title: Combined rheological and ultrasonic study of alginate and pectin gels near the sol-gel transition.
abstract: The sol-gel transition of biopolymer mixtures has been investigated by rheological and ultrasonic measurements. A scaling analysis of the data was performed for both types of measurements. A gel time was determined from rheology for the pure pectin samples, and the data could be fitted to a universal scaling form near the transition point. Its critical exponents are in good agreement with the predictions of scalar percolation theory. In addition, the ultrasonic signal of the pectin samples close to the transition was analyzed in terms of a high-frequency scaling approach for the attenuation and the velocity. For the alginate samples and the mixtures, for which the gel point cannot be determined reliably from rheology, the ultrasonic measurements were analyzed using the same scaling form as for the pectin sample, thus providing a method for estimating the gel point, even in the absence of rheological data.
authors.affiliation: Biopolymères, Interactions, Assemblages UR 1268, Institut National de la Recherche Agronomique, B.P. 71627, Nantes CEDEX 03, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Audebrand
authors.forename: Max
authors.initials: M
authors.lastname: Kolb
authors.forename: Monique A V
authors.initials: MA
authors.lastname: Axelos
mesh_terms: D000464:Alginates / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry; D001709:Biotechnology / Q000379:methods; D004853:Epoxy Resins / Q000737:chemistry; D005782:Gels; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D009991:Oscillometry; D010368:Pectins / Q000737:chemistry*; D044367:Phase Transition; D011108:Polymers / Q000737:chemistry; D012212:Rheology / Q000379:methods; D013816:Thermodynamics; D013997:Time Factors; D014465:Ultrasonics
chemical_list: D000464:Alginates; D001672:Biocompatible Materials; D004853:Epoxy Resins; D005782:Gels; D006603:Hexuronic Acids; D011108:Polymers; D010368:Pectins; D020723:Glucuronic Acid