title: Effect of organic and inorganic acids on concentrated chitosan solutions and gels.
abstract: Rheological properties of concentrated chitosan aqueous solutions and gels in the presence of different organic and inorganic acids were investigated. Viscosities of the solutions increased with polymer concentration and degree of ionization. Strong gels were obtained at pH around 2 with oxalic, phosphoric and sulfuric acids. Gelation was favored by simple and short chain length acids and was governed by ionic interactions. The gels could be distinguished from solutions by the frequency independence of their dynamic moduli and their high apparent activation energy for flow.
authors.affiliation: CREPEQ, Department of Chemical Engineering, Ecole Polytechnique, P.O. Box 6079, Station Centre-Ville, Montreal, Que., Canada H3C 3A7.
authors.forename: Mélina
authors.initials: M
authors.lastname: Hamdine
authors.forename: Marie-Claude
authors.initials: MC
authors.lastname: Heuzey
authors.forename: André
authors.initials: A
authors.lastname: Bégin
mesh_terms: D055592:Biophysical Phenomena; D001703:Biophysics; D048271:Chitosan / Q000737:chemistry*; D005782:Gels; D020100:Hydrogels; D006863:Hydrogen-Ion Concentration; D007477:Ions; D046911:Macromolecular Substances; D008853:Microscopy; D008956:Models, Chemical; D015233:Models, Statistical; D019815:Oxalic Acid / Q000737:chemistry; D010756:Phosphoric Acids / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D011208:Powders; D012212:Rheology; D055672:Static Electricity; D013464:Sulfuric Acids / Q000737:chemistry; D013696:Temperature; D013816:Thermodynamics; D013997:Time Factors
chemical_list: D005782:Gels; D020100:Hydrogels; D007477:Ions; D046911:Macromolecular Substances; D010756:Phosphoric Acids; D011108:Polymers; D011208:Powders; D013464:Sulfuric Acids; D048271:Chitosan; D019815:Oxalic Acid; C030242:phosphoric acid; C033158:sulfuric acid