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Rheological Behavior and Structure of a Commercial Esterquat Surfactant Aqueous System
Author(s) -
Calero N.,
Alfaro M. C.,
Lluch M. Á.,
Berjano M.,
Muñoz J.
Publication year - 2010
Publication title -
chemical engineering and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.403
H-Index - 81
eISSN - 1521-4125
pISSN - 0930-7516
DOI - 10.1002/ceat.200900496
Subject(s) - viscoelasticity , pulmonary surfactant , rheology , materials science , aqueous solution , bilayer , plateau (mathematics) , modulus , shear (geology) , chemical engineering , relaxation (psychology) , newtonian fluid , vesicle , dispersion (optics) , composite material , shear flow , chemistry , thermodynamics , membrane , organic chemistry , optics , mathematics , psychology , mathematical analysis , social psychology , biochemistry , physics , engineering
Aqueous dispersions of a commercial esterquat‐type surfactant widely used in fabric softeners were rheologically characterized. While at 4 wt % esterquat concentration, a Newtonian response was observed; non‐Newtonian (Sisko) flow behavior and viscoelastic properties were found at 12 wt % and higher concentrations. The onset of nonlinear viscoelasticity in oscillatory shear provided interesting information on the strength of quiescent surfactant aggregates. Mechanical spectra corresponded to the plateau zone and the onset of the transition zone. The plateau modulus and the characteristic slopes of the relaxation spectra depended on the strength of the interactions among the aggregates. Start‐up at the inception of the shear experiments were carried out to obtain information on the time‐dependent shear behavior. Cryo‐SEM micrographs demonstrated the occurrence of a dispersion of vesicles embedded into a bilayer matrix.