期刊名称：International Journal of Innovative Research in Science, Engineering and Technology
印刷版ISSN：2347-6710
电子版ISSN：2319-8753
出版年度：2014
卷号：3
期号：4
页码：11417
出版社：S&S Publications
摘要：Dynamic rheological behaviour, such as storage modulus (G') and loss modulus (G'') are measured as afunction of frequency at different temperatures in nematic region and also studied linear viscoelastic behaviour of p-nalkyl benzoic acid (nBA) mesogens. Different zones are exhibited by the samples, - a plateau zone at low frequencies, atransition zone at high frequencies and a zone entire plateau showing for crossover frequencies and relaxation times.The dependence of the elastic (G′) and loss (G′′) moduli on frequency is strong. The observed crossover points of G′, G′′in the study of frequency range is indicating that nematic phase of nBA has behaved like both viscoelastic solid andliquid for small deformations (<1% strain). A typical shear thinning behaviour of viscosity has been displayed when thesamples are subjected to shearing at a constant temperature. This typical shear thinning has approached slowly movingto Newtonian viscosity at high shear rates showing progressive development of nematic molecular orientation alongflow direction on increasing shear rate. Rheological behaviour of the nBA nematic phases is in general consistent likethe other reported compounds except the one thermotropic liquid crystals. The higher shear force and lower viscosityratio is observed in these compounds in which pentyl benzoic acid has high ratio indicating the high molecularorientation may be due to low chain entanglement.
