Aqueous dispersions of gelled collagen particles. Part 1: experimental characterization of stiffness and rheological properties

Purpose To study the rheological behavior of aqueous dispersions of collagen gelled media and to bring it into relation with the gel stiffness and microstructure. Design/methodology/approach Collagen gelled media were prepared at different concentrations and their stiffness was measured with dynamic elastic modulus (DEM) technique. The gelled media were reduced into dispersions of micelles and gel liquid phase and the apparent viscosity of these systems was investigated as a function of the gap thickness, the shear rate and the collagen concentration. The gap thickness was varied between 20 and 200 μm. The microstructure of the broken gelled media was finally explored with optical microscopy. Findings DEM analysis has given values of the collagen gel stiffness ranging between 3 × 10−4 and 3.3 × 10−3 MPa. It has been shown that apparent viscosity grows with the increase of the gap thickness from 2 to 5 Pa s at constant collagen concentration and applied shear rate (4 percent, 100 s−1). A rise in the collagen concentration has produced an increase in the apparent viscosity of gelled media dispersions. Nevertheless, the phenomenological law does not obey previously proposed equations but follows a sigmoid modal. Shear‐thinning phenomenon has been observed when the shear rate is varied between 10 and 2,000 s−1. Research limitations/implications The gel breaking process, which may cause changes in the microstructure of the micelles and hence in the rheological behavior of the dispersions, should be characterized measuring the forces acting on the samples during the rupture. Originality/value The paper provides useful information on the rheological behavior of aqueous dispersions of collagen gelled media.