Effect of temperature on the flow properties of suspensions

Fine powder of CaCO₃ was dispersed in H₂O, ethylene, glycol (EG), and 50% aqueous solution of polyethylene glycol (PEG). In all cases, the apparent viscosity, η, of the suspensions decreased with temperature. The results are discussed on the basis of the energy dissipation theory. The total energy dissipation of flow, E_T(=η_aD²), per cm³ per sec was divided into two terms, i.e., E_p due to the interaction of flow units (flocs) and E_v, the viscous energy. E_v plays a dominant role when the viscosity of the medium, η_o, is large (e.g., for EG), whereas E_p is responsible for the overall flow behavior for the system with small η_o (e.g., for H₂O). From the analysis of E_p with respect to the rate of shear, D, and the effective floc concentration, a parameter m₂ was obtained, which is independent of D and of solid concentration, and serves as a measure of the extent of energy dissipation due to the interaction between flocs.