Click here to view fulltext PDF

Permanent link:
https://www.ias.ac.in/article/fulltext/boms/025/02/0115-0119

Boehmite sol; rheology; shear thinning; yield stress; viscoelasticity; gel point.

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 (𝜏_y). 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).

M K Naskar¹ M Chatterjee¹ D Ganguli^{2 3}

1. Sol-Gel Division, Central Glass and Ceramic Research Institute, Kolkata 700 032, India
2. Sol-Gel Division, Center Glass and Ceramic Research Institute, Kolkata 700 032, India
3. Department of Material Science, Indian Association for the Cultivation of Science, Kolkata 700 032, India

Published

April 2002

Manuscript received

11 September 2001

Manuscript revised

22 February 2002