The Role of Surfactants in Mechanical Degradation of Drag-Reducing Polymers

Abstract

Turbulent drag reduction behavior of mixed polymer–surfactant systems (anionic polymer/cationic surfactant; nonionic polymer/cationic surfactant; nonionic polymer/anionic surfactant) was studied in a pipeline flow loop to explore the role of surfactants in mechanical degradation of polymers. The polymers investigated were nonionic polyethylene oxide (PEO) and anionic polyacrylamide (PAM). The surfactants studied were cationic octadecyltrimethylammonium chloride (OTAC) and anionic sodium dodecyl sulfate (SDS). The pipeline flow results obtained for PAM/OTAC mixtures support the idea that the coiling of polymer molecules does not protect the polymer molecules against shear degradation. The addition of oppositely charged cationic surfactant (OTAC) to anionic polymer (PAM) results in coiling of polymer molecules. The coiled polymer molecules undergo faster mechanical degradation than stretched polymer molecules. The addition of surfactant (cationic OTAC or anionic SDS) to nonionic polymer PEO increases the resistance of polymer molecules against shear degradation. This is reflected in the pipeline flow results. The effect is more significant for anionic surfactant (SDS) than for cationic surfactant (OTAC) especially at high concentrations of surfactant; the smaller size of the headgroup of anionic surfactant monomers allows them to have a greater influence on the polymer molecules. These results support the idea that extended polymer chains are more resistant to mechanical degradation as compared with coiled polymer molecules. The polymer chains undergo extension due to repulsion between the neighboring surfactant micelles attached to the backbone of the polymer chains.

Intensification of drag reduction effect by simultaneous addition of surfactant and high molecular polymer into the solvent

“…The effect of drag reduction of flow by high molecular polymer or surfactants has also some limitations which come from the properties of additives. The main disadvantage of high molecular polymers is their susceptibility to mechanical and thermal degradation (Kim et al, 2000;White and Mungal, 2008;Mohsenipour and Pal, 2013a). In case of surfactant solutions, it is a certain critical Reynolds number exceeding of which results in the loss of micelles orientation and the collapse of the DR effect (Wang et al, 2011).…”

“…In case of surfactant solutions, it is a certain critical Reynolds number exceeding of which results in the loss of micelles orientation and the collapse of the DR effect (Wang et al, 2011). The addition of surfactant to polymer solution effectively reduces polymer degradation process, especially when the flow temperature of the solution is high (Kim et al, 2000;Mohsenipour and Pal, 2013a). The phenomenon of the fluid flow drag reduction by simultaneous addition of the high molecular polymer and the surfactant with salt additives into the solvent is still a relatively new and poorly recognized issue.…”

Experimental studies on drag reduction by coupled addition of nonionic polymer poly(ethylene oxide) and cationic surfactant cetyltrimethyl ammonium chloride

“…The present investigations have shown that polymers or surfactants alone as the drag‐reducing agent have certain advantages and disadvantages due to their properties. For instance, polymers can induce the efficient drag reduction at a relatively low concentration, but they are susceptible to thermal or/and mechanical degradation at the intense shear or the high temperature . Such degradation is permanent and irreversible, which leads to lost in the drag reduction function.…”

“…Surprisingly, the injection of a certain surfactant into drag‐reducing solution of polymers alleviates the degradation of polymer molecular chains effectively. This is because surfactant micelles and polymer molecular chains interact to form new conformations helpful to improve the drag reduction efficacy . Accordingly, it is vital for obtaining a high and stable drag reduction rate to investigate the synergistic influence of polymers and surfactants on the drag reduction deeply.…”

Rheological Investigation of Wormlike Micelles Based on Gemini Surfactant in EG–Water Solution

“…WLM behave like linear polymer chains and can entangle into a tri-dimensional network, therefore imparting huge viscoelasticity to the solutions. Due to the desirable viscoelasticity, WLMs systems have found extensive applications as rheology control reagents in home and personal care, drag reduction [2], oil exploration, hydraulic fracturing, drug release [3], etc.…”