Dual electrorheological and giant electrorheological behaviors of modified calcium titanyl oxalate suspensions

초록

Two types of giant electrorheological (GER) material based on calcium titanyl oxalate (CTO) have been successfully synthesized. One type is CTO modified by sodium dodecyl sulfate (SCTO), while the other is coated with urea (UCTO). Their morphologies were examined using scanning electron microscope and transmission electron microscope, while their chemical and crystal structures, and thermal properties were studied using FTIR, x-ray diffraction and thermogravimetric analysis, respectively. The two types of GER material were dispersed in silicone oil at particle concentrations of 15 and 60 vol% to investigate their rheological properties, including flow curves, yield stress and dielectric behavior. The results show that particle concentration markedly influences the field-responsive rheological behavior of GER materials. A suspension with a low concentration (15 vol%) demonstrates typical electrorheological (ER) fluid characteristics, whereas a suspension with a high concentration (60 vol%) exhibits GER behavior. When an electric field was applied, the flow curve of the ER fluid (15 vol%) was fitted using the Cho–Choi–Jhon equation, whereas the flow curve of the GER fluid (60 vol%) was more accurately fitted using the Herschel–Bulkley equation. The effect of electric field strength on the yield stress of ER and GER fluids exhibits different trends and slopes. Additionally, the universal yield stresses of ER and GER fluids were analyzed separately. Using a recently developed theory based on the concept of glueon particles, all yield stress values for each fluid can be reduced to a single curve, demonstrating their relevance to the universal yield stress equation. © 2026 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved. This article is available under the terms of the IOP-Standard License.

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