Loshkarev Alexander A, Vlasova Maria F, Sapronova Natalya I, Tokunov Yuri M, Volkov Ivan A, Ivanov Victor V, Maeder Thomas
Moscow Institute of Physics and Technology (State University), Institutskii per. 9, Dolgoprudny, Moscow Region 141701, Russia.
École Polytechnique Fédérale de Lausanne, BM 3108 (Bâtiment BM), Station 17, CH-1015, Lausanne, Switzerland.
MethodsX. 2017 Sep 21;4:305-309. doi: 10.1016/j.mex.2017.09.002. eCollection 2017.
A method for determining the critical values of the flow speed and the flow constriction degree characteristic of the alignment of cylindrical nano-objects in a flowing suspension is proposed. Previously, the alignment process of cylindrical nano-objects in suspensions was investigated by using birefringence of the polarized light and the small-angle X-ray scattering. While both methods are suitable for measuring the alignment degree of cylindrical nano-objects in suspensions diluted down to low concentrations, they are restricted for the application to undiluted concentrated suspensions because of non-transparency and multiple scattering of X-rays. In addition, the use of the second method requires an expensive synchrotron equipment. We present a simple and faster method based on the direct ultrasound attenuation measurements of longitudinal viscosity of a suspension containing cylindrical nano-objects, which decreases monotonically, approaching its asymptotic value with increase in the flow speed and the flow constriction degree. The principle and advantages of the proposed method are as follows: •The cylindrical nano-objects align along an accelerated flow at overcritical values of the flow speed and the constriction degree.•The critical values correspond to the state of a suspension possessing viscosity close to the asymptotic value.•The method is applicable to undiluted concentrated suspensions, including opaque ones.
