Rheological analysis of highly pigmented inks: Flocculation at high temperatures

Steady and dynamic shear rheological properties of açai pulp (Euterpe oleraceae Mart.)

“…Since the pulp is rich in fibers, lipids and proteins, these elements probably interacted in a complex way and, as the heating with agitation increased, the network of interactions was affected due to a rearrangement of the relative positions of the different elements (Coussot, 2007). Thus, the increased viscosity at low deformations and higher temperatures could be attributed to a combination of factors such as (a) formation of a protein network (Abu-Jdayil, 2003); (b) enhancement of droplet coalescence (Saiki and Prestidge, 2005); and/or (c) a probable depletion-flocculation of large particles (Fernández et al, 1998) associated with the presence of proteins and fibers (polysaccharides).…”

The effect of temperature on the yield stress of mineral suspensions

“…He et al [4] measured, through extrapolation of steady state shear rheological data, a decrease in τ y of 16% with increasing temperature from 25 to 40 • C for a fine particle limestone slurry. In studies on more complex systems, also employing either extrapolative measurement of τ y or determination from rheological model fitting, a decrease in τ y with increasing temperature was also observed for zirconia-wax [5] and metal injection moulding suspensions [6] In contrast, Yang et al [7] observed a decrease followed by an increase in τ y with temperature for titanium dioxide suspensions measured directly via the vane technique and Fernandez et al [8] measured an increase in τ y with temperature for pigmented inks via stress ramp tests. Of the studies listed above, a notable characteristic of those which observed a decrease in τ y with temperature was that τ y was determined via either extrapolation of, or fitting to, steady state rheological data.…”

Dynamics of formation and dripping of drops of deformation-rate-thinning and -thickening liquids from capillary tubes

“…For example, Pangalos et al [14], who have carried out a detailed study of rheological properties of news inks of varying compositions, have found all of the inks that they studied to be rate-thinning. More recently, Fernandez et al [15] have carried out a similar study and reported on rate-thinning as well as viscoelastic properties of highly pigmented inks. It is well-known that non-Newtonian liquids can exhibit responses that differ drastically from those of Newtonian liquids in most free surface flows and not just in drop formation.…”

“…., in Eqs. (2), (4), and (5) into which the expansions (13)- (15) have been substituted, a set of equations of different orders in "r" is obtained. The leading order equations that result from the kinematic boundary condition (4), the normal and tangential components of the traction boundary condition (5), and the z-component of the momentum equation (2) are…”