Gelation studies: Comparison of the critical exponents obtained by dynamic light scattering and rheology, 2(a) - A thermoreversible gelling system: Mixtures of xanthan gum and locust-bean gum

摘要

The sol-gel transition of two thermoreversible gelling mixtures made of xanthan gum and locust-bean gum has been studied by using in situ, time-resolved dynamic light scattering (DLS) and in situ theology. A critical dynamical behavior was observed near the sol-gel transition, which was characterized by the presence of power-law spectra over three and four decades in the time-intensity correlation function 92(t) - 1 similar to t(-mu) and over four and three decades in the oscillatory shear experiment G'(omega) similar to G"(omega)similar to omega(n) . A comparison of the critical exponents obtained (mu(1)approximate to 0.36, mu(2) approximate to 0.32 and n(1) approximate to 0.62, n(2) approximate to 0.67) was made as a function of the dependence of the two mixing ratios according to the theory by Doi and Onuki. New experiments were also performed to compare the critical exponents on such a thermoreversible system.