Статьи журнала - Nanotechnologies in Construction: A Scientific Internet-Journal
Все статьи: 452
Achievements of nanoindustry: projects, applications, economic effect and social significance
Статья научная
In the paper the review of achievements of nanoindustry is carried out: the use of nanosilica as an additive that improves the fire and thermal resistance of cementitious composites; a welding filler reinforced with nanoparticles for aerospace structures; smart, mobile and autonomous station for collecting and accumulating solar and electric energy; materials authentication with the use of nuclear quadrupole resonance spectroscopy, etc. Areas of application, economic effect and social significance of projects developed in different countries are given. For example, researchers and developers at Ben-Gurion University in the Negev, Israel and Ulyanovsk state technical University, Russia have jointly created a device in the field of alternative energy that allows you to collect and store solar and electric energy for later use. The device has a unique smart system of protection against voltage interruptions and overheating due to the controller devices and software. Also, the device has a number of innovative engineering solutions to reduce the temperature of the heated elements of the device, increase protection from dust and moisture. All this together is a unique solution different from the existing solutions capable of generating and storing solar energy for a long time (up to 10 years).
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Acoustooptic shutter for glass units
Статья научная
Introduction. The use of liquid crystals is attractive for solving technical problems when creating a new generation of monitors, pressure sensors, seismic activity, determining the level of dry or liquid media, indicators of the concentration of harmful substances due to the small size of devices, low power consumption, simple design, low cost, and easy controllability of liquid crystals by various external fields. Under the action of mechanical shear, the liquid crystal layer is deformed, as a result of which surface polarization occurs. The purpose of the research is to conduct an experimental study of the effect of an electric field on flexopolarization occurring in a thin layer of a liquid crystal to create an acousto-optic shutter. Materials and methods. Nematic liquid crystals 10 – 100 μm thick with homeotropic orientation of molecules were used as materials: n – methoxybenzylidene n – butylaniline; 4 – octyl – 4 – cyanobiphenyl; nitrophenyloctyloxybenzoate; cyanophenyl ester of heptylbenzoic acid. Methods. The experimental setup consisted of a charge-sensitive amplifier with a high input resistance of 10 GΩ and a selective amplifier (2 MΩ). The design of the amplifier made it possible to apply a constant voltage of up to 100 V to its input, as well as linear and synchronous signal detections, which were then fed to the ADC that recorded them. Results and discussion. The behavior of charges induced on the surface of a liquid crystal due to internal mechanisms of molecular-orientation polarization was considered as a function of the magnitude and direction of the external electric field. For this, a liquid-crystal layer (MBBA) was placed in an electric field. The dependences of the first U1ω and second U2ω harmonics, when a positive potential is applied to a deformable plate, reach lower values than with a negative one. The electric field at a positive potential stabilizes the molecules of the polarized layer, and at a negative potential it makes it less stable, which leads in one case to a decrease in the slope angle on the surface, and in the other to an increase, which leads to an increase in the second harmonic. Under weak boundary conditions, a polar deformation occurs in the bulk of the NLC. When the field is applied to the homeotropic layer of NLC (CPEHBA), the value of the second harmonic U2ω increases linearly from the voltage Uc up to the achievement of “saturation”, which is due to an increase in the stabilizing dielectric moment over the viscoelastic one. At low fields (Е ≤ 104 V/cm), the value of U2ω first increases and then decreases due to an increase in the tilt angle of the director relative to the normal to the surface. At low polarizing voltages Uc ≤ 15 V (CPEHBA) dependence U1ω is approximated by a power function of the Uc 3 type, at Uc >> 15 V the second harmonic U2ω depends as Uc –1. At low bias voltages, the position of the minima of the values of the first U1ω and second U2ω harmonics (for MBBA and CPEHBA) does not coincide with the zero point along the abscissa at Uc = 0. The harmonics U1ω and U2ω have a maximum when a positive potential is applied to the moving electrode. In the region of positive displacement voltages, the molecules stabilize, while at negative voltages, the molecules are less resistant to orientational perturbations. The value of the second harmonic U2ω sharply decreases with the perturbation frequency. Conclusion. The obtained research results can be used in the development of pressure sensors, seismic sensors for buildings and structures, light modulators, as well as an acoustooptic switch for glass units.
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Additives to reduce the flammability of polymers
Статья научная
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.
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Adsorption treatment of sewage sludge from heavy metals
Статья научная
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.
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Статья научная
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.
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Anti-icing coating based on silicone resin SILRES® MSE100
Статья научная
Introduction. The study is aimed at obtaining an anti-icing coating for building structures by creating a hydrophobic surface layer, which is regulated by surface energy and surface topography. Materials and methods. Acrylic resins A-01 and DEGALAN®, high-chlorinated polyethylene resin HCPE and silicone resin SILRES® MSE 100 were used in the research. Aerosil R 972 nanoparticles were used as a filler. The anti-icing properties of the coating were evaluated by the contact angle of the water drop with the coating, the static and dynamic contact angle, the wetting hysteresis, and the adhesion of ice to the superhydrophobic surface. Results and discussions. We have found that coatings based on acrylic resins A-01, DEGALAN®, high chlorinated polyethylene resin HCPE and silicone resin SILRES® MSE100 20% concentration do not provide superhydrophobic properties. The superhydrophobic effect is retained by coatings based on SILRES® MSE100 silicone resin 5% and 10% concentration. The force of detachment of a drop from a coating based on SILRES® MSE100 silicone resin at a 10% concentration is 3 times less, which ensures an easier rolling of a water drop from the surface and its anti-icing properties. The amount of ice on an untreated surface is 0.59 kg/m2, and on a surface treated with a composition based on SILRES® MSE100 silicone resin, it is 0.15 kg/m2. Conclusions. An anti-icing coating composition based on SILRES® MSE100 silicone resin has been developed. The proposed composition forms a coating characterized by anti-icing properties that remain in operation.
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Статья научная
Introduction. In connection with the growing demand for living and working conditions in civil and industrial construction, there is an increasing need for high-quality building materials with the required set of performance properties. Polymer reinforced composite materials are promising materials in the construction industry due to their high strength, durability, reliability and economy. Polymers such as polyvinyl chloride, polyurethanes, polyacrylates, epoxy resins, polypropylene are used in construction for the manufacture of decorative elements, self-leveling floors, coatings for appliances and equipment. However, the use of polymeric materials creates risks of electric shock due to the generation of static charge. The use of electrically conductive nanomaterials as fillers makes it possible to reduce the resistivity of polymeric materials and slow down the flow of electric charges. Main part. This review article presents the benefits and drawbacks of antistatic additives for polymer materials used in industry and in the construction industry. Conclusion. An analysis of the literature has shown that over the past seven years, the largest number of relevant papers has been devoted to carbon materials as antistatic additives (8 articles), metal and metal oxide nanoparticles (7 articles), ionic liquids (7 articles), and polyaniline (7 articles). The most studied characteristics of antistatic polymer materials are the specific surface RS and volume RV resistances. According to the reviewed articles, metal and metal oxide nanoparticles are the most suitable antistatic additives to polymeric materials, since they are well dispersed in the polymer matrix. However, further research is needed to eliminate the negative effect of nanoparticles on the mechanical properties of polymeric materials.
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Статья научная
Introduction. The application of nanocomposites in various industries has increased in recent years due to their unique properties and performance characteristics. Enhancing the quality performance of nanocomposites presents a formidable challenge, primarily attributable to the intricate interactions among their constituent elements. This paper presents an overview of the methods used to analyze and calculate the quality performance of nanocomposites using PVC as the base material. Methods and materials. To calculate technological parameters that are not directly measurable, we conducted a thorough analysis of literature sources related to the specific process under consideration. Through this analysis, we established appropriate relationships between empirical data in accordance with the fundamental principles of thermodynamics and mass transfer processes. In the course of the research, the method of neural networks was applied in order to describe the process of vinyl chloride polymerization carried out by suspension method. To solve this problem, a cascade network with forward propagation of the signal and backward propagation of the error was applied. Network composition: in the hidden layer – ten sigmoid neurons, in the output layer – two linear neurons. Results and Discussion. Throughout this research, it was observed that the heat flux during polymerization exhibits temporal variation, contingent upon the concentration level of the initiator. Further the dependencies obtained can be used in controlling the flow rate of refrigerant into the reactor cooling jacket, to ensure that the entire process is isothermal. It was found that by varying the stirrer speed, it is possible to change the particle size and hence the molecular weight distribution of polyvinyl chloride. The developed neural network was tested. The obtained results have minimal error and are close to the real values, from which we can conclude that the network is trained correctly and the dependence between the data is found. Conclusion. Dependencies linking physicochemical parameters of the technological process with the design features of the apparatus have been established. To maintain the quality of PVC, in particular the appropriate molecular weight distribution, a neural network (a cascade network with direct signal propagation and reverse error propagation, consisting of ten sigmoidal neurons in the hidden layer and two linear neurons in the output layer) was developed in MATLAB environment. The network was trained on a sample and tested on test values, which showed that the network predicts the outcome of the process with minimal tolerable error, with other parameters unchanged.
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Application of statistical methods for solving problems of construction materials science
Статья научная
In the areas of construction materials science, the most promising solution is a set of issues related to the study of the influence of conditions for the formation of the material structure, including the possibilities of its self-organization, on its properties. The chemical and physical aspects of this influence are studied at the micro level, using the entire complex of “subtle” studies. At the same time, there are methods that allow us to assess the possibility of nanoeffects in experiments carried out at the macro level: in production or in the laboratory. One of these methods is the method described in the article. The main provisions of the methodology have been formed on the basis of statistical methods for conducting experiments and studying technological processes. This technique can significantly reduce the number of experiments performed while maintaining the adequacy of the results obtained and makes it possible to perform further analytical optimization of the results and their engineering interpretation. In particular, application of this technique allows evaluating joint influence of various factors on the result, that makes it possible to identify synergistic and antagonistic effects and then test them at the micro level by studying the nanostructure of materials. The article, as an example, considers the technology of concrete, focused on the utilization of concrete scrap as a filler or filler in building materials for various purposes. The results of research on the development of composite binder compositions based on fine-ground concrete scrap waste, mineral binder, synthetic fibers and polymers cured as a result of chemical interaction with the components of the concrete mixture are presented. This binder can be used for making various wall elements of buildings.
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Arrangement of chemical elements in the three-dimensional matrix
Статья научная
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.
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Статья научная
Introduction. When using water suspensions of finely dispersed mineral systems of natural and anthropogenic origins as active agents in the production of concrete composites, an important factor in their effective use is to ensure the aggregative and sedimentation stability of solid phase particles before adding the solid phase into the reaction mixture. Methods and materials. The paper provides an algorithm for quantifying stability criteria according to the DLVO theory provisions as exemplified by a suspension of fine polymineral sand powder from the Kholmogorskoye deposit in the Arkhangelsk region (average particle size is 195 nm). In order to successfully assess the aggregative stability of this colloidal system, it is necessary to conduct experiments for determining the analogue value of the Hamaker constant, which was 0.5 •10–20 J for the mineral sand studied, in addition to experiments for determining the zeta potential of particles. This paper presents the results of the analysis according to the criteria of the value of the interaction energy (Uint) and the sedimentation rate (Vsed) of a polymineral sand dispersed system (water suspension) calculated taking into account the analogue value of the Hamaker constant, zeta potential and dimensional characteristics of its solid phase particles, physicochemical properties of the dispersion medium. Results and discussion. It is shown that the determining factor of the aggregative stability of the suspension is the electrostatic barrier for particle interaction. Theoretical calculation showed that the aggregative stability of the system may be affected by its particles reaching their zeta potential of approximately 10–4 mV (a nearly isoelectric state). It is proposed to use the kinetic parameter of sedimentation – its velocity – to assess the kinetic (sedimentation) stability of this suspension – resistance to gravity, i.e. the ability to resist the dispersed system stratification due to the difference in particle densities between the dispersed phase and dispersion medium. Conclusion. The sedimentation rate is Vsed ≈ 4 nm/sec for the object under study in water dispersion medium with the averaged dimensional characteristics of 195 nm. At such a rate of solid phase particle precipitation, a dispersed system based on finely crushed polymineral sand from the Kholmogorskoye deposit can be considered sedimentatively stable.
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Статья научная
Introduction. Activated sludge is one of thepulp-and-paper industry waste types. Within the framework of the rational natural resources’ utilizationand the waste recycling, due to its composition, activated sludge could be subjected to certain technological solutions for the production of nanofertilizers, since it has been previously the basis for making of various soils and biological products. However,occasionally the composition of activated sludge may contain different toxic compounds, heavy metals, and their impact on soil fertility and plants vital state is profound. Thus, the purpose of our research is to study the effect of the activated sludge introductionas a basis for nanofertilizers on the heavy metals contentin podzolic soils of various granulometric composition in agricultural exploitation. Methods and materials. Research was conducted under the conditions of dummy experimentin vegetation vessels. We have used podzolic soils of various granulometric composition (clayey, loamy, sandy) and pulp-and-paper industry waste – activated sludge in concentrations of 1; 2.5; 5 and 10% of the dried soil weight. Determination of the heavy metals gross content has been carried out by the atomic absorption method with measurement on the AA-7000 spectrophotometer (Shimadzu, Japan); mobile fraction of heavy metalsdetermination (подвижныеформы) – utilizing acetate-ammonium buffer solution by inductively coupled plasma mass spectrometry methodology. Results and discussion. The paper presents the results of the research on mobileand gross forms of heavy metals in podzolic soil of various granulometric composition when applying activated sludge as the basis of organic nanofertilizer under the dummyexperiment. Conclusion. It was shown that the content of mobile and gross forms of the studied metals (Fe, Mn, Cu, Zn, Ti, Al, Ni, Co, Cr, Cd and Mo) were within the health-based exposure limits, with the exception of Cd gross form, where the maximum excess was 2.5 MAC (maximum allowable concentration).
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Статья научная
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.
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