Use of High Molecular Weight Thickeners

As discussed above, high molecular weight materials such as hydroxyethyl cellulose or xanthan gum will, when added above a critical concentration (at which polymer coil overlap occurs), produce very high viscosity at low stresses or shear rates (usually in excess of several hundred Pa s) and this will prevent sedimentation of the particles. 

Use of Mixtures of Polymers and Hnely Divided Particulate Solids 

By combining the thickeners such as hydroxyethyl ceHulose or xanthan gum with particulate solids such as sodium montmorillonite, a more robust gel structure could be produced. This gel structure may be less temperature dependent and could be optimised by controlling the ratio of the polymer and the particles. 

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