E. V. Vorob’eva

Effect of polyacrylic acid and polyethylene glycol on the crystallization of calcium carbonates in the presence of magnesium ions

The effect of polyacrylic acid and polyethylene glycol on the crystallization of calcium carbonates in the presence of magnesium ions was studied. It was found that the presence of magnesium ions in solution and the treatment temperature (80°C) influence the formation of the final products of calcium carbonate crystallization. In binary mixtures, low-molecular-weight polyacrylic acid and polyethylene glycol affect synergistically, and such mixtures can be used for selectively influencing the formation of calcium carbonate polymorphs.

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.

Performance of a phenolic antioxidant introduced by different procedures into polyethylene containing dispersed fillers

The performance of Irganox 1010 phenolic antioxidant was studied in relation to the procedure of its introduction into a stock of the polymer and dispersed filler powders. Three procedures were used for introducing the antioxidant: the antioxidant was deposited onto the surface of filler (procedure I) or polymer powder (procedure II) particles prior to mixing the components, or it was deposited after mixing the polymer and filler powders (procedure III). We studied mixtures with an inert filler (aluminum oxide) and with fillers active in polymer oxidation and regeneration of the phenolic antioxidant (dispersed zinc, zinc oxide). The film samples for the studies were prepared from powder stocks by hot pressing. The antioxidant performance was evaluated by the induction period of oxidation, which was determined from the time dependences of accumulation of carbonyl groups in the polymer structure.

Effect of binder reagents of varied nature on the strength of potassium chloride grains

Specific features of structure formation in dispersed salt systems based on potassium chloride were studied from the standpoint of a relationship between the physicochemical properties of binder reagents, granulation conditions, and grain strength.

Peculiarities of the formation of polyacrylamide compound-based polyelectrolyte complexes in the course of the flocculation of clay-salt dispersions

Peculiarities of the formation of polyelectrolyte complexes based on cationic and anionic copolymers of acrylamide having different macromolecule charge densities on the surfaces of kaolin particles in highly concentrated salt solution are investigated. The interactions of the copolymers with the clay particle surface and with each other are studied by electrokinetic and IR spectroscopy methods. The rheological properties of kaolin suspensions are investigated in a salt solution in the presence of the polyelectrolytes. The flocculation ability of the polyelectrolytes and their binary mixtures with respect to clay-salt dispersion is estimated. The mechanism for the formation of polyelectrolyte complexes on the surface of clay particles is discussed. It is shown that the complexation of oppositely charged polyelectrolytes on the surfaces of clay particles intensifies the flocculation of clay-salt dispersions.

Decrease in the performance of a phenolic antioxidant in preparation of inhibited polyethylene films by hot pressing

The effect exerted on the efficiency of the polymer inhibition by the conditions (pressure, treatment time, antioxidant concentration) of preparing films of polyethylene with Irganox 1010 phenolic antioxidant by hot pressing was studied. Blends of the antioxidant with the polymer were prepared by treatment of the binder particles with a solution of Irganox 1010 in acetone. After drying to remove the solvent, films were prepared from the dry blends by hot pressing. The films were subjected to oxidation in the molten state in air. Evolution of the characteristic IR absorption bands of the antioxidant and polymer was monitored. The inhibition efficiency was evaluated by the induction period of the film oxidation. Two interrelated processes occur concurrently in the course of hot pressing: sorption uptake of the antioxidant, resulting in its more uniform distribution in the bulk of the sample, and a decrease in the relative content of hydroxy groups, i.e., partial degradation of the inhibitor. The latter process can decrease the efficiency of the polymer inhibition. Therefore, in development of polymer compounds with enhanced oxidation resistance, it is necessary to optimize the process conditions, namely, the composition of the ingredients, the procedure for introducing the antioxidant, and the temperature and time of sample preparation.

Phase separation of salt dispersions of clay with polyacrylamide flocculants

Effect of polyacrylamide (co)polymers on the properties and structure of floccules formed in the course of phase separation of a salt dispersion of clay was studied. It was shown that, with a binary system of unlike-charged copolymers, a sediment with high density and water-yielding capacity is formed, which is necessary for the effective phase separation. The subsequent squeezing of the flocculated sediment to remove water leads to a local increase in the concentration of polymers in the solid phase, which raises the plastic strength of the sediment and improves the granulation conditions.

Quantitative estimate of contents of organic additives in potash fertilizers by the IR spectroscopy method

Qualitative and quantitative examination of organic additives applied for hydrophobization of potash fertilizers was fulfilled using the IR Fourier spectroscopy of diffusion reflection. The results obtained have formed a basis for the development of the technique of measuring weight fractions of organic components added to potash fertilizers of “Belarus’kalii” Joint Stock Company and for the calculation of the metrological characteristics.

Contact oxidation of inhibited polyethylene on copper at nonuniform antioxidant distribution

The oxidation resistance of polyethylene films in which the antioxidant is concentrated exclusively in the surface layer of the polymer or in the layer contacting with the support was studied. Specific features of oxidation of polyethylene films with heterogeneous distribution of an amine (Neozon D) or phenolic (Irganoks 1010) antioxidant on a catalytically active copper support were examined in relation to the kind of the antioxidant.

Polyacrylic acid and formulations based on it as inhibitors of deposit formation in water-recycling systems

The performance of polyacrylic acid of various molecular weights and of its formulations with sodium tripolyphosphate and Na2EDTA as inhibitors of deposit formation and as dispersants was examined.