Microscopic Structure and Flow Behavior of Aqueous Suspension of Core-Shell Type Carboxylated Acrylic Particles

Abstract

Microscopic structure of core-shell type carboxylated acrylic particles in aqueous suspension was studied by dynamic measurements and small-angle X-ray scattering, experiments, and relationship between the structure and flow behavior of the suspension was discussed. As the particle swells by addition of amine, the suspensions of various apparent volume fraction were prepared by changing amounts of 2-dimethylaminoethanol. Flow behavior was estimated by steady shear measurements.Flow behavior of the suspensions changes from Newtonian to pseudoplastic as apparent volume fraction increases. The suspensions of Newtonian flow in the all shear rate region (10-1s-1≤γ≤103s-1) have no flocculated structures. The suspensions of Newtonian flow in a lower shear rate region and pseudoplastic flow in a higher shear rate region have flocculated domain structures. The suspensions of pseudoplastic flow in all the shear rate region have three dimensional network structure. Both domain structure and three dimensional network structure are lattice-like ordered structures of the particles, and distance between two center of the particles in the ordered structures is 126nm. Creation of the ordered structure changes the suspension flow from Newtonian to pseudoplastic.