Thixotropic yielding behavior of MLPS colloidal suspension

Visualizing flow dynamics and restart of Carbopol gel solutions in tube and parallel-plates geometries with wall slip

“…As shear stress increased, the shear rate curves enabled the identification of a second flow regime, which was affected by wall slip (S-R). This regime was established considering the observations reported by Divoux et al, 97 where it is determined that wall slip occurs when there is an adhesive failure 53 between the internal wall boundaries of the geometry and the material, i.e., the material starts to flow because the applied stress exceeds the slip static yield stress (t slip-sy ), 63,70,[98][99][100][101] and is reflected in relatively low values of shear rate and angular velocity. The behavior of these two variables observed in Fig.…”

“…Numerous rheometric studies have analyzed the flow of yield stress fluids, confirming the presence of wall slip, and its influence on the rheological properties of these materials. 43,44,46,[62][63][64][65][66] Some studies carried out include a physical description of the slip phenomenon; 16,67 others suggest the use of geometries for rheometric tests such as vane in cup, 68,69 rough solid surfaces between parallel plates geometries, 61,70 concentric cylinders in contact with the sample that minimizes slip, 71,72 and visualization techniques for rheological characterization. 69,73 In contrast to the numerous rheometric studies, there are fewer experimental researches analyzing the flow kinematics, which is an essential factor for better understanding of the influence of rheological properties such as yield stress, and phenomena like wall slip on flow restart.…”