Gelation Studies: Comparison of the Critical Exponents Obtained by Dynamic Light Scattering and Rheology, 2

✍ Scribed by Sven Richter; Volodymyr Boyko; Rolf Matzker; Klaus Schröter

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 147 KB
• Volume: 25
• Category: Article
• ISSN: 1022-1336
• DOI: 10.1002/marc.200400214

✦ Synopsis

Abstract

Summary: 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 rheology. 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 g~2~(t) − 1 ∼ t^−μ^ and over four and three decades in the oscillatory shear experiment G′(ω) ∼ G″(ω) ∼ ω^n^. A comparison of the critical exponents obtained (μ~1~ ≈ 0.36, μ~2~ ≈ 0.32 and n~1~ ≈ 0.62, n~2~ ≈ 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.

Double‐logarithmic plot of the time‐intensity correlation functions g~2~(t) − 1 versus the delay time, t, at a 90° scattering angle and at several temperatures of the mixture 1.

imageDouble‐logarithmic plot of the time‐intensity correlation functions g~2~(t) − 1 versus the delay time, t, at a 90° scattering angle and at several temperatures of the mixture 1.