Viscoelastic Properties of Polyacrylamide Nanocomposite Hydrogels Prepared in Electrolyte Media: Effect of Gelant Volume

In this work, nanocomposite (NC) hydrogels based on polyacrylamide/chromium triacetate were prepared at different reaction mixture (gelant) volumes and their crosslinking process and viscoelastic behaviors were studied. The X-ray diffraction (XRD) patterns taken from the NC hydrogels containing laponite nanoparticles did not show any distinct characteristic basal reflection for all of the NC hydrogels. Evaluating the crosslinking behavior of the gelants revealed that the torque value of the gelation increased with increasing the gelant volume. In addition, four successive steps in the gelation behavior were identified. According to the dynamic rheometry analysis of the prepared hydrogels, the storage modulus plateau range and its value decreased with increasing the gelant volume. Shear thinning behaviors were seen for all of the prepared gels. However, the gels prepared at larger gelant volumes showed a lower viscosity. The elastic properties of the NC gel were higher than that of the conventional gel. However, the addition of the laponite nanoparticles into the polyacrylamide gelling system slightly decreased the viscous energy dissipating and damping properties

Improved rheology and high-temperature stability of hydrolyzed polyacrylamide using graphene oxide nanosheet

Hydrolyzed polyacrylamide (HPAM) is a polymer that extensively used in chemical industry and hydrocarbon extraction and refinery processes, but suffers a common problem of high-temperature instability. This study improved high-temperature rheological characteristics of HPAM by using novel graphene oxide (GO) nanosheets. Stable GO dispersions in aqueous HPAM were formulated, and their dynamic and viscoelastic behaviors were studied. The results showed that the addition of GO significantly increased the viscosities and high-temperature stability of the base polymer fluid, as well as the elastic properties of the dispersion. Spectral data indicated the formation of covalent linkages and electrostatic hydrogen bonding between the GO and the HPAM functional groups, leading to enhanced stability and viscosity that is beneficial for high-temperature oil recovery. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47582

Study of polyacrylamide-surfactant system on the water–oil interface properties and rheological properties for EOR

Nowadays, due to the remarkable oil reduction in oil fields, enhanced oil recovery (EOR) techniques have been considered by a large number of scientists and company. Situ oil extraction is normally done by these techniques with high efficiency. In this particular study, five different surface active agents (surfactant), two kinds of oil with various API, two kinds of sulfonated polyacrylamide, two different electrolyte solutions with various TDS and two distinctive alcohols were tested and evaluated. An optimal formulation in terms of the properties and quantity of materials has to be used in order to enhance oil recovery, achieved by investigation of surface tension and the phase behavior of mentioned substances. Rheological behavior of polymer flooding and surfactant was studied. Employing this formulation, the maximum micro emulsion of oil in water occurred. Due to the synergy between surfactant and alcohol (as a co-surfactant), relatively lower amounts of surfactants were used which led to the dip in the cost of operation, and ultimately the efficiency of operation improved