TY - JOUR
T1 - Instabilities of micellar systems under homogeneous and non-homogeneous flow conditions
AU - Méndez-Sánchez, Arturo F.
AU - López-González, M. Rosario
AU - Rolón-Garrido, V. Hugo
AU - Pérez-González, José
AU - de Vargas, Lourdes
PY - 2003/1
Y1 - 2003/1
N2 - The rheological behavior of a cetylpyridinium chloride 100 mmol 1-1/sodium salicylate 60 mmol 1-1 aqueous solution was studied in this work under homogeneous (cone and plate) and nonhomogeneous flow conditions (vane-bob and capillary rheometers), respectively. Instabilities consistent with non-monotonic flow curves were observed in all cases and the solution exhibited similar behavior under the different flow conditions. Hysteresis and the sigmoidal flow curve suggested as characteristic of systems that show constitutive instabilities were observed when running cycles of increasing and decreasing stress or shear rate, respectively. This information, together with a detailed determination of steady states at shear stresses close to the onset of the instabilities, allowed one to show unequivocally that "top and bottom jumping" are the mechanisms to trigger the instabilities in this micellar system. It is shown in addition that there is not a true plateau region in between the "top and bottom jumping". Finally, the flow behavior beyond the upturn seemed to be unstable and was found accompanied by an apparent violation of the no-slip boundary condition.
AB - The rheological behavior of a cetylpyridinium chloride 100 mmol 1-1/sodium salicylate 60 mmol 1-1 aqueous solution was studied in this work under homogeneous (cone and plate) and nonhomogeneous flow conditions (vane-bob and capillary rheometers), respectively. Instabilities consistent with non-monotonic flow curves were observed in all cases and the solution exhibited similar behavior under the different flow conditions. Hysteresis and the sigmoidal flow curve suggested as characteristic of systems that show constitutive instabilities were observed when running cycles of increasing and decreasing stress or shear rate, respectively. This information, together with a detailed determination of steady states at shear stresses close to the onset of the instabilities, allowed one to show unequivocally that "top and bottom jumping" are the mechanisms to trigger the instabilities in this micellar system. It is shown in addition that there is not a true plateau region in between the "top and bottom jumping". Finally, the flow behavior beyond the upturn seemed to be unstable and was found accompanied by an apparent violation of the no-slip boundary condition.
KW - Flow instabilities
KW - Homogeneous and non-homogeneous flow
KW - Micellar solutions
KW - Slip
KW - Top and bottom jumping
UR - http://www.scopus.com/inward/record.url?scp=0037284319&partnerID=8YFLogxK
U2 - 10.1007/s00397-002-0254-y
DO - 10.1007/s00397-002-0254-y
M3 - Artículo
SN - 0035-4511
VL - 42
SP - 56
EP - 63
JO - Rheologica Acta
JF - Rheologica Acta
IS - 1
ER -