Recent developments in membrane-based technologies for co2 capture

Rheology and applications of highly filled polymers: A review of current understanding

Rheology of corn stover slurries at high solids concentrations--effects of saccharification and particle size.

High solid dispersions are soft materials made of colloidal or non-colloidal particles dispersed at high volume fractions in a liquid matrix. They include hard sphere glasses, colloidal pastes, concentrated emulsions, foams, and vesicles. These materials are prone to exhibit different kinds of flow heterogeneities: shear banding, wall slip, and fracture. While wall slip is often considered as a nuisance by experimentalists, it appears to be a fundamental component to the way that high solid dispersions respond to mechanical deformation. Moreover, the ability of soft materials to slip onto surfaces allows them to move readily and efficiently in many natural phenomena and industrial processes. This review surveys recent developments and current research in the field. Topics like wall slip detection and control, microscopic modeling for rigid and soft particles materials, and the relation between wall slip and other flow heterogeneities are discussed. We also identify important open issues for future research.

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A review on wall slip in high solid dispersions

A highly permeable mixed matrix membrane containing CAU-1-NH2 for H2 and CO2 separation

For especially highly concentrated suspensions, slip at the wall is the controlling phenomenon of their rheological behavior. Upon correction for slip at the wall, concentrated suspensions were observed to have non-Newtonian behavior. In this study, to determine the true rheological behavior of model concentrated suspensions, “multiple gap separation method” was applied using a parallel-disk rheometer. The model suspensions studied were polymethyl methacrylate particles having average particle sizes, in the range of 37–231 μm, in hydroxyl terminated polybutadiene. The effects of particle size and solid particle volume fraction on the wall slip and the true viscosity of model concentrated suspensions were investigated. It is observed that, as the volume fraction of particles increased, the wall slip velocity and the viscosity corrected for slip effects also increased. In addition, for model suspensions in which the solid volume fraction was ≥81% of the maximum packing fraction, non-Newtonian behavior was observed upon wall slip correction. On the other hand, as the particle size increased, the wall slip velocity was observed to increase and the true viscosity was observed to decrease. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 439–448, 2005

Effect of volume fraction and particle size on wall slip in flow of polymeric suspensions

Permeabilities of N2, Ar, O2, CO2, and H2 gases in PEMA (Polyethylmethacrylate) membranes have been measured above and below glass transition in the temperature range of 25–70 °C. The permeabilities of the gases were observed increasing with temperature. Arrhenius plot of permeability versus temperature data showed that there is a slope discontinuity at near to Tg of PEMA. In addition, the effects of membrane preparation parameters by solvent casting method (percentage of polymer in solvent, annealing temperature, annealing time, evaporation temperature, and evaporation time) have been investigated by using homogenous dense membranes of PEMA. It is observed that membrane preparation parameters strongly affect the membrane performance and the reproducibility of the permeability measurements. On the other hand, the effect of polymer structure on membrane performance has been investigated. Comparison of the permeabilities of N2, Ar, O2, CO2, and H2 gases in PEMA and PMMA membranes shows that PMMA membranes have smaller permeabilities and higher selectivities than PEMA membranes because of their higher glass transition temperature, Tg. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3025–3033, 2007

Effect of temperature and membrane preparation parameters on gas permeation properties of polymethacrylates

Recent studies on polyethylene, elastomers, and thermoplastics have revealed that the construction material and surface roughness are two important factors affecting wall slip. In this study, to determine the true rheological behavior of model concentrated suspensions, a multiple-gap separation method was used in a parallel disk rheometer. The model suspensions studied were poly (methyl methacrylate) particles with an average particle size of 121.2 μm in hydroxyl-terminated polybutadiene. The aim of this study was to investigate the effect of disk Ra in the range of 0.49–1.51 μm and disk construction material on the wall slip and the true viscosity of the model concentrated suspensions. The wall slip velocity and the viscosity were found to be independent of Ra for particle size-to-disk Ra ratios of 80–247. Also, the true viscosity was found not to be affected by the rheometer surface construction material. Glass surfaces resulted in the highest slip velocity, whereas aluminum surfaces resulted in the lowest slip velocity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3341–3347, 2007

Sergul Acikalin Gulmus

Papers

Effect of volume fraction and particle size on wall slip in flow of polymeric suspensions

Effect of temperature and membrane preparation parameters on gas permeation properties of polymethacrylates

Effect of the surface roughness and construction material on wall slip in the flow of concentrated suspensions