Linear viscoelastic properties of ordered latices

Abstract

The frequency-dependent behavior of the storage modulus G′ and loss modulus G″ has been measured for an ordered latex at different volume fractions. From these measurements the volume fraction dependency of the static shear modulus was obtained. The theoretical static shear modulus has been deduced from a stress tensor expression which only takes into account the electrostatic pair interactions between nearest neighbors. The electrostatic pair interaction is modeled adequately to account for the multiparticle environment of a particle and for high surface charges. The interactions are described by the linear superposition approximation for the pair interaction energy between two particles given by Bell et al. [J. Colloid Interface Sci. 33, 335 (1970)]. The apparent surface potential and the effective Debije screening length used in this expression are determined from the electrostatic potential which is numerically determined from the Poisson–Boltzmann equation in a spherical cell. The theoretical model is also compared with measurements of several other investigators. Most of the experimental data can be scaled to a single mastercurve resulting from the proposed theoretical model.

Consistent Surface Potentials from Bulk Suspension Properties

“…[11] and [12] are based on the same form of particle interaction energy and suspension microstructure, V…”

“…The prefactors and arguments of the exponential fit were then plotted as a function of f/f max . The tions reported here will be compared with three similar models proposed by van der Vorst et al (11), Buscall et al (12), and prefactors are well described by a linear function of f/f max , while the argument is a power law function of f/f max .…”

“…Many models of the shear modulus of dense suspensions of charge-stabilized particles have been developed and have met with varying degrees of success (3,(10)(11)(12). Direct computation of a modulus is difficult and requires assumpwhere the constant, k, is the Debye screening length tions about how the pairs contribute and the suspension mi-(Eq.…”

“…A plot of Models of the elastic modulus have been considered by several authors (3,(10)(11)(12). Most are based on the harmonic dimensionless osmotic pressure versus ks was made at a constant value of f/f max .…”

Mechanical characterization of network formation during heat-induced gelation of whey protein dispersions

“…16,19 -24 It is, therefore, anticipated that the mechanical pathway of the sol-to-gel transition of such a globular protein colloid is quite different from that of an ordinary cross-linking polymer, explained by the percolation theory. 10,11 In the field of colloid sciences, it has been known for years that charged colloidal particles in an aqueous solution can arrange into a crystalline lattice, [25][26][27][28] if strong interparticle repulsive forces exist, and such a colloidal dispersion is designated as a colloid crystal. A colloid crystal responds to a sufficiently small deformation as if it were a solid.…”