화학공학소재연구정보센터
Rheologica Acta, Vol.33, No.4, 283-291, 1994
VISCOSITY OF CONCENTRATED SUSPENSIONS OF SPHERES
Difficulties associated with the viscosity measurement of concentrated suspensions of particulate solids in a liquid solvent can effectively be overcome with the falling needle technique reported here. The comparison of the settling (terminal) velocity of a given needle in a Newtonian solvent, with its terminal velocity in a suspension, yields the suspension viscosity ratio directly. The van den Brule and Jongschaap constitutive model describes our high concentration data best. Falling sphere data (diameter of sphere/diameter of suspended particle almost-equal-to 10) agree well with the falling needle data over the whole range (up to 40%) of solids concentrations used in our tests. In the opaque suspensions used, the passage of sedimenting needles and spheres was initially observed radiographically. Later tests used a more convenient technique using an inductance coil particle detector driven by a Colpitts oscillator.