Experimental and theoretical study of dilute polyacrylamide solutions: effect of salt concentration

Chen, Panke; Lin, Yao; Liu, Yanyan; Luo, Jia; Zhou, Guorong; Jiang, Bo

doi:10.1007/s00894-011-1332-9

Cited by 51 publications

(22 citation statements)

References 29 publications

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“…As salt is added, the repulsive interactions are screened and HPAM molecules become more flexible, i.e. their radius of gyration decreases (Chen et al 2012;Zhang et al 2008). In order to investigate the influence of polymer conformation on the curtain flow, we use aqueous solutions of fixed polymer concentration [HPAM] = 0.1 wt% and various salt concentrations [NaCl] ranging between 0 and 10 wt%.…”

Section: Polymers and Preparation Of The Solutionsmentioning

confidence: 99%

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Viscoelastic liquid curtains: experimental results on the flow of a falling sheet of polymer solution

et al. 2019

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We experimentally investigate the extensional flow of a sheet – or curtain – of viscoelastic liquid falling freely from a slot at constant flow rate under gravity. Extruded liquids are aqueous solutions of flexible polyethylene oxide (PEO) and of semi-rigid partially hydrolysed polyacrylamide (HPAM) with low shear viscosities. Velocimetry measurements reveal that the mean velocity field $U(z)$ (where $z$ is the distance from the slot exit) does not reduce to a free fall. More precisely, we show that the liquid falls initially with sub-gravitational accelerations up to a distance from the slot which scales as $g\unicode[STIX]{x1D70F}_{fil}^{2}$ (where $g$ is gravity and $\unicode[STIX]{x1D70F}_{fil}$ is the extensional relaxation time of the liquid) due to the stretching of polymer molecules. Beyond this elastic length, inertia dominates and the local acceleration reaches the asymptotic free-fall value $g$ . The length of the sub-gravitational part of the curtain is shown to be much larger than the equivalent viscous length $((4\unicode[STIX]{x1D702}/\unicode[STIX]{x1D70C})^{2}/g)^{1/3}$ for Newtonian liquids of density $\unicode[STIX]{x1D70C}$ and dynamic viscosity $\unicode[STIX]{x1D702}$ which is usually small compared to the curtain length. By analogy with Newtonian curtains, we show that the velocity field $U(z)$ rescales on a master curve. Besides, the flow is shown to be only weakly affected by the history of polymer deformations in the die upstream of the curtain. Furthermore, investigations on the curtain stability reveal that polymer addition reduces the minimum flow rate required to maintain a continuous sheet of liquid.

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Section: Polymers and Preparation Of The Solutionsmentioning

confidence: 99%

“…Indeed, since adding salt reduces the radius of gyration of the HPAM chains, polymers are less entangled, resulting in lower normal stresses. In other words, the critical overlap concentration increases when adding salt (Chen et al 2012;Zhang et al 2008). The data are fitted with a power law…”

Section: -4mentioning

confidence: 99%

Viscoelastic liquid curtains: experimental results on the flow of a falling sheet of polymer solution

et al. 2019

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“…The presence of salt, then, would both decrease effective surface charge and decrease the extent of aggregation, which is exactly what is seen in Figures 2 and S2. (Salt concentration may also influence polyacrylamide graft conformation in solution [35,36], but these effects have been neglected in our analysis.) If true, this would also imply that the aggregated clusters are only weakly aggregated.…”

Section: Particle Behaviormentioning

confidence: 99%

Tunable Pickering emulsions with polymer-grafted lignin nanoparticles (PGLNs)

Silmore

Gupta

Washburn

2016

Journal of Colloid and Interface Science

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Lignin is an abundant biopolymer that has native interfacial functions but aggregates strongly in aqueous media. Polyacrylamide was grafted onto kraft lignin nanoparticles using reversible addition-fragmentation chain transfer (RAFT) chemistry to form polymer-grafted lignin nanoparticles (PGLNs) that tune aggregation strength while retaining interfacial activities in forming Pickering emulsions. Polymer graft density on the particle surface, ionic strength, and initial water and cyclohexane volume fractions were varied and found to have profound effects on emulsion characteristics, including emulsion volume fraction, droplet size, and particle interfacial concentration that were attributed to changes in lignin aggregation and hydrophobic interactions. In particular, salt concentration was found to have a significant effect on aggregation, zeta potential, and interfacial tension, which was attributed to changes in solubility of both the kraft lignin and the polyacrylamide grafts. Dynamic light scattering, UV-vis spectroscopy, optical microscopy, and tensiometry were used to quantify emulsion properties and nanoparticle behavior. Under all conditions, the emulsions exhibited relatively fast creaming but were stable against coalescence and Ostwald ripening for a period of months. All emulsions were also oil-in-water (o/w) emulsions, as predicted by the Bancroft rule, and no catastrophic phase inversions were observed for any nanoparticle compositions. We conclude that lower grafting density of polyacrylamide on a lignin core resulted in high levels of interfacial activity, as characterized by higher concentration at the water-cyclohexane interface with a corresponding decrease in interfacial tension. These results indicate that the interfacial properties of polymer-grafted lignin nanoparticles are primarily due to the native hydrophobic interactions of the lignin core. These results suggest that the forces that drive aggregation are also correlated with interfacial activities, and polymer-nanoparticle interactions are critical for optimizing interfacial activities. Controlled radical polymerization is a powerful tool for polymer grafting that can leverage the intrinsic interfacial functions of lignin for the formation of Pickering emulsions.

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“…As the salt content increases, the double electrical layer on the polymer molecular chains are compressed and the electrostatic repulsion among the anions is shielded, decreasing the hydrodynamic radius of the polymer molecules [26][27][28].…”

Section: Effect Of Salinitymentioning

confidence: 99%

Study of adsorptive behavior of sulfonated polyacrylamide onto carbonate rock particles to enhance oil recovery

Sodeifian

Daroughegi

Aalaie

2015

Korean J. Chem. Eng.

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The adsorption of sulfonated polyacrylamide (SPAM) as an enhanced oil recovery polymer onto carbonate rock particles was studied using UV-visible spectroscopy. The effect of the experimental parameters of polymer concentration, salinity and temperature was investigated. The results showed that polymer adsorption increased as the SPAM concentration increased, but decreased as temperature and water salinity increased. Adsorption of the polymer in the presence of the anionic surfactant sodium lauryl ether sulfate (SLES) was evaluated in electrolyte media and in pure water. The adsorption equilibrium data for SPAM in electrolyte media was better fitted to the Langmuir isotherm than the Freundlich model. The thermodynamic parameters indicated that adsorption is a spontaneous and exothermic physisorption process.

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Experimental and theoretical study of dilute polyacrylamide solutions: effect of salt concentration

Cited by 51 publications

References 29 publications

Viscoelastic liquid curtains: experimental results on the flow of a falling sheet of polymer solution

Viscoelastic liquid curtains: experimental results on the flow of a falling sheet of polymer solution

Tunable Pickering emulsions with polymer-grafted lignin nanoparticles (PGLNs)

Study of adsorptive behavior of sulfonated polyacrylamide onto carbonate rock particles to enhance oil recovery

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