基聚氧乙烯醚(C12～14EO7)/水二元体系相图的液晶区,用RS-75控制应力流变仪,在固定频率(f=0.0316Hz)时,对不同样品进行应力扫描.利用线性粘弹性区内流变参数G'与G′的比值tgδ对相转变敏感的特点来确定相结构的转变,并将结果与2H NMR结果相比较,两者吻合,这表明宏观测量手段能够反映微观相结构的变化规律.对于液晶实验结果采用弹簧-粘壶模型进行解释和讨论.

The liquid crystal zone for a nonionic surfactant (C12similar to14EO7)/water system was determined by using polarized light microscope. The stress sweep curves were tested (frequency = 0.0316 Hz) for several samples with RS - 75 rheostress meter. The ratio of loss modulus (G') and storage modulus (G'), i.e. tgdelta, was quite sensitive to the change of microstructure caused by a phase transition in linear viscoelasticity range. This property could be used to define the phase transition. The results of rheology were consistent with those of H-2 NMR. The data of the macro - rheologyical measurements reflected the rules of microstructure during the phase transition. The test results could be explained by the spring and dashpot model used in liquid crystal structure.