Dynamics and extensional rheology of polymer–surfactant association complexes

Abstract

Understanding and characterizing the influence of polymers and surfactants on rheology, application, and processing is critical for designing complex fluid formulations for enhanced oil recovery, pharmaceuticals, cosmetics, foods, inks, agricultural...

Rheology and Pinching Dynamics of Associative Polysaccharide Solutions

“…In each case, it is essential to characterize and understand the rate-dependent response of the rheologically complex fluid to the large imposed shear and extensional deformation rate characteristic of coating operations. Furthermore, as interactions of hydrophobic stickers with surfactants and other additives can alter the magnitude of their influence, careful investigations of model formulations are needed. ,,,,,,, We anticipate that the results and insights presented in this study will inspire future research into the macromolecular engineering of thickeners or rheology modifiers and formulations.…”

“…Furthermore, as interactions of hydrophobic stickers with surfactants and other additives can alter the magnitude of their influence, careful investigations of model formulations are needed. 20,38,39,43,105,148,173,174 We anticipate that the results and insights presented in this study will inspire future research into the macromolecular engineering of thickeners or rheology modifiers and formulations.…”

Evaporation and Rheology Chart the Processability Map for Centrifugal Force Spinning

“…The DoS videos are analyzed with ImageJ and specially written MATLAB codes to determine the minimum neck radius as a function of time. The DoS rheometry setup, design considerations, specific advantages contrasted to other extensional rheology methods, and various approaches to analyzing datasets are detailed in our previous contributions, − ,,,− and in several recent studies. − We used a closed transparent cell to carry out experiments in an atmosphere saturated with solvent vapor. Even though we find that evaporation exercises negligible influence for unentangled aqueous solutions, a closed cell is needed for volatile-entangled (VE) polymer solutions that display strong concentration-dependent change in rheology.…”

“…The choice of PEO solutions is motivated by three factors. First, the formation, morphology, and properties of PEO fibers are the focus of many fundamental studies. ,,,,,− Second, fibers formed by PEO alone, using PEO to enhance spinnability, or containing PEO blended with other polymers, particles, or proteins, are considered suitable for applications ranging from drug delivery, antimicrobial filters, battery separators, photovoltaics, and separation membranes. ,,,− Third, we have extensively characterized shear and extensional rheology response of aqueous PEO solutions, − and we recently showed that PEO fiber mats centrifugally spun with entangled PEO solutions in pure AcN rival crystallinity and mechanical properties of electrospun PEO fibers …”

“…We characterized the shear rheology response using torsional rheometry and identified the unentangled and entangled regimes by examining the concentration-dependent variation in zero shear viscosity. We obtained a measure of shear relaxation time from the onset of shear thinning and determined the extensional relaxation time using dripping-onto-substrate (DoS) rheometry. − ,, The magnitude and concentration-dependent variation of the measured extensional relaxation time, λ E is usually distinct from the shear relaxation time, due to the role of stretched chain hydrodynamics. − ,− The response to extensional deformations is relevant for fiber spinning and jetting or spraying applications. We opted for closed-cell DoS rheometry to minimize evaporation, as volatile-entangled (VE) polymer solutions exhibit substantial concentration-dependent variation in rheology.…”