TY - JOUR
T1 - Shear rheometry and visualization of glass fiber suspensions
AU - Marín-Santibáñez, Benjamín M.
AU - Pérez-González, José
AU - de Vargas, Lourdes
N1 - Funding Information:
This research was supported by CONACYT-CIAM (51837 K) and SIP-IPN (20070642, 20082313, and 20091012). B. M. Marín-Santibáñez had CONACYT and PIFI-IPN scholarships to carry out this work. J. Pérez-González and L. de Vargas are COFFA-EDI fellows.
PY - 2010/1
Y1 - 2010/1
N2 - The nonlinear rheological behavior of short glass fiber suspensions has been investigated in this work by rotational rheometry and flow visualization. A Newtonian and a Boger fluid (BF) were used as suspending media. The suspensions exhibited shear thinning in the semidilute regime and weaker shear thinning in the transition to the concentrated one. Normal stresses and relative viscosity were higher for the BF suspensions than for the Newtonian ones presumably due to enhanced hydrodynamic interactions resulting from BF elasticity. In addition, relative viscosity of the suspensions increased rapidly with fiber content, suggesting that the rheological behavior in the concentrated regime is dominated by mechanical contacts between fibers. Visualization of individual fibers and their interactions under flow allowed the detection of aggregates, which arise from adhesive contacts. The orientation states of the fibers were quantified by a second order tensor and fast Fourier transforms of the flow field images. Fully oriented states occurred for shear rates around 20 s-1. Finally, the energy required to orient the fibers was higher in step forward than in reversal flow experiments due to a change in the spatial distribution of fibers, from isotropic to planar oriented, during the forward experiments.
AB - The nonlinear rheological behavior of short glass fiber suspensions has been investigated in this work by rotational rheometry and flow visualization. A Newtonian and a Boger fluid (BF) were used as suspending media. The suspensions exhibited shear thinning in the semidilute regime and weaker shear thinning in the transition to the concentrated one. Normal stresses and relative viscosity were higher for the BF suspensions than for the Newtonian ones presumably due to enhanced hydrodynamic interactions resulting from BF elasticity. In addition, relative viscosity of the suspensions increased rapidly with fiber content, suggesting that the rheological behavior in the concentrated regime is dominated by mechanical contacts between fibers. Visualization of individual fibers and their interactions under flow allowed the detection of aggregates, which arise from adhesive contacts. The orientation states of the fibers were quantified by a second order tensor and fast Fourier transforms of the flow field images. Fully oriented states occurred for shear rates around 20 s-1. Finally, the energy required to orient the fibers was higher in step forward than in reversal flow experiments due to a change in the spatial distribution of fibers, from isotropic to planar oriented, during the forward experiments.
KW - Flocculation
KW - Glass fiber suspensions
KW - Newtonian and Boger fluid
KW - Rheometry
KW - Shear flow visualization
UR - http://www.scopus.com/inward/record.url?scp=77949272727&partnerID=8YFLogxK
U2 - 10.1007/s00397-009-0418-0
DO - 10.1007/s00397-009-0418-0
M3 - Artículo
SN - 0035-4511
VL - 49
SP - 177
EP - 189
JO - Rheologica Acta
JF - Rheologica Acta
IS - 2
ER -