The results of the specialists’ and scientists’ researches. Рубрика в журнале - Nanotechnologies in Construction: A Scientific Internet-Journal
Additives to reduce the flammability of polymers
Scientific article
Introduction. This review article provides data on additives used to reduce the flammability of polymer compositions. It is shown that not individual substances are used for this purpose, but their mixtures, including flame retardants, synergists, and stabilizers. The principle of operation of flame retardants is that when the appropriate degree of concentration of flame retardants in the material is reached, they do not allow it to burn without the presence of an ignition source. Under the influence of fire on the processed material, various chemical and physical processes occur in it, preventing the flame from flaring up. Main part. The advantages and disadvantages of the main flame retardants currently used, which include antimony compounds, halogen-containing compounds, phosphorus-containing substances, as well as aluminum and magnesium hydroxides, are analyzed. Various mechanisms for slowing down combustion processes when flame retardants are used are considered. It has been shown that bromine-containing flame retardants are much more effective than chlorine-containing ones. They decompose in a narrow temperature range. In addition, plastics containing bromine compounds as flame retardants are easily recycled due to the high thermal stability of such flame retardants. Phosphorus-containing compounds have a plasticizing ability and increase the fire resistance of plastic compounds. The action in the condensed phase is that during the decomposition of the flame retardant, phosphoric acid residues are formed, which act as dehydrating agents, contributing to the formation of carbonized structures. In this case, an aerosol can also be formed, which contributes to the deactivation of radicals due to the wall effect. Of particular interest are compounds containing halogen and phosphorus. The advantages of these compounds are as follows: by splitting off halogen radicals during decomposition, they deactivate active radicals; contribute to the formation of carbonized structures. Metal hydroxides decompose under the influence of high temperatures with the release of water. The decomposition reaction is endothermic, resulting in cooling of the substrate to temperatures below the flash point. The formation of water contributes to the dilution of combustible gases released during decomposition, weakens the effect of oxygen and reduces the rate of combustion. The effectiveness of hydroxides is directly proportional to their content in the polymer. The greatest efficiency is observed when aluminum hydroxide is introduced into oxygencontaining polymers (polyethylene terephthalate, polybutylene terephthalate, polyamide). Magnesium hydroxide is more expensive than aluminum hydroxide, but has a higher heat resistance (up to 300оC). Conclusion. Thus, among the listed flame retardants, aluminum and magnesium hydroxides occupy the first place in terms of the volume of use (more than 40% of the total volume of flame retardants). This is due to their low cost, manufacturability of their application and environmental safety. A well-chosen metal hydroxide system produces a low-cost non-combustible material with little fumes from decomposition. Therefore, the use of metal hydroxides as flame retardants is constantly increasing.
Free
Adsorption treatment of sewage sludge from heavy metals
Scientific article
Introduction. Because of urban development the volume of municipal and industrial wastewater are growing. Along with them the amount of sewage sludge (SS) also increases. Millions of tons of SS are currently accumulated on the territory of the Russian Federation and contain various pollutants, including heavy metals (HM). In this regard, the search for effective methods of SS treatment from HM is an urgent problem. The main methods of SS treatment are drying, dehydration, thermal methods, UV and microwave wave treatment. These kinds of disinfection eliminates many pathogenic microorganisms, but they are quite expensive and not effective against HM. Reagent methods include SS disinfection with quicklime (CaO). However, decontamination requires large doses (up to 30%) and it is also ineffective against HM. Humic-mineral reagent are more effective, they are based on crushed caustobiolites, their cleaning capacity from HM is 19–87%. Methods and materials. The authors have previously shown the effectiveness of wastewater treatment from HM using sorbents based on dolomite, quartzite, and waste from mining and processing plants. Therefore, a method for SS treatment from HM using sorbents based on dolomite, humates, and CS containing CaCO3 and humic compounds was proposed. In this regard, a method was proposed for SS treatment from HM using three types of sorbents based on: 1) waste of thermal power plants (TPP) – conditioned sludge (CS) containing CaCO3 up to 68% and humic compounds up to 12% – sorbent 1 (S1); 2) dolomite – Mg and Ca carbonate in a composition with sodium humate (25%)– sorbent 2 (S2); 3) modified dolomite with sodium humate (1%) – sorbent 3 (S3). Results and discussion. In laboratory experiments, the cleaning capacity of SS was studied using a dolomite-based sorbent modified with humate (1%). In field tests, a decrease in the concentration of HM in SS was studied with the use of sorbents based on CS and the complex sorbent dolomite-humate (75:25). The cleaning capacity of SS from HM increases in the series: sorbents based on waste from TPP – CS containing CaCO3 and humates (cleaning capacity E = 4.8–48.6% for dried SS and 29.3–53.3% for dehydrated SS) < sorbent based on a composition of dolomite with humate (E = 65.1–92.1% for dried and 56.6–89.4% for dehydrated SS) < a dolomite-based sorbent modified with humate (E = 90.8–99.9%). Conclusions. The maximum cleaning capacity is shown by a dolomite-based sorbent coated with a nano- and micro- sized layer of sodium humate.
Free
Advancing Decision-Making: The Role of Management Analytics in Modern Business Practices
Scientific article
Introduction. Management analytics is an evolving field that has gained substantial traction in both academia and industry due to its profound impact on decision-making processes. The inte-gration into decision making of advanced information technologies and AI drive innovative solutions within management analytics. Evolution of Management Analytics. The discipline integrates statistical analysis, predictive modeling, and data visualization to optimize business strategies, operational efficiency, and financial performance. As management practices advance, they contribute new dimensions to data collection and analysis, presenting unique opportunities to boost nanotechnologies. Methodological Advances in Management Analytics. This study explores the transformative effects of management analytics across diverse sectors by illustrating its evolution and interpreting its methodologies with special focus on nanotechnologies. Applications in Different Sectors. Management analytics significantly enhances decision-making through sophisticated data analysis, offering strategic insights that propel efficiency and competitiveness. The use of management analytics in nanotechnologies raises questions regarding ethical implications and regulatory considerations. Challenges and Future Directions. However, integration complexities, data security, and the need for skilled personnel pose ongoing challenges. Conclusion. This review provides insights into the potentials of the development of management analytics and its importance in contemporary management.
Free
Scientific article
Introduction. Traditional Portland cement-based concretes are characterized by low flexural tensile strength and a tendency to crack formation. One of the promising ways to solve this problem is the use of carbon nanotubes, which act as crystallization centers and provide discrete reinforcement of the material at the nanoscale. The aim of the work is to experimentally confirm the effectiveness of using a nanomodifier based on CNT “Taunit-m” in the composition of fine-grained concrete. Materials and methods. M500D0 Portland cement was used as a binder, sand from the Pescovatsky quarry was used as a fine filler, and crushed stone of 5–20 mm fraction was used as a coarse filler. The complex additive included the superplasticizer “SP-3” and CNT “Taunit-M.” Nanotubes were introduced into a dry cement-sand mixture using a linear induction rotator liv-100, which provides homogenization and mechanochemical activation. The phase composition was studied using a Bruker d8 Advance diffractometer. Results and discussion. It was found that the maximum increase in strength was achieved with a CNT content of 0.005% of the cement weight: compressive strength increased by 29%, bending strength increased by 23% compared with the control composition. X-ray phase analysis data showed a 25% increase in the degree of hydration of the lithic phase, as well as accelerated formation of portlandite and ettringite. Non-destructive testing confirmed that by the 7th day of hardening, the increase in compressive strength was 25%, which indicates an intensification of structure formation. The effect is explained by the uniform distribution of CNTs and the mechanochemical activation of the surface of cement grains in LIV-100. Conclusion. The introduction of carbon nanotubes “Taunit-m” in combination with superplasticizer “sp-3” and the use of linear induction rotator liv-100 can significantly improve the strength characteristics of fine-grained concrete. The increase in strength correlates with an acceleration of hydration and a change in the phase composition of the cement stone. The optimal concentration of CNT is 0.005% by weight of cement.
Free
Scientific article
Introduction. Unauthorized dumps are territories that are not permitted and not equipped in accordance with the current legislation of the territory, where waste products are disposed of. Most of the unauthorized dumps, both industrial and municipal solid waste (MSW), are objects of accumulated harm. In connection with the increase in the use of nanoparticles of various genesis in engineering materials, there is a need to assess their impact on environmental components and human health. One of the main marker substances that determine the ecotoxicological effect of dumps are heavy metals, including those entering the environment in the form of metal-containing nanoparticles. Their identification, determination of the processes of horizontal and vertical migration of pollutants (P), identification of the intensity of negative processes are necessary information for making decisions on the choice of methods and technologies for recultivation of disturbed areas. Currently, there are no legislative acts (LA) that take into account the specifics of such objects in the study of territories within the framework of environmental surveys (ES), which necessarily precede the implementation of project documentation for recultivation. A vital task is to develop a methodological approach to diagnosing the state of territories disturbed as a result of waste disposal, and to reliably determine the boundaries of soil pollution, taking into account modern trends in the development of nanotechnology. Methods and materials. The analytical study was based on the results of environmental surveys at four unauthorized dumps of the Republic of Bashkortostan (three dumps for municipal solid waste (MSW) and one dump for industrial waste), carried out in 2019–2020. Results and discussion. A study of the reliability and completeness of determining the level of soil pollution in the territory of the dumps was made. Deviations from the requirements of СS 11-102-97, GOST 17.4.3.01-83 in terms of the number of sampling points and their spatial location were revealed. It was found that the requirements of Article 1 and Article 80.1 of the Federal Law of 10.01.2001 No.7-FL “On Protection of Environment” on identifying negative environmental changes and establishing the ability of pollutants to migrate to other components of the environment were not taken into account. Conclusions. The existing methodological approaches to establishing the boundaries of soil pollution in the areas where unauthorized dumps are located require revision and specification.
Free
Scientific article
Introduction. Nanotechnology has received a lot of attention in the oil and gas industry as an effective means of improving properties and increasing production rates, especially in harsh environments such as ultra-deep and shallow gas fields, deviated and horizontal wells, geothermal zones, and high pressure/high temperature (HPHT) areas. These environments present numerous economic, technical, operational, and HSE challenges that need to be addressed.Cementing operations play a critical role in these environments, as the cement sheath serves as a barrier to meet the different well conditions, including pressure, temperature, and the flow of liquids or gases. The use of nanomaterials as additives to cement has been credited with improving its properties and performance under these complicated conditions. Methods and materials. The study presents an analysis of the effect of pressure and temperature on the behavior and complexity of cementing operations in high-pressure wells. Analytical performance of the main characteristics of nanoclay (structural and mechanical) and evaluation of its effect on the durability and strength of cement slurry during well construction are presented. Results and Discussion. The results of the study allow us to conclude that nanoclay can be widely used as an additive to improve the durability and properties of cement-based materials under difficult conditions. Conclusions. The results of this study provide valuable information to researchers, engineers and practitioners in the field of cementing oil and gas wells, especially in solving problems related to providing the most favorable conditions for well operation with the long-term use of more durable cement slurry.
Free
Arrangement of chemical elements in the three-dimensional matrix
Scientific article
It is emphasized in the article that thanks to the discovery of D.I. Mendeleev and the Periodic Table of chemical elements existing for more than 150 years, as well as the international table IUPAC, chemistry has been actively developing and keeps developing. A new model for arranging chemical elements in the form of a three-dimensional matrix has been proposed. This makes it possible to predict new elements with the designation of nuclear masses and the electronic structure of shells. There have been developed new patterns according to the cyclicity (block structure) of horizontal rows and the structure of vertical groups and their physical conception have been specified.
Free
Scientific article
The wettability of a surface of channels filtering liquids and gases under natural conditions of oil and gas reservoirs is one of the parameters that largely determines the filtration. A nature of the filtration channel surface wettability determines a phase permeability, capillary forces and intensity of adsorption at the interface. An ability of the filtration channel surface to be wet by the polar or nonpolar phases of formation fluid and process liquids affects the filtration-capacitive parameters of oil and gas saturated rocks. In this regard, in the development of oil and gas fields, much attention is paid to the study of physicochemical phenomena and processes occurring at the interfaces. An article presents the results of a set of laboratory experiments to study the surface activity of the colloidal system in the form of an emulsion with supercharged nanoparticles. A set of filtration experiments was carried out using the United States Bureau of Mines (USBM) method in order to assess an effect of the emulsion system with nanoparticles on wettability of the surface of oil and gas reservoir rock filtration channels. The research was conducted on rock cores of two oil and gas fields in the Ural-Volga region of the Russian Federation. According to the applied experimental procedure, rock cores were preliminarily maintained under reservoir conditions to give a surface of pore channels the properties close to the natural conditions. After that, the wettability of rocks was assessed by measuring the USBM wettability index before and after filtering the emulsion system with nanoparticles. Analysis of the research results showed that filtration of the emulsion system with high surface activity led to a change in the wettability of rocks from completely hydrophilic (USBM index – 0.60) to completely hydrophobic (USBM index – minus 0.32). The research results allowed to conclude that there is a high potential for application of emulsion systems with supercharged nanoparticles to control the filtration of formation fluids and process liquids in natural oil and gas reservoirs.
Free
Scientific article
Introduction. Tubular electric heaters are widely used in industrial and domestic heating applications. Structurally, tubular electric heaters consist of a metal shell housing a heating element, with the space between them filled with a high-temperature, heat-conducting dielectric material. A tubular electric heater is divided into several zones: the active (heating) zone, the cold zone (contact terminal zone), and the transition zone. The “cold” sections of the tubular electric heater, where the contact rods connected to the terminal wires are located, are the most critical in terms of electrical safety and durability. This zone requires reliable electrical insulation, sealing from the external environment (moisture, corrosive environments, dust, aggressive vapors), and mechanical fixation of the current-carrying elements. The aim of this study was to develop and optimize the composition of a sealing material for the cold section of a tubular electric heater. Materials and Methods. To achieve this goal, a series of pilot samples of sealing materials for protective insulating coatings were manufactured by modifying their compositional components: the polymer base, plasticizer, and filler. Samples of sealing materials for the cold section of tubular electric heaters were subjected to a comprehensive evaluation of their adhesive strength, oil-and-petrol resistance, dielectric and mechanical properties, and chemical resistance. Results. The paper presents an analysis of the feasibility of using an insulating nanomaterial for the cold section of a tubular electric heater. The results of a study of materials with various compositions, including Ammerheim Phenol Epoxy phenol-epoxy coating, T-111 epoxy resin, F-4D fluoroplastic suspension with nanoscale particles, one-component silicone sealant, ethyl cellulose, VIKSINT PK-68 organosilicon rubber, and SEDM-6 epoxy resin, showed that the most promising material for sealing the "cold" section of a tubular electric heater is F-4D fluoroplastic, which exhibits unique chemical resistance to gasoline, oils, and aggressive environments, a wide operating temperature range (from –190 to 250 °C), and excellent dielectric properties. Conclusion. Based on the results of the tests, fluoroplastic F-4D was selected as the sealing dielectric material for the “cold” section of the cartridge electric heater. This material possesses the necessary properties for operation: heat resistance, oil-and- petrol resistance, dielectric strength, high ductility, and chemical resistance. However, the fluoroplastic F-4D-based composition requires additional modification to improve adhesion to the metal surface of the tubular electric heater.
Free
Changes in permeability and microstructure of sand during reinforcement with polyurethane resin
Scientific article
Introduction. In complex geotechnical conditions during construction and operation of engineering structures, polyurethane compositions are used to strengthen loose soils. Analysis of current research has shown that the effect of polymers on sandy soil filtration properties is poorly studied. The purpose of this study is to determine the dependence of permeability and microstructure of chemically strengthened sand on the treatment method, polyurethane resin consumption and external compressive loads. Methods and Materials. Experiments are carried out with fine and medium-grained sands. Two-component highly elastic and one-component polyurethane resins are used for strengthening. Their main purposes are soil stabilization, waterproofing, and formation of cutoff curtains. The effect of the resins on rock permeability and microstructure is assessed based on the experimental results. The experiments include formation of the polymer-sand mixtures using one-solution and two-solution resin treatments with resin/rock volume ratios of 0.05–0.25, microstructure study and filtration tests under various sample loading conditions. Results and discussion. The dependence of the sand permeability on the method of strengthening with polyurethanes has been determined. In the case of one-solution treatment with highly elastic resin with composition/rock volume ratio of 0.2, the permeability of the samples is 7–13 ·10–3 μm2. A two-fold decrease of the resin content causes an increase in permeability by 1–2 orders of magnitude. Such behavior is explained by the structure in which open intergranular pores predominate and form connected pore channels. The addition of a small volume of a one-component rigid polyurethane composition reduces sand permeability by 1.5–3.2 times and improves the stability of samples under compressive loads. Conclusion. The practical significance of the results consists in the increasing efficiency of sand filtration properties reduction with polyurethane resins strengthening. The proper choice of a chemical treatment method with consider of the geotechnical problem provides both effective rock permeability reduction and decrease in the consumption of expensive polymer compositions for the construction of cutoff curtains and screens in the rock mass.
Free
Comparative efficiency analysis of biocides and conserving agents for cement-based systems
Scientific article
Introduction. The use of biocides in primary and secondary protection ensures prolonged biological resistance of building materials. However, assessing their potential in cement systems requires a comprehensive analysis, taking into account the alkalinity of the environment, chemical compatibility with binder components, and the selection of an effective concentration. This article presents a comparative analysis of the resistance of biocides, conserving agents, and auxiliary components to Aspergillus niger micromycete to justify their applicability for protecting cement composites from biocorrosion. Materials and methods of research. The efficiency of biocides (alaminol, polyhexamethylene guanidine hydrochloride (PHMG), food conserving agents (sodium propionate, nisin), and additional components (butylene glycol, hydroxypropyl methylcellulose (HPMC)) against the micromycete Aspergillus niger, which is highly resistant to adverse conditions, was analyzed. A series of aqueous solutions of the additives studied were used at the dosages recommended by the manufacturers. Fungicidal and fungistatic activity were assessed based on the mycelial growth inhibition zone and fungal growth rate. Results and discussion. PHMG demonstrated the highest biocidal effictiveness against Aspergillus niger, providing complete suppression of test culture growth across the entire concentration range. The growth of the inhibition zone from 4 to 7 mm correlated with an increase in the biocide dosage from 1% to 5%. Modification of the samples with alaminol at concentrations of 5% and 8% resulted in the formation of an inhibition zone of 3–4 mm and the absence of visible mycelial growth. The remaining additives studied (sodium propionate, nisin, HPMC, and butylene glycol) did not exhibit any independent fungicidal activity under these conditions. Conclusion. The study conducted gives grounds for the perspective of using polyhexamethylene guanidine hydrochloride as an effective bioprotective agent for cement composites.
Free
Scientific article
Introduction. Reducing the density, increasing the strength and other physical-technical characteristics of lightweight concretes are urgent tasks of modern building materials science. To solve them, it is necessary to consider new approaches to the development of compositions of cement systems using effective porous aggregates, binders, chemical and mineral additives, including different nanomodifiers (carbon nanotubes, fullerenes, nanoparticles of SiO2, Al2O3, Fe2O3, etc.). The complexity of designing modified cement concretes is largely due to their multicomponent nature and a large number of parameters affecting the key characteristics of material. The qualitative solution of such multicriteria problems is possible with the complex implementation of rational physical and computational experiments using mathematical modeling and computer technology. New opportunities for modeling of structure formation processes and predicting properties of multicomponent building materials are emerging with the development of machine learning methods. The purpose of this study is to develop machine learning algorithms that can efficiently establish quantitative dependences for the compressive strength of modified lightweight concretes on their composition, as well as to identify the optimal variation ranges of prescription parameters based on the obtained multifactor models to achieve the required level of controlled mechanical characteristic. Methods and materials. The processing and analysis of experimental research results were carried out using modern methods of machine learning with a teacher used in the problems of regression recovery, knowledge extraction and forecasting. To implement the developed machine learning algorithms, libraries in the Python programming language, in particular NumPy, Pandas, Scikit-learn, Matplotlib, Seaborn, were used. Results and discussion. It is established that the gradient boosting model is the most accurate type among the obtained machine learning models. It is characterized by the following quality metrics: R2 = 0.9557; MAE = 2.4847; MSE = 12.7704; RMSE=3.5736; MAPE = 11.1813%. According to the analysis of this multifactor model, the optimal dosages of pozzolanic and expanding modifiers amounted to 4.5–6.0% and 6.0–7.5% of the binder weight (Portland cement + modifier), respectively, which ensured achievement of the required level of compressive strength (40–70 MPa) of lightweight concretes at the age of 28 days at material density reduced by 3–10% (the range under consideration is 1200–1900 kg/m3). Conclusions. Thus, the study results show the prospects of using machine learning methods for design compositions and predicting properties of multicomponent cement systems.
Free
Scientific article
Introduction. Currently, fluorine polymers have become quite widespread in various industries. One of the fields of application of fluoroplastic coatings in the oil industry is their use as protective coatings to prevent the deposition of paraffin plugs on the walls of tubing and field pipelines. Fluoroplastic parts find promising application in machines and units of oil refining and petrochemical industries, where high corrosion resistance, sufficient strength and high tribotechnical properties are required. The complexity of the ubiquity of fluoroplastic coatings is its low adhesion to the metal surface. In this regard, fluoroplastic coatings are typically complex systems comprising directly fluoroplastic polymer, binders and functional fillers. Materials and methods. The study used metal plates made of titanium alloy VT6 and carbon steel St3 coated with an aqueous fluoroplastic suspension. Fluoroplastic polymer coatings have poor adhesive strength to the metal surface on which they are applied. Therefore, in order to ensure a high level of adhesion of the coating to the metal substrate, it is necessary to use complex methods of preliminary surface preparation. The coating was applied to the pre-prepared surface of the metal plates by air spraying using a spray gun and compressed air. The key parameters for the formation of the fluoroplastic film were drying and sintering modes. Adhesion was evaluated by the methods of “X-shaped” notch (State Standard 32702.2-2014) and tearing in a tensile machine on cylinders (State Standard 32299-2025). Results. Proposed method comprises application of intermediate primer layer from suspension containing chromium (III) oxide, phosphoric acid, water and fluoroplastic. The intermediate adhesive primer layer was applied by air spraying under the same conditions as the base fluoroplastic coating. This ensured that the proposed drying and sintering conditions met the base layer. The use of a primer made it possible to realize a gradient transition from the metal substrate to the fluoroplastic layer and significantly increase the adhesion properties. Conclusion. The results show a significant improvement in adhesion compared to the control samples without primer: the tensile strength value by the tear method is 2.56 N/mm2, and by the X-notch method - from 5 points to 1 point (traces of peeling or removal of the coating along the incisions). The method is easy to implement and promising for use in protective coatings.
Free
Creation of polymer composites with mineral fillers
Scientific article
Introduction. Currently, the development of science and technology requires the creation of new polymer composites with high technical characteristics for various industries. One of the primary methods to improve the physical and technical characteristics of polymer composites based on thermoplastic elastomers is by incorporation of natural fillers. In the Kyrgyz Republic, there is particular interest in using fine mineral fillers extracted from local natural resources. The minerals and rocks found in the region are characterized by high availability, extensive reserves, and a variety of properties. The accumulated experience in research and practical application opens up prospects for using these materials to create polymer composites with unique characteristics. This opens up new possibilities for using the cavitation process in various industrial applications, including the grinding of materials. Methods and materials. An experimental hydrocavitation mill has been developed to produce fine powders from minerals and rocks intended for use as fillers in polymer composites. The physicochemical properties of polymer composites and their raw materials were studied using modern instruments and equipment. The fractional composition and physical and technical characteristics of some minerals and rocks used to obtain active fillers for polymer composites are given. Results and Discussion. The fractional composition of crushed fillers with a particle size of less than 0.31 mm is distributed as follows: finely ground basalt – 7.3%, wollastonite – 44.6%, marble dust – 50.26%, brown coal powder – 47.56%. The analysis shows that among the studied fillers, finely ground basalt contains the smallest amount of fine fractions, which is due to its high hardness compared to other minerals such as wollastonite, marble, and coal. Physical and mechanical studies of the resulting polymer composites showed that when finely ground basalt is added, an uneven distribution of basalt powder in the polymer matrix is observed, which leads to a decrease in the strength characteristics of the composite. Therefore, to obtain a more durable material, it is necessary to grind minerals and rocks to the level of microparticles using the cavitation effect. For this purpose, a laboratory mill was created that operates based on the cavitation effect. Fillers at the level of micro- and nanoparticles were obtained using the developed hydro cavitation mill. The physical and technical characteristics of polymer composites with additives of the resulting nanofillers have been determined. The compressive strength of composites with mineral fillers (fraction less than 0.31 mm, content of wollastonite filler in the composite – 25.2%) was 5.47 MPa, with basalt filler – 5.2 MPa, and with leather powder (dust) – 4.25 MPa. Fillers at the level of micro- and nanoparticles were obtained using the developed hydro cavitation mill. The physical and technical characteristics of polymer composites with additives of the resulting nanofillers have been determined. The compressive strength of composites with mineral fillers (fraction less than 0.31 mm, content of wollastonite filler in the composite – 25.2%) was 5.47 MPa, with basalt filler – 5.2 MPa, and with leather powder (dust) – 4.25 MPa. The compressive strength of the composite with the addition of carbon filler (13.2%) was 4.2 MPa. The introduction of up to 14.2% of mineral fillers into the composition of the composite increases its heat resistance: when adding basalt filler – up to 106 °C, and wollastonite – up to 114 °C. Conclusion. The fractional composition of mineral fillers based on inorganic raw materials studied for their use in creating polymer composites. A hydro cavitation mill was made and a method for processing fillers from minerals and rocks was developed. New polymer composites were obtained with the addition of basalt, wollastonite, marble, and leather industry waste. Studies have been carried out on the physical and technical characteristics of these polymer composites depending on the content of fillers, such as basalt, wollastonite, marble and leather industry waste.
Free
Development of new methods for energy technology processing of Kyrgyzstan coals
Scientific article
Introduction. This study explores methods for determining the yield of volatile matter from Kyrgyz coal and obtaining ultra-pure carbon for potential applications in modern carbon nanotechnologies used in the construction industry. Both organic and inorganic components of various coal types were analyzed, along with the composition of the released volatile substances. Methods and materials. We used in the research empirical methods (observation, experimentation, measurement, and comparison), alongside chemical methods involving acid treatment (for the removal of metallic impurities) and a transport reaction method (for the removal of silicon oxide impurities). The study focused on obtaining ultra-pure carbon from bituminous coal deposits in Kyrgyzstan. The tested raw materials included grey and brown coals from deposits in the southern region of Kyrgyzstan. Pre-weighed samples were placed in a stainless-steel reactor and subjected to slow pyrolysis under sealed conditions across specific temperature ranges. For brown coal, pyrolysis was conducted between 100 °C and 550 °C, while for bituminous coal the range was 100 °C to 1100 °C. The process continued until all liquid and gaseous pyrolysis products ceased to be released. Results. Pyrolysis was used to remove volatile liquid and gaseous impurities from the coal samples. The qualitative and quantitative composition of the volatile gases was determined. During pyrolysis in the 100 °C to 850 °C range, pyrogenetic water was formed, and gaseous products such as NO, CO₂, CO, H₂S, CH₄, and others were released. For brown coal, the yield of volatile substances at 150–170 °C was 61.9%. For bituminous coal, at 380–400 °C, the yield was 15.5%. Post-pyrolysis, the remaining coal contained only solid impurities – primarily metallic elements and silicon dioxide (SiO₂). These were removed using a chemical method involving a mixture of concentrated sulfuric and nitric acids in a 1:3 ratio. Silicon dioxide impurities were removed via a transport reaction facilitated by gas convection. As a result of this two-stage purification, ultra-pure carbon consisting solely of carbon atoms (C–C–C–) was obtained. Conclusion. The proposed experimental setup and technological scheme for impurity removal and carbon purification – including the use of transport reactions – enable industrial-scale production of ultra-pure carbon from coal. This purified carbon can be used as a component in advanced construction nanomaterials. The use of such materials significantly enhances the performance characteristics of construction structures and coatings, while also reducing the environmental impact of combustion by-products, ultimately lowering costs associated with environmental protection.
Free
Development of the actual state principle for a physical system
Scientific article
Introduction. The article briefly discusses the state of scientific research in the field of mathematical modeling of physical systems with distributed parameters. Mathematical modeling in elasticity theory. The initial boundary value problem of linear elasticity theory is formulated. It is shown that using measured and unmeasured variables, it is possible to construct a positive definite energy relationship, which allows not only to use the variational technique to find an approximate solution, but also to design objective estimates of its quality. Two-dimensional problem of elasticity theory (static case). Using the example of solving a two-dimensional static problem of linear elasticity, the advantages of the proposed approach are discussed in detail. Mathematical modeling in fluid theory. The variational principle in fluid theory is formulated. Optimal pressure control. Using the example of solving the problem of the motion control for ideal and viscous fluids in pipeline systems, the issues of finding an approximate solution and estimating its accuracy are discussed. Energy principle in the heat transfer problem. The variational principle in the linear heat transfer problem is formulated. Two-dimensional heat transfer problem. The features of constructing a solution to a control problem in a two-dimensional heat transfer theory are discussed in detail. Generalizing principle. A generalizing principle of the actual state of a physical system is formulated, which can be effectively applied for a detailed description and analysis of physical processes.
Free
Scientific article
Introduction. The effect of adhesion additive and nature of filler on fatigue life and interfacial interaction in mastic is analyzed in this paper. Materials and methods of research. Frequency sweep from 0.1 to 100 rad/s at strain 0.05% at temperatures from 30 to –10°С with a step 10°С and cyclic tests (LAS test) at temperatures from 16 to 1°С with a step 3°С for bitumen grade BND 100/130 and mastics based on it, containing fillers of different nature, were performed on the dynamic shear rheometer. Mastics were prepared by mixing bitumen (3 min; 160°С and 600 rpm) and filler (filler volume fraction – 0.275). Adhesion additive in an amount of 0.7%, was introduced into bitumen before the filler to investigate the effect of AD on the properties of bitumen and AB. The damage characteristic curve under cyclic loads was calculated using two models of VECD theory (Viscoelastic Continuum Damage Modeling System): dissipated strain energy and pseudo-strain energy. Results and Discussion. The influence of nature and properties of filler, adhesive additive, temperature and frequency of tests on the parameter of interfacial interaction K-B-G* and thickness of adsorbed layer has been investigated. The intensity of damage in the specimen under cyclic loads and the behavior of fatigue parameters as a function of test temperature at two variants of determining the parameter α have been analyzed. Conclusion. It is shown that an increase in the interfacial layer thickness in asphalt mastic leads to an increase in their resistance to damage accumulation (Damage Intensity) during fatigue testing (LAS), and lowers the rate of pseudo-deformation energy growth.
Free
Scientific article
Introduction. The article addresses the problem of improving the lubricating capacity of drilling fluids to reduce the coefficient of friction in a ”metal-to-metal“ pair, which is crucial for preventing stuck pipe incidents and reducing equipment wear during directional and horizontal drilling. Methods and materials. An analysis of modern approaches to the use of lubricating additives in drilling fluids is presented. The effect of various types of additives – paraffins, ”EZО“ nano-additive, fatty acids, waste oil, as well as compositions with surfactants – on the coefficient of friction and friction reduction efficiency in a polymer-clay fluid was experimentally studied. Tests were conducted on an OFITE E.P. lubricity tester at additive concentrations ranging from 0.2–2.0% by volume. It was shown that the greatest effect is achieved with the combined use of surfactants and nano-hydrocarbon components, providing a reduction in the coefficient of friction of up to 71% at an oil content of 2%. Results and discussion. Optimal component concentrations were established and synergy effects were identified upon the combined introduction of additives. The obtained results allow recommending the developed nano-compositions for use under high-load conditions in a ”metal–metal“ friction pair during high-angle drilling. Conclusion. Based on the conducted research, it was established that the highest efficiency (reduction of the friction coefficient up to 71%) is achieved with the combined use of surfactants and waste oil at a concentration of 2%. A synergistic effect was revealed upon the combined introduction of additives, and it was also established that exceeding the oil concentration above 0.5% reduces the efficiency of most additives, with the exception of compositions with surfactants. The developed formulations are recommended for use as a cost-effective and efficient alternative for lubricating ”metal-to-metal“ sliding contact during horizontal drilling.
Free
Scientific article
Introduction. In the article the use of powder elastomeric modifier capable of rapid breakdown into micro- and nanofragments upon contact with hot bitumen to improve the low-temperature properties of bitumen is presented. The indicators of resistance to cracking are determined by various methods and their dependence on the thermal history of the samples. Methods and Materials. At temperatures up to –36оC the oscillatory rheological tests (4-mm DSR test) of RTFO-aged samples of bitumen BND 60/90 and modified binder (MB) which contain the active powder of discretely devulcanized rubber (APDDR) produced by high-temperature shear-induced grinding from the crumb rubber of worn tires have been conducted. MB was prepared by mixing bitumen (3 min; 160оC and 600 rpm) with 12.5 wt.% APDDR. Results and Discussion. The effect of the test parameters on the rheological parameters has been studied. Structural transitions in bitumen and MB by methods of differential scanning calorimetry (DSC) and the cracking temperature of the same samples in static conditions in the ABCD test were detected. It is revealed: a decrease in the temperature of actual cracking of the MB sample compared to bitumen. Conclusion. It is shown that APDDR as a modifier affects the structure of bitumen and reduces the temperature sensitivity of bitumen to external influences.
Free
Energy efficiency for pitched roof insulation system
Scientific article
Introduction. Energy efficiency is a comprehensive criterion that accounts for both manufacturing and installation costs of products, as well as resource savings during structure operation. Optimizing energy costs in product manufacturing and material selection becomes essential, considering the specific operational characteristics of individual construction systems. Methods and Materials. Soft stone wool slabs, glass mesh, and modified epoxy resin-based adhesive served as starting materials. The structure was examined using a FEI Quanta 200 scanning electron microscope. Product properties were determined following standard methods. Operational durability assessment employed an accelerated hydrothermal treatment method applied to mineral wool cylinder fragments using a setup developed by Moscow State University of Civil Engineering (MGSU)–GASIS(HSE)–MAXMIR, evaluating changes in product compressibility. Results. Thermo-humid exposure had minimal impact on changes in average product density, with variations within experimental error. The binder type showed no significant influence on product characteristics across all stages of temperature-humidity exposure. However, sample mass loss due to thermo-humid exposure and airflow was substantial, necessitating slab reinforcement on surfaces contacting the ventilated space of pitched roofs to resist airflow. Discussion. Properties of mineral wool products with reinforced outer layers fully satisfy the operating conditions of thermal insulation materials in pitched roof systems, which experience temperature and humidity fluctuations, as well as dynamic loads from airflow in ventilated spaces. Conclusion. The research resulted in the development and testing of a novel product: soft and semi-rigid mineral wool slabs reinforced with glass mesh. These slabs maintain equivalent thermal characteristics and manufacturing costs to conventional analogs while exhibiting significantly enhanced operational stability, thereby ensuring greater overall system durability. Product energy efficiency was comprehensively evaluated.
Free
