Polyacrylamide In Water Research Articles

Impact of hydrolysis on the quantification of sulfonated acrylamide copolymers by size exclusion chromatography with UV detection

AbstractSize exclusion chromatography with UV detection (SEC‐UV) is a precise method for quantifying polyacrylamides in water. However, its accuracy can be compromised in complex matrices due to chemical degradation of the polymer. This study focuses on the impact of hydrolysis on quantifying sulfonated polyacrylamide copolymers (PAM‐AMPS) via SEC‐UV, analyzing key influencing factors. Using controlled hydrolysis, hydrolyzed copolymer (HPAM‐AMPS) standards with varying hydrolysis degree (HD) (HD = 7%–33%) were prepared without significant changes in polymer chain size. SEC‐UV analysis revealed that quantification accuracy is highly dependent on hydrolysis extent. Errors are minimal for HD up to 10%, but significantly higher for HDs of 22%–33%. Furthermore, this effect is modulated by polymer concentration. Our findings indicate that there are two compensating factors for the decrease in molar absorptivity due to amide‐to‐carboxylate substitution: the sulfonate group acting as an additional chromophore, and a redshift in absorption spectra due to hydrogen bonding at higher concentrations. This interplay between HD and concentration in this type of sulfonated polyacrylamide can help reduce quantification errors in complex aqueous samples prone to chemical degradation, like those found in environmental and subsurface applications.

Demulsification law of polyether demulsifier for W/O crude oil emulsion containing hydrophobically modified polyacrylamide in water

Hydrophobically modified polyacrylamide (HMPAM) is one of the commonly used polymers for polymer flooding. Because it is water soluble, there are many reports on the impact of HMPAM on the stability and treatment of produced water (it is O/W emulsion), but few reports on its influence on the demulsification of W/O crude oil emulsion. In this paper, firstly, three types of HMPAM containing cationic, anionic, and nonionic hydrophobic monomers (abbreviated as P(AM-AANa-N)Cn, P(AM-AANA-S)Cn, and P(AM-AANA-O)Cn, respectively) were synthesized; Then, demulsification experiments and interface behavior experiments (including dynamic interfacial tension, dilatational rheology and dynamic coalescence time measurement) were conducted to investigate the influence of HMPAM on the demulsification performance of a W/O heavy oil emulsion demulsifier D1. The demulsification results showed that HMPAM reduced the dehydration speed of D1, the type of hydrophobic monomer and the length of hydrophobic chain in HMPAM can affect the final water separated of D1. P(AM-AANa-S)Cn, P(AM-AANa-N)Cn with long hydrophobic chain, and P(AM-AANa-O)Cn with short hydrophobic chains had the negative effect on performance of D1. The results of dynamic interfacial tension experiments indirectly showed that HMPAM had the influence on the D1′s conformation and speed of rearrangement at the W/O interface during the water droplet coalescence process, thereby affecting the reduction of elastic modulus (G′) of W/O interface and the coalescence rate of water droplets. When there was HMPAM in water, the coalescence time of water droplets increased, resulting in the decrease of dehydration rate. At the meantime, HMPAM had an impact on the lg(G1′/Gdemulsifier′)/lgG1′, thereby affecting the final water separated of D1.

Onset of transition in the flow of polymer solutions through deformable tubes

Experiments are performed to investigate laminar-turbulent transition in the flow of Newtonian and viscoelastic fluids in soft-walled microtubes of diameter ∼400 μm by using the micro-particle image velocimetry technique. The Newtonian fluids used are water and water-glycerine mixtures, while the polymer solutions used are prepared by dissolving polyacrylamide in water. Using different tube diameters, elastic moduli of the tube wall, and polymer concentrations, we probe a wide range of dimensionless wall elasticity parameter Σ and dimensionless fluid elasticity number E. Here, Σ = (ρGR2)/η2, where ρ is the fluid density, G is the shear modulus of the soft wall, R is the radius of the tube, and η is the solution viscosity. The elasticity of the polymer solution is characterized by E = (λη0)/R2ρ, where λ is the zero-shear relaxation time, η0 is the zero-shear viscosity, ρ is the solution density, and R is the tube radius. The onset of transition is detected by a shift in the ratio of centerline peak to average velocity. A jump in the normalized centerline velocity fluctuations and the flattening of the velocity profile are also used to corroborate the onset of instability. Transition for the flow of Newtonian fluid through deformable tubes (of shear modulus ∼50 kPa) is observed at a transition Reynolds number of Ret ∼ 700, which is much lower than Ret ∼ 2000 for a rigid tube. For tubes of lowest shear modulus ∼30 kPa, Ret for Newtonian fluid is as low as 250. For the flow of polymer solutions in a deformable tube (of shear modulus ∼50 kPa), Ret ∼ 100, which is much lower than that for Newtonian flow in a deformable tube with the same shear modulus, indicating a destabilizing effect of polymer elasticity on the transition already present for Newtonian fluids. Conversely, we also find instances where flow of a polymer solution in a rigid tube is stable, but wall elasticity destabilizes the flow in a deformable tube. The jump in normalized velocity fluctuations for the flow of both Newtonian and polymer solutions in soft-walled tubes is much gentler compared to that for Newtonian transition in rigid tubes. Hence, the mechanism underlying the soft-wall transition for the flow of both Newtonian fluids and polymer solutions could be very different as compared to the transition of Newtonian flows in rigid pipes. When Ret is plotted with the wall elasticity parameter Σ for different moduli of the tube wall, by taking Newtonian fluids of different viscosities and polymer solutions of different concentrations, we observed a data collapse, with Ret following a scaling relation of Ret ∼ Σ0.7. Thus, both fluid elasticity and wall elasticity combine to trigger a transition at Re as low as 100 in the flow of polymer solutions through deformable tubes.

IMMOBILIZATION OF COBALT DISULFOPHTHALOCYANINATE ONTO POLYMETHYLOLACRYLAMIDE

Different character of usage the porphyrins and their analogs immobilized on carrier polymers stimulates an increased interest in the synthesis and research of physico-chemical properties of porphyrin-polymer immobilizates. In this paper the peculiarities of a synthesis of water-soluble polymer systems containing cobalt disulfophthalocyaninate with the components of a different ratio are described. The methylolation reaction of polyacrylamide to immobilize cobalt disulfophthalocyaninate onto water-soluble carrier polymer has been carried out. It is known that heating polymethylolacrylamide or its solutions leads to the formation of three-dimensional structures with ether and methylene bridges. Therefore, initially the conditions for the preparation of polymethylolacrylamide with preservation of its water solubility were selected. It was found to obtain a water-soluble polymethylolacrylamide, it is necessary that the initial concentration of polyacrylamide in water did not exceed 2% by weight. The immobilization of phthalocyanine metal complex onto the modified polyacrylamide was carried out in two ways. The first is the interaction of the phthalocyanine metal complex with methylated polyacrylamide. The second is functionalization of polyacrylamide and the immobilization of phthalocyaninate metal complex onto the polymer in one-step. The introduction conditions of the cobalt disulfophthalocyaninate introduced influenced the formation of cross-linked structures in the synthesized samples. The introduction of macroheterocycle as a powder was found to promote the formation of insoluble compounds in aqueous media. Therefore, phthalocyanine metal complex was introduced into the system as 1% aqueous solution. The immobilization of the phthalocyanine metal complex onto a carrier polymer has been realized through the formation of hydrogen bonds between the methylol groups of polymethylolacrylamide and sulfo groups of the phthalocyanine metal complex and it was due to coordination interaction between the functional groups of the polymer and metallophthalocyanine as well. The amount of bound cobalt disulfophthalocyanine in the samples was determined by the electronic absorption spectra of the solutions of immobilized phthalocyanine metal complex onto the polymer. The mass content of immobilized cobalt disulfophthalocyaninate onto the polymer in the samples obtained by one-step is greater than in case of the samples obtained in two steps, the ratio of the initial reagents being the same.

Association behaviors of carbazole-labeled polyacrylamide in water studied by fluorescence spectroscopy

Spectroscopic signatures in aggregation process of carbazole-labeled copolymers in water.

Dynamic contact angle measurements of viscoelastic fluids

In this study, the dynamic contact angles of a series of viscoelastic fluids were measured through a modified Wilhelmy plate technique. The advancing and receding contact angles were measured by immersing and withdrawing a PTFE (Teflon) Wilhelmy plate from a reservoir containing a series of different Newtonian and viscoelastic test fluids. The viscoelastic fluids that were tested consisted of either solutions of polyethylene oxide or polyacrylamide in water where the concentration of the polymer was varied to produce solutions with different amounts of fluid elasticity with and without shear thinning. The advancing contact angles of all the viscoelastic fluids tested were found to increase with increasing plate velocity. Conversely, the receding contact angles in each case were found to decrease with increasing contact line velocity. A number of previous measurements have been performed for shear thinning fluids. The measurements presented here are the first to probe the response of the dynamic contact angle at large Weissenberg numbers where the elasticity of the liquid becomes important. For fluids with increased fluid elasticity, the onset of the variation of receding contact angles was found to be delayed to higher contact line velocities and capillary numbers. It was also found that, unlike the case of Newtonian fluids, the cube of advancing and the cube of the receding contact angles were both found to be proportional to the square of the capillary number for highly elastic fluids. Finally, a simple model was proposed to account for the role of elasticity and shear thinning of the viscosity on the dynamic contact angle.

Heat Transfer of Dilute Polyacrylamide Solutions in Flattened Tube Exchangers

Heat transfer studies of dilute viscoelastic liquids in four flattened tubes with 0.635 cm original diameter, about 173 cm long, and with aspect ratios ranging from 1.4 to 5.7 were conducted. Hot water was used as the heating medium, and dilute solutions of polyacrylamide in water and in water mixtures were used as the viscoelastic solutions. Flattening the tubes could increase heat transfer by 101%, while secondary flow could further increase heat transfer coefficient by 75% at an aspect ratio of 1.6. Greater polyacrylamide concentrations increased heat transfer performance marginally. Viscosity does not influence the formation of secondary flow.

Thermoresponsive fluorinated polyacrylamides with low cytotoxicity

We report the unique thermoresponsive properties of fluorinated polyacrylamides, poly[N-(2,2-difluoroethyl)acrylamide] (P2F). The solubility of fluorinated polyacrylamides in water can be easily controlled by changing the number of fluorine atoms in N-ethyl groups. Moreover, we demonstrate that fluorinated polyacrylamides are less cytotoxic than poly(N-isopropylacrylamide) (PNIPAM).

Study on Synthesis of Cationic Water in Water Polyacrylamide Emulsion Strength Agent

Emulsion copolymerization of acrylamide (AM) and cationic monomer DMC (methyl acrylacyl oxyethyl trimethyl ammonium chloride) was studied. A series of cationic polyacrylamide (CPAM) emulsion were synthesized using Water in water emulsion polymerization. Influence of polymerization conditions such as cationic monomer (DMC) ratio, reaction time, the initiator dosage on synthetic product strengthening effect to paper pulp was studied. It was showed that the CPAM emulsion optimal synthetic conditions was that AM monomer second adding amount was 60% AM total amount, ammonium persulfate initiator and sodium hydrogen sulfite initiator dosage was 0.138g and 0.03g respectively, mass ratio of DMC and AM was 15:85, reaction time was 7 hours. When the dosage of CPAM emulsion was 1.0% to absolute dry bleached wheat straw pulp, distinct strengthening effect was acquired, tensile index and tearing index of handsheet was increased by 27.2% and 26.8% respectively.

Investigations of vortex formation in microbifurcations

The paper is dedicated to experimental studies and numerical simulations of viscous and viscoelastic flows in microchannels. The present work investigates separation phenomena and the formation of vortical structures in two microbifurcations with one closed branch: (1) Y-bifurcation with a square cross section and (2) T-bifurcation with trapezoidal sections and small aspect ratios depth/width. The main goal of the study is to characterize the dynamics of the vortex from the vicinity of Y-bifurcation and to emphasize the changes induced by the presence of elasticity on the local path lines. Velocity measurements and flow pattern visualizations of Newtonian fluid (deionized water) and weakly elastic polymer solution (low concentration of polyacrylamide in water) are obtained using a μPIV system. Numerical computations are performed in 2D and 3D flow configurations with the commercial FLUENT code. The Newtonian simulations offer very precise descriptions of the vortical structures for all flow regimes. In the case of polymer solution, the comparison between experimental data and numerical solutions for generalized Newtonian models prove the dominant role of elasticity in modifications induced on the vortical patterns in the analyzed microgeometries. The present topic is of great interest in developing novel microfluidic applications which require precise control of the hydrodynamics of viscoelastic fluids in the vicinity of complex geometries and patterned surfaces.

Laminar flow heat transfer of dilute viscoelastic solutions in flattened tube heat exchangers

Abstract Heat transfer studies of non-Newtonian liquids in non-circular exchangers are not many, and much less on viscoelastic liquids in flattened tubes. Heat transfer studies of dilute viscoelastic liquids in flattened tubes with 0.635 cm and 1.27 cm original diameters and 50 cm–76 cm lengths and aspect ratios ranging from 1.4 to 5.7 were carried out. Five flattened tube heat exchangers with four thermocouples soldered at regular intervals on the outside wall were placed in turn in the experimental circuit to determine the heat transfer coefficients. Hot water was used as the heating medium; and dilute solutions of polyacrylamide in water and in water/glycerol mixtures were used as the viscoelastic solutions. Heat transfer increase as a result of flattening the tubes could be 101% higher while the effect due to secondary flow had a maximum additional increase compared to that for water of 40% for the 250 ppm solution at an aspect ratio of 1.6. Corresponding values for the 500 ppm solutions in water and in water/glycerol mixture were about 53% and 55% respectively at an aspect ratio of 1.8. Increased polymer concentration had only a marginal effect on heat transfer performance.

A Practical Method for Synthesis of Stable Phosphorus Ylides in the Presence of Polyacrylamide in Aqueous Media

Stable crystalline phosphorus ylides were obtained in good to excellent yields from the 1:1:1 addition reaction between triphenylphosphine, dialkyl acetylenedicarboxylates and β -dicarbonyl or heterocyclic compounds such as, diethyl malonate, acetyl acetone, 1, 3-dimethylbarbituric acid, meldrum's acid, 2-benzoxazolinone, pyrrole-2-carboxaldehyde, benzotriazole, 5-methyl benzotriazole, and 5-chloro benzotriazole, in the presence of polyacrylamide in water. The green and mild reaction conditions, medium to short reaction time, low cost, ready preparation are the main advantages of this method.

Thermodynamic Interactions in Double-Network Hydrogels

Double-network hydrogels (DN-gels) prepared from the combination of a moderately cross-linked anionic polyelectrolyte (PE) and an uncross-linked linear polymer solution (NP) exhibit mechanical properties such as fracture toughness that are intriguingly superior to that of their individual constituents. The scheme of double-network preparation, however, is not equally successful for all polyelectrolyte/neutral polymer pairs. A successful example is the combination of poly(2-acrylamido-2-methyl-1-propane sulfonic acid) (PAMPS) cross-linked network and linear polyacrylamide (PAAm), which results in DN-gels with fracture strength under compression approaching that of articular cartilage ( approximately 20 MPa). Small-angle neutron scattering was used to determine the thermodynamic interaction parameters for PAMPS and PAAm in water as a first step to elucidate the molecular origin responsible for this superior property. Measurements on PAMPS/PAAm DN-gels and their solution blend counterparts indicate that the two polymers interact favorably with each other while in water. This favorable PAMPS/PAAm interaction given by the condition chi(PE-NP) < chi(PE-water) <chi(NP-water), where chi is the Flory-Huggins interaction parameter, is consistent with some of the salient features of the DN structure revealed by SANS, and it may also contribute to the ultimate mechanical properties of DN-gels.

Molecular Interactions with Polyacrylamide in Ethanolamine, Diethanolamine, and Triethanolamine Solutions Measured Ultrasonically

The ultrasonic velocity and density of polyacrylamide in water, ethanolamine, diethanolamine, and triethanolamine solutions were measured at 299 K at different concentrations. Variations in ultrasonic velocity, acoustic impedance, adiabatic compressibility, and free length were found to be nonlinear. Other parameters, such as mole fraction, effective molecular weight, molar volume, Rao constant, Wada's constant, available volume, and relaxation strength were also calculated. The nonlinear variation predicts the presence of solute–solvent interactions in PAA solutions, and it is observed that the interactions are very weak in a particular concentration. The molecular interactions present in the solutions are discussed in light of polymer concentrations and solvents.

Stable Jets of Viscoelastic Fluids and Self-Assembled Cylindrical Capsules by Hydrodynamic Focusing

We demonstrate formation of long-lived cylindrical jets of a viscoelastic fluid using hydrodynamic focusing. A solution of polyacrylamide in water is driven coaxially with immiscible oil and subjected to strong extensional flow. At high flow rates, the aqueous phase forms jets that are 4-90 microm in diameter and several centimeters long. The liquid surfaces of these jets are then used as templates for assembly of microspheres into novel rigid and hollow cylinders.

Dilute solution behaviour of progressively hydrolyzed polyacrylamide in water– N, N dimethylformamide mixtures

The intrinsic viscosities [ η’s] of anionic (hydrolyzed; low and high carboxyl content) and nonionic polyacrylamide (unhydrolyzed) were measured in water– N, N dimethylformamide mixtures at various temperatures. Non-polyelectrolyte behavior of low carboxyl content polyacrylamide was observed in mixed solvent system. The plots of [ η] vs. solvent composition in a mixed solvent system pass through minima for both high as well as low carboxyl content polymers but through a maximum for nonionic polyacrylamide. Observed minimum for charged polymers may be attributed to the loss of polymer sites available to interact with solvent for H-bonding interaction between neighboring amide and the acid groups. The maximum for nonionic polymer at the particular solvent composition arises for the most powerful cosolvent effect. Existence of two antagonistic effects is apparent in [ η] values of nonionic polymer at various temperatures. Huggins constant ( K H) also indicates a significant variation of cosolvency as a function of solvent composition. Activation parameters of viscous flow were calculated using Frenkel–Eyring equation. The volume related parameter and the shape factor were also computed. Shape factor data indicate that polymer molecules are more or less rigid spheres and are not affected by temperature and composition of solvent.

Interactions of glucose and polyacrylamide in solutions and gels

AbstractThe swelling of polyacrylamide (PAAm) gels increased with rising glucose concentrations, and so did the osmotic pressure of the soluble polymer and its intrinsic viscosity. A Flory–Huggins‐based model for the osmotic pressure of a nonionic hydrophilic polymer in a ternary solution consisting of a main solvent, a polymer, and a nondissociating low‐molecular‐weight cosolute was developed and examined. The model‐calculated values were in reasonably good agreement with experimental results for the water–PAAm–glucose system studied when PAAm–water and glucose–water interaction coefficients from the binary systems were used, and only the PAAm–glucose interaction coefficient was adjusted. Its negative value suggested a favorable interaction of glucose and PAAm, supporting the notion of glucose being a good cosolvent for PAAm. Isothermal titration microcalorimetry results showed no evidence for the binding of glucose to PAAm, but an exothermic interaction was indicated between glucose and PAAm. Microcalorimetrically determined enthalpic contributions to the Flory–Huggins interaction coefficients showed enthalpically favorable binary interactions, particularly the enthalpic component of the PAAm–glucose interaction coefficient (χH23), which was slightly negative. The enthalpically favorable interaction between glucose and PAAm may explain the increased osmotic pressure of PAAm in glucose solutions. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3053–3063, 2003

Efficiency of methanol induced flocculation of AgI hydrosol stabilized by polyacrylamide

AgI hydrosol stabilized by polyacrylamide (PAAm) adsorbed from the dispersion medium was used in the studies. The efficiency of methanol induced flocculation of the system was examined at different polymer and electrolyte concentrations. Properties of PAAm in water–methanol–electrolyte mixtures were also examined using nephelometric and viscometric methods. Moreover, the solvent power of the medium for PAAm was concluded from experiments on the swelling of PAAm gel in media of different composition. Properties of AgI particles in the absence and in the presence of PAAm were deduced from their electrophoretic mobilities. The results obtained demonstrated the complex behavior of dispersions stabilized by polymer adsorbed from the solution. The important effect of free polymer concentration in the continuous phase on the dispersion properties was underlined. In particular, its effect on the reduction of efficiency of non-solvent induced flocculation is discussed.

Heterogeneous effects on the thermal and photoreactivities of tris(1,2-diaminoethane)chromium(III) cation and hexathiocyanatochromate(III) anion in aqueous media

The ground- and excited-state reactivities of the [Cr- (en)3]3+ (en=1,2-diaminoethane) and [Cr(NCS)6]3− ions in a polyacrylamide (PAA) environment are reported. The aquation kinetics of these complexes has been studied to identify the effect of added PAA with varying molecular weight. Aquation of the complexes in aqueous acid containing PAA yielded the respective substituted products. The macromolecule in solution was found to decrease significantly the rate of ligand replacement. Similarly, photolysis of the cationic and anionic complexes in water–PAA mixtures revealed a decrease in aquation quantum yield. Possible explanations for the decrease in reaction rates and quantum yields are discussed.

A Light-Scattering Study of the Aggregation Behavior of Fluorocarbon-Modified Polyacrylamides in Water

Fluorocarbon-modified polyacrylamide chains can form large multichain aggregates. The aggregation behavior of a series of fluorocarbon-modified polyacrylamides in water has been investigated by a combination of static and dynamic laser light scattering (LLS). The critical aggregation concentration (CAC) was estimated from the emergence of a second peak in the line-width distribution measured in dynamic LLS. Our results showed that CAC strongly depends on the amount of 2-(N-ethylperfluorooctanesulfonamido)ethyl acrylate (FX-13) copolymerized with polyacrylamide and also on the polymer concentration. When the FX-13 content is 0.227 mol %, CAC is as low as 1.34 × 10-4 g/mL, while when the FX-13 content is less than 0.028 mol %, no aggregation has been observed over the entire concentration range studied. A combination of the weight-average molecular weight from static LLS and the area ratio of the two peaks in the line-width distribution from dynamic LLS leads us to the estimation that on average each aggregate consists of ∼5−9 individual polymer chains for the acrylamide copolymer with 0.227 mol % FX-13. The solution contained 40 wt % of the multichain aggregates when the polymer concentration was higher than the CAC. On the other hand, the intensity ratio of the light scattered from the multichain aggregates over that from individual chains increased linearly with increasing polymer concentration.