Influence of energy input on suspension properties

Electrosteric stabilization of a commercially available boehmite powder in water was investigated to perform milling experiments and reduce the particle size to the nanoscale range. The effect of three sodium polyacrylate dispersants (Na-PA) with different molar masses (2,100, 8,000, 15,000 g/mol) on the suspension properties before and after milling experiments was assessed by electroacoustic measurements in comparison with rheological tests. A significant loss of the stabilizing effect of the sodium polyacrylates due to the application of mechanical energy was detectable. Measurements of the adsorbed amount of the dispersants after milling via detection of the COD in the background solution show a considerable desorption from the particle surface. Accessorily performed analyses of the molar mass of the polymers yielded a destruction of the polymer chains due to the mechanical energy.