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Rheological and Coating Properties of Modified Silica Sols

Research paper by J. Marx, R. Lischewski, R. Schnabel, F. Apsel, H. Böttcher

Indexed on: 01 Jan '98Published on: 01 Jan '98Published in: Journal of Sol-Gel Science and Technology



Abstract

The rheological behavior of modified silica sols has been investigated by gel formation kinetics and dynamic flowing within the pH range 3–7 and the temperature range 20–50°C. The sols show pseudo-plastic behavior at low shear-rates, with Newtonian behavior below 100 s−1. Oscillation measurements reveal that gelation starts with a significant decrease of phase difference <10°, because of a strong increase in elastic behavior. After solidification the values of phase difference increase, indicating a partial destruction of the gel structure due to stress. The relationship between the viscosity of the modified silica sols and their coating parameters was compared for both dip coating and continuous coating with a slide coating unit.