title: Rheological behavior of aqueous dispersions containing blends of rhamsan and welan polysaccharides with an eco-friendly surfactant.
abstract: Small amplitude oscillatory shear and steady shear flow properties of rhamsan gum and welan gum dispersions containing an eco-friendly surfactant (a polyoxyethylene glycerol ester) formulated to mimic the continuous phase of O/W emulsions were studied using the surface response methodology. A second order polynomial equation fitted the influence of surfactant concentration, rhamsan/welan mass ratio and total concentration of polysaccharides. Systems containing blends of rhamsan and welan did not show synergism but thermodynamic incompatibility and made it possible to adjust the linear viscoelastic and low shear rate flow properties to achieve values in between those of systems containing either rhamsan or welan as the only polysaccharide. All the systems studied exhibited weak gel rheological properties as the mechanical spectra displayed the plateau or rubber-like relaxation zone, the linear viscoelastic range was rather narrow and flow curves presented shear thinning behavior, which fitted the power-law equation. While mechanical spectra of the systems studied demonstrated that they did not control the linear viscoelastic properties of the corresponding emulsions, the blend of rhamsan and welan gums was able to control the steady shear flow properties.
authors.affiliation: Reología Aplicada, Tecnología de Coloides, Departamento de Ingeniería Química, Facultad de Química, Universidad de Sevilla C/P, García González, 1, E41012 Sevilla, Spain.
authors.forename: L A
authors.initials: LA
authors.lastname: Trujillo-Cayado
authors.affiliation: Reología Aplicada, Tecnología de Coloides, Departamento de Ingeniería Química, Facultad de Química, Universidad de Sevilla C/P, García González, 1, E41012 Sevilla, Spain.
authors.forename: M C
authors.initials: MC
authors.lastname: Alfaro
authors.affiliation: CEER-Biosystems Engineering, Instituto Superior de Agronomia, University of Lisbon, Tapada da Ajuda, 1349-017 Lisboa, Portugal.
authors.forename: A
authors.initials: A
authors.lastname: Raymundo
authors.affiliation: CEER-Biosystems Engineering, Instituto Superior de Agronomia, University of Lisbon, Tapada da Ajuda, 1349-017 Lisboa, Portugal.
authors.forename: I
authors.initials: I
authors.lastname: Sousa
authors.affiliation: Reología Aplicada, Tecnología de Coloides, Departamento de Ingeniería Química, Facultad de Química, Universidad de Sevilla C/P, García González, 1, E41012 Sevilla, Spain. Electronic address: jmunoz@us.es.
authors.forename: J
authors.initials: J
authors.lastname: Muñoz
mesh_terms: D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D012212:Rheology / Q000379:methods*; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D011135:Polysaccharides, Bacterial; D013501:Surface-Active Agents; C071623:rhamsan; C068570:welan
keywords: Eco-friendly surfactant; Response surface methodology; Rhamsan gum; Rheology; Welan gum