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首页> 外文期刊>Journal of Applied Polymer Science >INFLUENCE OF DILUTION BY POLYDIMETHYLSILOXANE ON ELECTRORHEOLOGICAL EFFECT OF SIDE-CHAIN LIQUID CRYSTALLINE POLYSILOXANE
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INFLUENCE OF DILUTION BY POLYDIMETHYLSILOXANE ON ELECTRORHEOLOGICAL EFFECT OF SIDE-CHAIN LIQUID CRYSTALLINE POLYSILOXANE

机译：聚二甲基硅氧烷的稀释对侧链液晶聚硅氧烷的流变电学影响

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摘要

A liquid crystalline polysiloxane (LCP), having an ether bond in the spacer between its siloxane main chain and its mesogenic-group side chains, exhibited a very small electrorheological (ER) effect or increase in shear stress upon application of an electric field, but mixtures of the LCP and polydimethylsiloxane (PDMS) exhibited a sharply increasing ER effect with increasing PDMS content throughout the tested range of up to 0.5 of PDMS weight fraction. When phenyl-substituted PDMS (Ph-PDMS) at a weight fraction of 0.3 was used instead of PDMS, however, the ER effect decreased with increasing phenyl content and became nearly undetectable with Ph-PDMS having a phenyl content (ratio of substituted phenyl groups to initial methyl groups) of approximately 15%. DSC analyses showed that the ER effect of the LCP/PDMS mixtures occurred undiminished throughout a temperature range in which LCP itself is an isotropic Liquid in the absence of an applied electric field and suggested that the LC structure of the LCP was maintained even when it was diluted with PDMS in weight fractions of 0.5 or higher, but disrupted when diluted by a 0.3 weight fraction of Ph-PDMS having a 15% phenyl content. Optical microscopic observation of the mixtures of the LCP with a 0.3 weight fraction of PDMS or Ph-PDMS (15% phenyl content) showed that both consisted of uniformly dispersed micron-sized droplets which became elongated in the direction of the applied electric field when it was applied alone but became smaller when both the electric held and shear were applied. These results suggest that the phase separation between the LCP and the dilution oil, as well as the existence and orientation of LC domains, is essential for the generation of a large ER effect. (C) 1997 John Wiley & Sons, Inc. [References: 28]
机译：液晶聚硅氧烷（LCP）在其硅氧烷主链和介晶基团侧链之间的间隔基中具有醚键，在施加电场时表现​​出很小的电流变（ER）效应或剪切应力增加，但是在整个测试范围内，LCP和聚二甲基硅氧烷（PDMS）的混合物在PDMS重量分数高达0.5的范围内，随着PDMS含量的增加，其ER效应也急剧增加。但是，当使用重量分数为0.3的苯基取代的PDMS（Ph-PDMS）代替PDMS时，ER效应会随着苯基含量的增加而降低，而对于具有苯基含量的Ph-PDMS（取代苯基的比率）几乎无法检测到（大约为起始甲基）的大约15％。 DSC分析表明，在没有施加电场的情况下，LCP / PDMS混合物的ER效应在LCP本身是各向同性液体的整个温度范围内都没有减弱，并且表明LCP / PDMS混合物即使在LCP / PDMS处于液态时也保持LC结构用PDMS稀释后的重量分数为0.5或更高，但当用0.3重量分数的苯基含量为15％的Ph-PDMS稀释时会被破坏。光学显微镜观察LCP与PDMS或Ph-PDMS的0.3重量分数（苯基含量为15％）的混合物，发现两者均由均匀分散的微米级液滴组成，当液滴进入时，它们沿施加的电场方向拉长单独施加，但同时施加电保持力和剪切力时变小。这些结果表明，LCP和稀释油之间的相分离以及LC结构域的存在和取向对于产生大的ER效应至关重要。 （C）1997 John Wiley＆Sons，Inc. [参考：28]

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