Comparison of Two Different Commercially Available Polyacrylate Dispersants for Gelcasting Alumina Slurries

Abstract

Rheological behaviour of gelcast alumina slurries, prepared using different amounts of two commercially available dispersants, Darvan 821A and M-20C having difference in molecular weight, were studied. The optimum dispersant amount for each of the dispersants was determined in terms of attainment of minimum in the viscosity. The optimal amount of dispersant required was different for the two dispersants owing to the difference in molecular weight. The lowest viscosity value was found to be a little higher for M-20C based slurries, which could be attributed to the lesser electrosteric repulsion with M-20C as compared to that of Darvan. The differences in power law index value ‘n’ and also the thixotropy were directly correlated with the molecular weight of the dispersants.

Keywords:

• Rheology
• Alumina
• Dispersants
• Ammonium ployacrylate
• Polyelectrolyte and Thixotropy