Electrorheological properties of mechanically activated gibbsite

Chan-e in the surface state during milling of gibbsite (GB) is elucidated by electrorheological properties of the suspension comprising GB and silicone oil. Under de electrical field up to 2 kV/mm, milling brings about remarkable increase in the yield stress, e.g., milling GB for 3 h increases 100 times the yield stress at 2 kV/mm. Amount of thermal dehydration below 200 degreesC, A(OH<200), increases by milling as a consequence of mechanochemical dehydration and readsorption. The yield stress increases quasi proportionally with A(OH<200). Thus, ER yield stress of GB serves as a quantitative measure of mechanochemical dehydration of GB. (C) 2001 Elsevier Science Ltd. All rights reserved.