Cationic Acrylamide Copolymers Research Articles

Mechanistic aspects of nanocellulose–cationic starch–colloidal silica systems for papermaking

Optimization of a chemical additive program for a paper machine can require attention to both colloidal charges and kinetic effects. This work considered an additive program with two negatively charged substances (nanofibrillated cellulose [NFC] and colloidal silica) and two positively charged items (cationic starch and cationic acrylamide copolymer retention aid). Results were shown to depend on charge interactions; however, that clearly was not the whole story. Some findings related to cationic demand, dewatering, fine-particle retention, and flocculation among fibers were best explained in terms of at least partly irreversible complexation interactions between the charged entities. Adjustments in ratios between oppositely charged additives, their sequences of addition, and effects of hydrodynamic shear levels all affected the results. In general, the most promising results were obtained at a cationic starch level of 0.25% to 0.5% based on sheet solids in systems where the cationic starch was used as a pretreatment for NFC.

Self-Assembly Supramolecular Systems Based on Guanidinium Salts Modified Hyperbranched Polyamidoamine and Cationic Acrylamide Copolymers.

Herein, novel hyperbranched polyamidoamine guanidinium salts (GS-h-PAMAM) and two cationic acrylamide copolymers P(AM-DAC-ABSM) and P(AM-DAC-AMTU) were successfully prepared. Then, self-assembly supramolecular systems were synthesized by directly mixing GS-h-PAMAM with copolymers in aqueous solution, and the mechanism of the self-assembly process was speculated. FT-IR, NMR, and SEM were used for structural confirmation. Furthermore, the excellent solution properties revealed that the supramolecular systems had potential application in clay hydration inhibitors. More importantly, utilizing functionalized hyperbranched polyamidoamine in the synthesis self-assembly supramolecular systems was an effective strategy for expanding their application fields and developing new functional materials, providing a powerful reference for the next study.

Intact and broken cellulose nanocrystals as model nanoparticles to promote dewatering and fine-particle retention during papermaking

Cellulose nanocrystals (CNCs), either in intact form or after mechanical shortening, were used as a model nanoparticle for enhancement of dewatering and fine-particle retention during lab-scale papermaking process evaluations. Cryo-crushing, using dry or wet CNCs, was performed to shorten the particles from an initial mean value of 103.1 nm to either 80.4 nm (wet crushed) or 63.4 nm (dry crushed). Papermaking-related tests were performed with the solids from 100 % recycled copy paper, which were prepared as a 0.5 % solids suspension in dilute Na2SO4 solution and then treated successively with 0.05 % of poly-diallyldimethylammonium chloride, 0.05 % of very-high-mass cationic acrylamide copolymer, and then various types and dosages of negatively charged nanoparticles. The performance of the CNCs, relative to papermaking goals, was compared to that of two colloidal silica products that are widely used in industry for this purpose. All of the nanoparticles were observed to promote both dewatering and fine-particle retention. The intact CNCs were more effective than the broken CNCs with respect to fine-particle retention. Effects on flocculation of the fiber suspension were detectable, but not large relative to the sensitivity of the test employed. Results are discussed in the light of concepts of polyelectrolyte bridges and the participation of elongated nanoparticles in completing those bridges in such a way as to form shear-sensitive attachments among solids surfaces in the suspension.

Evaluation of the Flocculation and Reflocculation Performance of a System with Calcium Carbonate, Cationic Acrylamide Co-polymers, and Bentonite Microparticles

Flocculation, flocs resistance, and reflocculation capacity of a precipitated calcium carbonate (PCC) suspension with cationic polyacrylamides (C-PAMs) varying in charge density and degree of branching were investigated in previous studies and correlated with retention and drainage performance in papermaking. In this study, the reflocculation performance of the PCC suspension was investigated using the same C-PAMs, in combination with microparticles, since microparticle retention systems have been widely used in papermaking to improve reflocculation of the suspension. Moreover, flocculation and reflocculation performance evaluated using the laser diffraction spectroscopy (LDS) technique was compared with that obtained using focused-beam reflectance microscopy (FBRM) to monitor the process. The coupling of these two techniques allows a detailed analysis of the reflocculation process, including evaluation of the flocs structure before and after the reflocculation stage.

The effects of acrylamide polyelectrolytes on aquatic organisms: Relating toxicity to chain architecture

Understanding the inherent toxicity of water-soluble synthetic polyelectrolytes is critical for adequate risk management as well as enhancing product design when biological activity is a key performance index (e.g. for application in biofouling bivalves’ control). The toxicity of two cationic acrylamide copolymers with different chain branching degree was evaluated. Standard ecotoxicity tests were conducted with microalgae and daphnids. The susceptibility of Corbicula fluminea, as a biofouling bivalve, was also evaluated. The effect of polyelectrolyte on the test media viscosity and the polymer chain size distributions under the experimental conditions were also examined. The susceptibility of the microalgae to both polymers was similar. As the complexity and size of the test organisms increased, differences in toxicity due to different chain architecture were noticeable. The more branched polymer was significantly less toxic to both daphnids and the bivalves, which could be linked to the distinctive features of its bimodal size chain distribution. This architecture resulted in both more compact globular molecules and the formation of aggregates, which reduce the polymer interaction with the biological surfaces. The results of this study promote the incorporation of environmental considerations in polyelectrolyte development and contribute to the design of improved solutions for controlling biofouling bivalves.

Flocculation on nanohybrid polymer-inorganic nanosystems in gravity and centrifugal force fields

The kinetics of free and hindered sedimentation of a suspension of titanium dioxide (anatase) under the action of a high-molecular-weight cationic acrylamide copolymer and of hybrid polymer-inorganic nanosystems was studied. The influence of the content of the cationic acrylamide copolymer in hybrid systems and of the particle size on the TiO2 aggregation in gravity and centrifugal force fields was analyzed.

Effect of Branch Degree of Cationic Acrylamide Copolymers on Flocculation Properties

Three kinds of cationic acrylamide copolymer with different branch degree were prepared controlling the dosage of N, N’-methylenebisacrylamide. The physical characteristics of the branch-degree- modified copolymers were analyzed by intrinsic viscosity and charge density. The branch degree measurements were investigated by applying the colloidal titration phenomena using a spectrophotometer and comparison with the cationic regain measurement method. The results showed that the absorbance behaviors of spectrophotometer were distinctively different with the branch degree of copolymers. Also, the branch degree determinations and molecular structure estimations of the copolymers were numerically measured by applying the titration phenomena using a spectrophotometer. Finally, three kinds of branch-degree-modified copolymers were applied to flocculation test using arbocel micro pulp for the determination of flocculation behavior by different morphology of cationic acrylamide copolymers.

Flocculating Properties of Water-Soluble Polymer-Colloid Complexes of Aluminoxane Particles with Weakly Charged Cationic Polyelectrolytes

The flocculating properties of polymer-colloid complexes (PCCs) formed via noncovalent interactions of positively charged aluminoxane particles (APs) with macromolecules of weakly charged cationic acrylamide copolymers from the Praestol and Organopol series have been studied. The PCCs that spontaneously formed during mixing of sols of a high-basicity aluminum polyhydroxochloride (APHC) with aqueous solutions of the copolymers exhibit high flocculating ability under the conditions of gravity sedimentation of the model kaolin dispersion with Сd = 8 g/dm3, and their efficiency exceeds both that of the copolymers and the earlier obtained PCCs with nonionogenic polyacrylamide (PAA). In contrast to weakly charged polycationites, the fully charged KF-99 polyelectrolyte does not form PCCs and the products of its mixing with APHC do not reveal an increased flocculating effect.

Kinetic aspects of flocculation of bentonite clay in the presence of anionic and cationic acrylamide copolymers

The flocculation kinetics in aqueous-salt medium in the presence of anionic and cationic high-molecular-weight random acrylamide copolymers was studied in the hindered sedimentation mode, with a suspension of bentonite clay as example. The influence exerted on the flocculation parameters by the concentration and order of addition of ionic acrylamide copolymers taken in various combinations was analyzed.

Cationic acrylamide copolymers and terpolymers as flocculants for model aqueous suspensions

Summary — Cationic acrylamide copolymers with diallyldimethylammonium chloride and terpolymers of the both monomers with N-vinylformamide were synthesized, characterized by capillary viscometry and their flocculation efficiency evaluated by extinction, sludge volume and solid matter recovery measurements. The polymerization reactions were carried out either as thin-layer processes in aqueous solutions or as microsuspension polymerization. The results from the numerous flocculation tests performed on model aqueous suspensions of fine coal, colloidal silica and talc have been presented and discussed. Flocculation efficiency was determined taking into account the type and dose of the used copolymer.

Performance of four polyelectrolytes as flocculation aids in the primary treatment of textile effluents

Samples of textile effluents were subjected to physico-chemical treatment using alum, Polyaluminium Chloride (PAC), and different anionic and cationic acrylamide copolymers. Except for alum, all chemicals were tested individually. Combinations of alum and PAC with different anionic and cationic polyelectrolytes were also tested. Results indicated the anionic polyelectrolyte to be the best polymer when used in combination with inorganic coagulants. 30-40 mg/L PAC and 0.75 mg/L of anionic polymer resulted in the best removals of Chemical Oxygen Demand (COD), Total Suspended Solids (TSS) and Turbidity of 32.0-38.2%, 80.0-85.0% and 25.3-47.0%, respectively. This study indicated that dye-loaded textile wastewater could be treated with blends of inorganic?organic coagulants to reduce the organic load. However, the colour of the wastewater could not be removed.

Flocculation of the titanium dioxide suspension (anatase) with compositions from anionic and cationic acrylamide copolymers

We have studied the kinetics of flocculation in metered introduction into an aqueous-salt medium of compositions from acrylamide anionic and cationic copolymers in the mode of hindered precipitation on a model disperse system—a suspension of titanium dioxide of the anatase form. We have noted a strong relationship between the flocculating indicators and the intensity of selective contact between oppositely charged fragments of macromolecules of ionogenic polyacrylamide flocculants and as a result of it, from the mode of introduction into the disperse system of polymer components: simultaneously or sequentially.

Retention aid polymer interactions with cellulosic surfaces and suspensions: A review

Retention aids can be defined as very-high-mass, water-soluble polymers that are added to cellulosic fiber slurries before the formation of paper in order to improve the efficiency with which fine particles, including cellulosic fines, are retained in the paper product. Optimization of retention aid performance can be a key to achieving efficient and environmentally responsible papermaking objectives. This article reviews various published theories related to retention aid use. Findings related to three main classes of retention aid polymers are considered: cationic acrylamide copolymers (cPAM), anionic acrylamide copolymers (aPAM), and polyethylene oxide (PEO). While many aspects of the interactions of each of these classes of retention aid products can be understood based on colloid chemistry principles, further research is needed in order to more fully bridge the gap between theory and practice.

Production of Exploding Materials for Detonators: Control of Crystal Growth of Lead and Barium 2,4,6‐trinitroresorcinate

AbstractThe production of lead and barium 2,4,6‐trinitroresorcinate in a suitable form for loading by gravity in detonator production has been investigated. During the work, we discovered that the synthesis of the mentioned salts in the presence of some crystal habit additives gives such characteristics of the products. A goal of our work was to investigate the role of some crystal growth additives in the nucleation, growth, size, and shape of lead 2,4,6‐trinitroresorcinate and barium 2,4,6‐trinitroresorcinate crystals. Among several crystal growth additives mentioned in the bibliography, we chose carboxymethylcellulose (sodium salt, viscosity 3–4 Pa⋅s), polyvinyl alcohol, as well as two new ones, cationic acrylamide copolymer salt, polyelectrolyte AS‐3605 and acrylic acid–acrylamide copolymer salt, Haicat (PraestrolR 835BS). As a synthesis pattern, we chose an aqueous procedure of synthesis, using solutions of lead(II) or barium salts and magnesium 2,4,6‐trinitroresorcinate. The crystal growth additives were added to one of the solutions, depending on their nature. During the research, most of the attention was focused on crystal size and shape, on safety handling and manipulation, as well as on the yield and process performing facility. The final products were qualified by chemical (Pb and NO2 group contents) and physical (crystal shape and size, bulk density, flowability, and impact and friction sensitivity) analyses.

Effect of selective interactions of ionic acrylamide copolymers on flocculation properties with respect to titanium oxide in aqueous salt solutions

The kinetics of unhindered sedimentation of a titanium dioxide suspension (as model dispersed system) was studied, and the effect of the concentration and mode of addition of various formulations based on anionic and cationic acrylamide copolymers on their flocculation properties in aqueous salt (NaCl) solutions was evaluated.

Successive adsorption of polyacrylamide compounds from electrolyte solutions on the surface of kaolinitic clay particles

Successive adsorption of oppositely charged polyelectrolytes, namely, cationic and anionic acrylamide copolymers, on a solid phase surface from solutions with high ionic strength is investigated. The constants of the Freundlich equation are calculated for the adsorption of different polymers. The interrelation between the adsorption values of polymers and their flocculation activity with respect to clay-salt suspensions is determined. The successive adsorption of oppositely charged polyelectrolytes strongly affects the flocculation due to the formation of polyelectrolyte complexes on the surface of clay particles. The mechanism for complexation is proposed.

Synthesis and Characterization of Hydrophobically Modified Cationic Acrylamide Copolymer

Hydrophobically modified cationic acrylamide copolymers were synthesized by free radical solution copolymerization using potassium persulfate as the initiator. Epichlorohydrin, acrylamide, and tridodecylamine were used to synthesize the hydrophobically modified cationic monomer, i.e., 3-acrylamido-2-hydroxypropyltridodecylammonium chloride (AHPTDAC), which was then copolymerized with acrylamide. The intrinsic viscosity, molecular weight, and charge density of the copolymers depend on the ratio of AHPTDAC and acrylamide used. Fourier transform-infrared (FT-IR) and transmission electron microscopy (TEM) were used to elucidate the structure of the copolymer. The solid copolymer is insoluble in water but only swells in the aqueous medium.

Sedimentation of titanium dioxide suspension in the presence of polyacrylamide flocculants

The kinetics of sedimentation of titanium dioxide suspension in aqueous and water-salt media is studied in the presence of high-molecular-weight flocculants — polyacrylamide and ionic (anionic and cationic) acrylamide copolymers. Data are obtained on the influence of flocculant concentration, the chemical nature of repeating units in polymer chains of acrylamide (co)polymers, and the order of the addition of active components on the sedimentation characteristics of titanium dioxide suspension.

Effect of hydrophobic group on flocculation properties and dewatering efficiency of cationic acrylamide copolymers

Three kinds of hydrophobically modified copolymers of acrylamide with 3-acrylamido-2-hydroxypropyltrialkylammonium chloride were prepared, in which alkyls were ethyl, butyl and octyl, respectively. The conformations of the hydrophobically modified copolymers were studied using TEM micrograph. The flocculation performances and the dewatering efficiencies were investigated. The results showed that the hydrophobic group could enhance the flocculation properties. The longer the hydrophobic alkyl chain was, the better the flocculation result was. Compared with poly-diallyldimethyl ammonium chloride (PDADMAC) and poly-acrylamide (PAM), the hydrophobically modified polymers showed better performances in turbidity removal and were quite more efficient in dewatering examination.

Targeting normal and neoplastic tissues in the rat jejunum and colon with boronated, cationic acrylamide copolymers

A series of boronated cationic copolymers, composed of different ratios of acrylamide, N-acryloyl-3-aminophenylboronic acid and N-acryloyl-diaminoethane (the cationic moiety), were prepared with the intention of localizing boron neutron capture therapy (BNCT) in experimentally induced polyps on the luminal side of the gut of the rat. The goals of this study were to: (a) test the effect of cationization of the boronated copolymers on their uptake by polyps and normal adjacent epithelium; (b) compare the whole rat body distribution of aminophenylboronic acid (APB) and polymeric APB after local application; (c) measure the effect of micro-environmental parameters such as pH, the presence of mucin and cations on the interaction between the APB-copolymers and the epithelium of the rat intestines. Direct analysis of tissue boron levels showed that polymeric APB-uptake was higher in the colonic polyps than in the surrounding normal tissues. Free APB, however, was found in similar quantities in both. When tested in the normal jejunum and colon of the rat, polymeric APB uptake was directly proportional to the molar content of the cationic monomer in the copolymers. The presence of magnesium ions, free boron cationic monomer and mucin interfered with this uptake in a concentration-dependent manner. The uptake was pH-independent at pH 5, 7 and 10. APB accumulation in the colon polyps was inversely proportional to the cationic monomer content in the copolymers, suggesting an increased amount of mucus around the polyps, which probably impeded the electrostatic attachment of the polymer to the malignant tissue. The use polymeric APB for targeting BNCT in perioperative treatment of colorectal carcinoma is suggested, especially in the cases of microscopic residual disease after curative resection.