Abstract
Drag reduction, shear and extensional rheometry, and cryogenic transmission electron microscopy (cryo-TEM) were used to study aqueous solutions of one cationic surfactant, Arquad 16-50 (5 mM), with three isomeric counterions, 2-, 3-, or 4-Cl-benzoate at 12.5 mM. Each isomer showed different types of rheological and drag reduction behavior and different micellar structures. The 4-Cl system showed good drag reduction, high apparent extensional viscosity, and a thread-like micellar network, while the 2-Cl system showed no drag reduction, low apparent extensional viscosity, and only spherical micelles. The 3-Cl system was drag reducing and had high extensional viscosities at 30 °C. However, at 20 °C, the 3-Cl solution precipitated at high shear or extensional rates, leading to loss of drag reduction and low apparent extensional viscosity. The 3-Cl at 20 °C showed threadlike structures in some pictures and vesicles in others, presumably because of variations in the level of shear the samples were subjected to ...
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have