Evaluation of Corrosion Resistance in 3.5% NaCl Solution of Hybrid Coatings Obtained from Plastics Materials

In this work, the corrosion resistance of hybrid coatings obtained from plastic materials was evaluated and compared with the corrosion resistance of Zn coatings. Zinc and hybrid coatings were obtained by electrodeposition from zinc sulphate electrolyte. For obtained hybrid coatings it was used as disperse phase two type of plastic materials: phenol-formaldehyde resin and epoxy resin. Polarization was used to measure the corrosion rate and behaviour of zinc and hybrid coatings in 3.5% NaCl solution. Tafel curves show that the including particles of plastic materials in zinc matrix disturbs the cathodic reactions and reduces anodic reaction leading to decrease of corrosion current and increase the corrosion resistance of hybrid coatings obtained at the same electrodeposition parameters as zinc coatings. Smallest values of corrosion rate were evaluated for hybrid coatings obtained with phenol-formaldehyde resin as disperse phase that indicates a good corrosion resistance in 3.5% NaCl solution.

Concentrations and regularities of disperse-phase distribution of organochlorine pesticides, polychlorinated biphenyls and polycyclic aromatic hydrocarbons in natural water

<div><p>This article presents the monitoring results of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) in surface water of the Dnieper River for the period 2011–2019. Total levels of OCPs, PCBs and PAHs consist of 1,4–17,1; 2,8–57,2; and 7,5–378,6 ng/L, respectively. A significant increase in pollution levels was not identified. Research results of the disperse-phase distribution of these substances in water were also provided. Less than half of the total contents of pollutants were in the water phase. Average water-soluble parts of OCPs, PCBs, and PAHs accounted for 32, 42, and 44 %, respectively. It was shown that water-soluble parts of individual pollutants decrease with the increase in <span style="text-decoration: line-through;">the</span> coefficients of hydrophobicity of compounds. The clearest reliable, relevant correlation between water-soluble parts of individual congeners and coefficients of hydrophobicity was obtained for PCBs.</p></div><p align="center"><strong><br /></strong></p>

To the Question of Analytical Estimate of Evaporation Time of the Drop, Crossing Through the Heat Media

Due to the kinetic approach the modelling description of the drop evaporation is offer. The main equation of the theory received due to the conservation law of dissipative functions of the vapor – liquid system. The diapason of drop size it’s finding when its stability. It’s comparison of the results with the famous classical is given. The numerical estimate of the linear size of small disperse phase when take place usually evaporation (i.e. the Knudsen’s number is a small Kn = l R ≪ 1, where l is a free length path of the molecule and R is an drop radius) are given

The Role of Surface Phenomena in Modified Cement Dispersions at Studying Poly-Functional Modifiers' Mechanism of Action

The research findings of colloid and chemical properties of poly-functional modifiers (PFM) with various chemical compositions and qualitative and quantitative proportions of polar organic substances with various molecular weights have been presented. The possibility of regulating the properties of PFM and concrete mixes, modified by them by means of not only changing the chemical composition of modifiers, but combining the types and quantity of active admixtures of polar organic substances with various molecular weights has been shown. It has been demonstrated that the modifiers under study possess the surface activity at solid-solution phase boundary, reducing the surface tension σsolid-liquid (σs-l) At the same time the surface tension at the solution-air phase boundary can remain the same or reduce to a certain extent depending on the modifier’s chemical composition. PFM and superplasticizer (SP) SB-3, which have, unlike SP S-3, the certain surface activity at solid-solution boundary, increase the air entrainment into concrete mix by 0.5÷1.5%, additionally increasing the freeze-thaw resistance of concretes of both fluid and equal-workable compositions without affecting their strength. The adsorption of modifiers on the disperse phase of suspension is conditioned by dispersion forces and, independently of its kind, is of monomolecular nature. For the localization of PFM molecules on the surface of a particle, its molecule should have a system of bonded aromatic rings or conjugated double bonds. The adsorbed modifier’s molecules should make the disperse phase surface hydrophilic and for this purpose they should contain hydrophilic groups along the full length. All this predetermines the role of adsorption-solvation factor in modifiers’ mechanism of action.