首页 | 本学科首页   官方微博 | 高级检索  
    按 检索      


Simple-Complex Fluid Transition in Microemulsions
Authors:Imen Ben Naceur  Moez Guettari  Ghazi Kassab  Tahar Tajouri
Institution:Unité de recherche RMN des polymères et des composites, Tunis Preparatory Engineering Institute , University of Tunis , Tunisia
Abstract:The aim of this work was to study the rheological behavior of water in-oil microemulsion formulated with AOT (sodium bis(2-ethylhexyl) sulfoccinate) in isooctane over a temperature range from 25°C to 55°C for the oil/AOT volume fraction φ m =0.1 and various AOT and H2O molar ratios, W0, ranging from 0 to 45. The apparent viscosity was measured vs. shear rate by a rotational concentric cylinder viscometer. It was shown that above /></span> s<sup>?1</sup>, the solutions utilized behaved as Newtonian liquids. The absolute viscosities were deduced from the shear stress- shear rate rheograms. For W<sub>0</sub> < 17, the solutions behaved as simple fluids, where the viscosities decrease as the temperature increases. However, an opposite behavior was observed for W<sub>0</sub> > 17; the viscosity remained constant and then increased above a critical temperature, T<sub>c</sub>, depending on W<sub>0</sub>. For the molar ratio W<sub>0,c</sub> = 17; the studied viscosity remained constant, η(W<sub>0,c</sub>) = (1.17 ± 0.04) cP, for the temperature range studied. Thus, a simple–complex fluid transition was evident in the studied system. For the simple fluids, W<sub>0</sub> < W<sub>0,c</sub>, the total activation energy vs. W<sub>0</sub> showed three linear parts. The different slopes were attributed to the change of the microscopic structure of the formed micelles. For the critical molar ratio W<sub>0,c</sub> = 17, the total activation energy vanished. So, according to the Eyring lattice model, the jump of the formed micelles from one site to another was not permitted and the entire molecular groups were in vibration and rotation motions. For W<sub>0</sub> > W<sub>0,c</sub>, where the formed micelles were fully hydrated, the relative viscosity of the studied solutions vs. temperature was fitted according a polynomial law, where the exponent was found to be dependent on W<sub>0</sub>.</td> </tr> <tr> <td align=
Keywords:complex fluid  reverse micelle  rheology  simple fluid  transition
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号