Rheological Properties and Scaling Laws of κ-Carrageenan in Aqueous Solution

Abstract

Rheological properties, gel network structures, and scaling laws for κ-carrageenan in aqueous solution were studied by rheology and field emission scanning electron microscopy (FESEM). The FESEM micrographs verified that the κ-carrageenan gels were formed by the formation of fibrils. The critical gel concentration, cg, obtained using the Winter–Chambon criterion, was found to be proportional to temperature as expressed by cg ∼ T0.85 where T is the temperature in °C. At the gel point, the critical relaxation exponent n obtained was a constant (n = 0.62) and independent of temperature. The critical gel strength Sg increased with increasing cg. A constant gel strength Sg/cg was obtained by normalizing Sg with cg to eliminate the effect of temperature, showing a unique character of κ-carrageenan in aqueous solution during gelation. The molecular structure of the junctions at the gel point was analyzed using the modified Eldridge–Ferry model, which supported the similarity of the fractal structure in the κ-car...