Antonina Dyuryagina

In this work, the content of recycled polyethylene (rPE) and pigment (Cp), the antioxidant content (CAO) and ratio (RAO), and the peak internal air temperature (PIAT) of the rotational-molding cycle were optimized. Their combined influence on the mechanical, thermal, acoustic, and surface properties of the composites was studied by the probabilistic–deterministic planning method, which reduced the number of experiments from 3125 to 25. Internal stresses were monitored non-destructively through the third-harmonic amplitude (β) of the ultrasonic signal (mirror-shadow method), supported by mechanical testing, thermogravimetric analysis, infrared spectroscopy, and porosity characterization; weather resistance was assessed by accelerated ultraviolet (UV)-B aging for 333 and 666 h, treated as conditional 5- and 10-year service horizons for Northern Kazakhstan rather than as a literal calendar equivalence. The third-harmonic β was shown to be a sensitive correlational marker of internal stresses (R = 0.81 for the mean failure energy (MFE), Fisher-criterion validated), correlating with the elastic modulus, the impact strength, and the environmental stress cracking resistance (ESCR), and tracking the transition between incomplete (ICS), normal (NS), and thermo-oxidative degradation (TDS) sintering; the correlational nature of this evidence is discussed. For products without UV exposure, the optimal formulation (rPE = 25%, PIAT ≈ 200 °C, Cp = 0.1–0.2%, CAO = 0.25–0.5%, RAO = 0.5–1.0) gave a minimum β (0.076–0.09), MFE ≈ 2.6 J/mm, and 2.5–3% porosity; for sun-exposed products, rPE = 25%, Cp = 0.5%, CAO = 0.5–0.75%, and RAO = 1.0 are recommended. An rPE content of up to 50% did not significantly impair thermal stability or surface hydrophobicity, and a nomogram CAO = f(β,rPE) was developed for rapid formulation selection and quality control.

In this work, we optimized three key factors for rotational molding composites: the recycled polyethylene (rPE) content, the pigment (Cp) content, and the process parameter-peak internal air temperature (PIAT). We studied the influence of rPE, Cp, and PIAT on various composite properties. These included mechanical properties (e.g., elastic modulus E), impact strength (MFEsp), surface characteristics (wettability measured by contact angle θ and IR spectroscopy), thermal stability (by DTA–TG analysis), environmental stress cracking resistance (ESCR in hours), and the amplitude of the third harmonic β of the ultrasonic back-wall signal. The IR spectroscopy and contact angle results indicate that adding rPE and pigment slightly increases the composite’s surface hydrophilicity. The results show that PIAT strongly influences all the characteristics of the composites studied. Depending on its percentage, the introduction of rPE can either improve or worsen these composite properties. A correlation was found between β, ESCR, MFEsp, and E, demonstrating that β can serve as a quantitative indicator of internal stress (IS) in rotomolded parts. The recommended optimal composition is rPE 30%, Cp 0.5%, and PIAT 195 °C. Under these conditions, the composite exhibits minimal internal stress and optimal performance, which in turn extends the service life of rotomolded products. Four nomograms were developed: rPE = f(MFEsp, Cp, PIAT) and rPE = f(β, Cp, PIAT), which make it possible to quickly determine MFEsp and β of a product based on the actual PIAT, taking into account rPE and pigment content in the composite (they also allow selecting the rPE and pigment content in the composition depending on the required MFEsp).

Relevance. When processing wood, up to 40% of waste is generated, which includes shavings, sawdust, wood dust, bark parts and substandard wood of various shapes and sizes. Secondary wood waste contains lignin, which is a source for the production of salts of lignosulfonic acids – lignosulfonates. The possibility of using these compounds as pigment dispersants is due to the amphiphilic structure of their molecules. The targeted synthesis of lignosulfonates from secondary wood waste, on the one hand, solves the problems of ensuring waste-free production, and on the other hand, obtaining a marketable product with dispersing properties. Aim. Optimization of the method for obtaining a water-soluble dispersant from wood waste. Methods. Probabilistic deterministic method of experiment planning, spectrophotometry method, computer microscopy method. Results and conclusions. The paper shows the possibility of targeted synthesis of lignosulfonate LSs from birch sawing waste. Optimization of synthesis modes was carried out using probabilistic-deterministic planning methods and a generalized model was obtained that allows estimating the yield of lignosulfonate. The authors studied the effect of three modifiers on the dispersion of titanium dioxide in aqueous acrylic enamel. It is shown that the introduction of LSs, LSt and Dispers 715w at the level of 1.0–0.5 g/dm3 leads to a finer dispersion of the pigment. The best dispersion indicators are observed at a LSs content of 0.5 g/dm3, while the average diameter decreases by 3.1 times (from 8.4 to 2.6 microns). With the content of synthesized LSs at the level of 1.0 g /dm3 in a water-acrylic paint coating, the degree of protection of steel in sulfuric acid solutions was at least 62%.

The aim of the work was to study the effect of additive concentration on changes in the adhesive and cohesive strength of bitumen. To evaluate the effectiveness of modifiers in the composition of binary and triple bitumen systems in relation to mineral fillers of two grades, the method of determination of the adhesive efficiency and thermodynamic calculations of adhesion and cohesion work were used. The following compounds were used as additives: AS-2 synthesized from the oil refining waste and AG-4I (waste sealing liquid). Adhesion–cohesion processes in modified bitumen systems are limited by the wetting effect of crushed stone and the intensity of intermolecular forces in the condensed phase of the binder. In the binary compositions, the addition of modifiers into bitumen significantly improves the cohesive strength and adhesive efficiency in relation to crushed stone. The introduction of AS-2 into bitumen compositions with AG-4I increases adhesion efficiency and thermodynamic work of adhesion in relation to the filler surface. The adhesion efficiency and thermodynamic work of adhesion in the “bitumen-AG-4I-AS-2” system reach their maximum at C_AG-4I = 3.0 g/dm³ and C_AS-2 = 1.5 g/dm³. In these concentration modes, the composition ensures maximum increase in adhesion efficiency (A_KS = 65.18%; A_KA = 48.11%) and the greatest increase in thermodynamic work of adhesion (W_A(KS) = 15.79 mN/m; W_A(KA) = 14.13 mN/m).

The purpose of these studies was to establish the influence of the microstructural and rheological characteristics of modified bitumen compositions on the strength indicators of asphalt concrete. The effect of additives concentration on the rheological characteristics and microstructure of binary “bitumen–surfactant”, “bitumen-AG-4I”, and ternary “bitumen-AG-4I-AG-4I” systems has been studied. To assess the effect of bitumen dispersion on the physical and mechanical characteristics of modified asphalt concrete samples, the compressive strength value was determined. The following chemicals have been used as additives: the original product AS-1, industrial additive AMDOR-10, and used sealant AG-4I, a product based on polyisobutylene and petroleum oils. At an increased content of AG-4I (C ≥ 1.0 g/dm³) in ternary systems, the contribution of the emerging intermolecular polyisobutylene network to the development of structuring processes increases while the viscous effect of the surfactant AS-1 decreases. It has been established that the minimum size of bee-like bitumen structures (1.66 µm) is recorded with the joint presence of additives in the bitumen, AS-1 at a level of 1.0 g/dm³ and AG-4I at a level of 1.0 g/dm³. Under the same concentration regimes of the ternary bitumen composition, the maximum increase in compressive strength R_D was achieved with the smallest size of bee-like structures of modified bitumen.

The purpose of this study was to optimize the processes of wetting fillers by varying the content of such additives as a surfactant and polymer in bitumen–mineral compositions in order to achieve optimal performance. The cosine of the contact angle was used as a criterion for assessing the adhesion of the bitumen binder to the surface of crushed stone. The effect of the additives’ concentration on surface tension and adhesive efficiency in binary and ternary bitumen compositions was studied. The following chemicals were used as additives: the original product AS-1, industrial additive AMDOR-10, and used sealant AG-4I, a product based on polyisobutylene and petroleum oils. AS-1 was obtained from the oil refining waste in the laboratory of M. Kozybayev North Kazakhstan University. The ternary “bitumen–AG-4I–AS-1” composition provided a maximum decrease in the contact angle by 15.96° (gray crushed stone) and by 14.06° (red crushed stone) relative to original bitumen, providing better wettability of the mineral filler particles with the bitumen, and as a result, maximum adhesion between the bitumen and crushed stone. The optimal performance of the bitumen–mineral composition was recorded with the joint presence of additives in the bitumen: AS-1 at a level of 1.0 g/dm3 and AG-4I at a level of 1.0 g/dm3.

Improving the durability of asphalt concrete road surfaces by increasing their moisture resistance is an urgent task. Modified bituminous binders should be compacted into coatings with the lowest possible water saturation. The purpose of this study was to establish the effect of modifiers on the hydrophobicity of bituminous films in order to achieve minimum water saturation and to build a mathematical model of the wetting process with water. As modifiers, we used a product of amination of distillation residues of petrochemistry, waste sealing liquid (a solution of high molecular weight polyisobutylene in mineral oil), and a condensation product of polyamines and higher fatty acids. The water-repellent effect of modifiers was studied by measuring the contact angle of bituminous film with a water drop. The water saturation of asphalt concrete samples was determined by the amount of water absorbed by asphalt concrete at 20 °C. A close correlation was revealed between the hydrophobicity of modified bitumen and the water saturation of asphalt concrete. Generalized equations and a graphical representation of a function of several variables allowed for optimizing compositions by the content of modifiers to achieve the required performance properties of asphalt concrete coatings.

Tanks made of three different brands of rotational polyethylene (DOW, ELTEX, and M350) with three degrees of sintering (normal sintering (NS), incomplete sintering (ICS), and thermally degraded sintering (TDS)) and three thicknesses (7.5 mm, 8.5 mm, and 9.5 mm) were explored. It was found that the thickness of the walls of the tanks did not have a statistically significant effect on the parameters of the ultrasonic signal (USS). An increase in temperature caused a decrease in the USS parameters. According to the temperature coefficient of stability, the ELTEX brand of plastic can be distinguished (from DOW and M350). The ICS degree of the sintering of the tanks was revealed from a significantly lower amplitude of the bottom signal, compared with NS and TDS degree samples. By analyzing the amplitude of the third harmonic of the ultrasonic signal (β), three degrees of the sintering of containers NS, ICS, and TDS were revealed (with an accuracy of about 95%). Equations β = f(T, PIAT) were derived for each brand of rotational polyethylene (PE), and two-factor nomograms were constructed. Based on the results of this research, a method for the ultrasonic quality control of polyethylene tanks manufactured using rotational molding was developed.

The aim of this study was to optimize the composition of enamel consisting of aluminum pigment and polyphenylsiloxane polymer, in order to achieve the maximum aggregative stability of suspensions. Sedimentation rate (SR) was used as a criterion for assessing the aggregative stability of the suspensions. An original product, AS-1, and industrial additives PEPA and Telaz, were tested as surfactants. AS-1 was obtained from oil refining waste at M. Kozybayev North Kazakhstan University. All the studied surfactants improved the stability of the suspensions. The AS-1 additive significantly improved the stability of the suspensions, but exhibited a lower stabilizing ability by 10–20% than PEPA. The maximum overall stability of the suspensions was recorded at a PEPA level of 0.25–0.375 g/dm³ in the enamel. The Taguchi method was used to optimize the composition of the enamel, using AS-1 as the surfactant. It is recommended to use AS-1 in silicone enamels. Optimum compositions can reduce the petrol absorption of coatings by 1.5 times, their roughness by 2.5 times and increase their gloss.

This article presents the results of studying the disaggregation of titanium dioxide in water-dispersion compositions based on an acrylic film-forming agent under the action of a surfactant. The possibility of using polyether siloxane copolymer (PC) and sodium polyacrylate (NaPA) in paint and varnish compositions as modifying additives of the dispersing effect is proved. The correlation between the dispersing effect of surfactants and the amount of their adsorption on the pigment is proved. NaPA, which provides a greater reduction in adsorption strength, demonstrates a greater dispersing effect than PC. It was found that the larger the size of the aggregates of pigment particles, the greater the disjoining pressure created by the surfactant. An equation is derived that generalizes the cumulative contribution of surfactant concentration and the content of the film-forming agent in suspensions to the average particle diameter of pigment. The introduction of NaPA in the amount of 0.25 g/dm³ into the paint allows the rate of acid corrosion to be reduced by 2 times, the number of pores in the coating to be decreased, and the adhesion of the coating to be significantly increased (by 2 points according to ISO 11845: 2020).