Rheology of fumed silica nanoparticles/partially hydrolyzed polyacrylamide aqueous solutions under small and large amplitude oscillatory shear deformations

Abstract

Partially hydrolyzed polyacrylamide (HPAM) is one of the most widely used polymers for enhanced oil recovery operations. However, high temperature and high salinity in oil reservoirs restrict its functionality and performance. To alleviate this, incorporating fumed silica nanoparticles (NPs) in HPAM solutions was found to be very effective in harsh oil reservoir conditions to improve the efficiency of polymer flooding. Studying the flow behavior of hybrid polymer and fumed silica NP solutions under real reservoir conditions can be very challenging and hard to achieve due to continuously converging and diverging flow through porous structures. In this regard, rheological analysis of such systems under well-controlled flow histories within the capability of rotational rheometers can be of great importance to fully understand the mechanical response of these hybrid solution systems. In this study, two types of fumed silica NPs with different surface chemistries and two types of HPAM polymers with different molecular weights were dispersed/dissolved in deionized water. Linear viscoelastic properties of the hybrid solution systems were studied based on their step-stress (creep) and small amplitude oscillatory shear responses. As deformation in porous media can be rapid and large, consideration of nonlinear viscoelastic properties can be very crucial. The stress decomposition method and Lissajous–Bowditch curves were used to describe the intercycle and intracycle shear-thickening and strain-stiffening ratios quantitatively and qualitatively. In brief, linear and nonlinear rheology conjugated with thermogravimetric analysis and cryo-scanning electron microscopy imaging enabled us to characterize viscoelastic properties of the hybrid systems and link our observations to microstructural features. Through polymer bridging, the slightly hydrophobic fumed silica NPs (AEROSIL R816) had a unique ability to form interconnected, predominately elastic network structures in contrast to large agglomerated structures formed by highly hydrophilic AEROSIL 300. This has led to observing very different rheological behaviors, regardless of the HPAM polymer molecular weight, below and above a critical fumed silica NPs concentration.

Development and Characterization of Stable Polymer Formulations for Manufacturing Magnetic Composites

“…Oscillatory frequency sweeps have been widely used to characterize polymer filled samples (polymer composites, polymer solutions, etc.) [34,35]. Information about a sample's rigidity and network structure can be obtained by studying viscoelastic parameters, such as the storage modulus (G'), loss modulus (G'') and damping factor (tan δ) [36].…”

Structural Characterization of CVD Custom-Synthesized Carbon Nanotube/Polymer Nanocomposites in Large-Amplitude Oscillatory Shear (LAOS) Mode: Effect of Dispersion Characteristics in Confined Geometries

“…Additionally, as the strain amplitude and frequency can be controlled independently, LAOS flow covers a wide spectrum of nonlinear situations with respect to time and deformation. 17,18 Considering the aforementioned reasons, over the past decade, LAOS has been extensively employed to study nonlinear viscoelasticity to detect any changes in topology, morphology, concentration, and so forth in a variety of systems, such as polymer solutions, 19,20 polymer nanocomposites, 21 and polymer hydrogels. 22 The LAOS approach provides an extensive framework to detect intracycle nonlinearities, providing vital information for the structure−property relationship of the filler−polymer systems.…”

X‐band dielectric properties of hybrid nanocomposites of nitrogen‐doped carbon nanotube/functionalized nanoclay/polyvinylidene fluoride nanocomposite

“…Moreover, based on the strain sweep test data (see Figure 11D), the order of the critical strain amplitude γ c (strain at which linear to nonlinear transition occurs, see the arrows in Figure 11D) of the samples is as follow: γ c,PVDF/clay > γ c,PVDF/clay/CNT > γ c,PVDF/CNT . In our previous works, [ 72‐76 ] we demonstrated that the stronger the nanofillers' network, the smaller γ c . Hence, the rigid network structure of the binary PVDF/N‐CNT nanocomposite is more sensitive to the applied deformation.…”