Experimental investigation of enhancement of carbon dioxide foam stability, pore plugging, and oil recovery in the presence of silica nanoparticles

The influence of surface-modified silica (SiO₂) nanoparticles on the stability and pore plugging properties of foams in porous media was investigated in this study. The pore plugging ability of foams was estimated from the pressure drop induced during foam propagation in porous media. The results clearly showed that the modified SiO₂ nanoparticlestabilized foam exhibited high stability, and the differential pressure increased in porous media by as much as three times. The addition of SiO₂ nanoparticles to the foaming dispersions further mitigated the adverse effect of oil toward the foam pore plugging ability. Consequently, the oil recovery increased in the presence of nanoparticles by approximately 15% during the enhanced oil recovery experiment. The study suggested that the addition of surface-modified silica nanoparticles to the surfactant solution could considerably improve the conventional foam stability and pore plugging performance in porous media.     

Bulk and bubble-scale experimental studies of influence of nanoparticles on foam stability

Influence of silicon oxide(SiO_2) and aluminum oxide(Al_2O_3) nanoparticles on the stability of nanoparticles and sodium dodecyl sulfate(SDS) mixed solution foams was studied at bulk and bubble-scale. Foam apparent viscosity was also determined in Hele-Shaw cell In order to investigate the foam performance at static and dynamic conditions. Results show that the maximum adsorption of surfactant on the nanoparticles occurs at 3 wt% surfactant concentration. Foam stability increases while the foamability decreases with the increasing nanoparticle concentration. However, optimum nanoparticle concentration corresponding to maximum foam stability was obtained at 1.0 wt% nanoparticle concentration for the hydrophilic SiO_2/SDS and Al_2O_3/SDS foams. Foam performance was enhanced with increasing nanoparticles hydrophobicity. Air-foams were generally more stable than CO_2 foams.Foam apparent viscosity increased in the presence of nanoparticles from 20.34 mPa·s to 84.84 mPa·s while the film thickness increased from 27.5 μm to 136 μm. This study suggests that the static and dynamic stability of conventional foams could be improved with addition of appropriate concentration of nanoparticles into the surfactant solution. The nanoparticles improve foam stability by their adsorption and aggregation at the foam lamellae to increase film thickness and dilational viscoelasticity. This prevents liquid drainage and film thinning and improves foam stability both at the bulk and bubble scale.     

The Effect of the Structure of Clay and Clay Modifier on Polystyrene-Clay Nanocomposite Morphology: A Review

Nanocomposites formation brings about an enhancement of many properties for polymers. They have attracted interests since they attain significant properties with far less clay content. It is generally assumed that exfoliation nanocomposites are preferred for the greatest increases in properties, but that is not correct in flame retardency properties. In this paper the effects of different types of clays and clay modifiers on final morphology of PS/clay nanocomposites were reviewed. Clay charge density and length, bulk, polarity, functional groups and polymerizability of the clay modifier are very significant in their efficiency and final morphology of PS/Clay nanocomposite.     

Recursive Formalism with a Minimal Dynamic Parameterization for the Identification and Simulation of Multibody Systems. Application to the Human Body

This paper presents a multibody formalism using a minimal set of dynamicalparameters, based on the barycentric approach. Using relative jointcoordinates, we show that it is possible to generate recursively the inverseand direct dynamics in terms of this minimal set, rather than using theclassical ones (mass, centre of mass and inertia matrix). More thanproviding a very compact scheme in terms of flops, the proposed formalism,in which the independent dynamical parameters appear linearly, is a precioustool for identification purpose; indeed, the recursive nature of theformalism and its symbolic implementation allows us to deal with very large models, such as the human body for instance. The approach is then applied to the identification of some of the human body's dynamical parameters, on the basis of a trajectory issuing from a volleyball typical movement.