Boehmite sols were obtained by peptizing boehmite precipitates with glacial acetic acid. The sols were aged at room temperature (30 ± 1°C) under closed condition. Rheological properties of the sols were studied at different ageing times. The sol characteristics were interpreted by measuring their viscosity, areas of hysteresis of the flow curves and yield stress (𝜏y). Viscosity and the area of hysteresis of the flow curves increased with increasing ageing time of the sols. A sharp change of yield stress was observed during the ageing period from 15 to 36 days. The change in viscous to elastic nature and the appearance of gel point of the sol was observed by studying their oscillatory flow behaviour, i.e. by measuring loss modulus (𝐺''), elastic modulus (𝐺'), and loss tangent (tan 𝛿) of the sols. Gel point of boehmite sol was found at 36 days of ageing under closed condition at room temperature (30 ± 1°C).
Volume 43, 2020
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