Nanotechnologies in Construction: A Scientific Internet-Journal

176-189

Authors: Korolev E.V., Grishina A.N., Inozemtcev A.S., Ayzenshtadt A.M.

Introduction. The study of the kinetics structure formation is rarely the subject of a careful study. Although it is important for materials used to create elements of building structures, energy elements, thermoelements and materials for other purposes. The article proposes refinements of the methodology for determining the parameters of the kinetics structure formation of cement composites, including modified compositions. Methods and materials. The structure formation of cement systems with plasticizers, microsized mineral additives (hydrosilicates of barium, copper and zinc) and nanosized particles of zinc hydrosilicates has been studied. Results and discussion. It is proposed to single out two stages of initial structure formation: the stage of setting the cement paste and the stage of hardening. The selection of the setting stage is connected with the natural laws of the development of natural systems, namely, the initial formation of a structural grid obeys an exponential law. Moment of time when a deviation from this law is observed is the time of occurrence of spatial and/or prescription difficulties that hinder the exponential development of the system. Conclusions. A strong negative relationship between the parameters φ and β of the equation H(t) = a exp(φt β) has been established. These parameters characterize the rate of structure formation at the setting stage (parameter φ) and the density of the structure (parameter β or the internal dimension Di, 0 associated with it). The presence of such a negative relationship indicates the inadvisability of accelerating the processes of structure formation at the stage of setting. This is supported by a strong positive relationship between the period of initial structure formation t0, s1 and the strength of the material R28.

198-204

Authors: Qinglin Liu, Huanyu Ye, Zhihong Zhang, Rongming Wang

Metal nanocrystals exhibit unique properties due to their high surface-to-volume ratio and have great potential for applications in the fields of electronics, magnetics, optics and catalysis. However, their high specific surface area leads to easy coarsening in operation, which may greatly degrade their performances, especially when they are exposed to various chemical environments or at high temperatures. Therefore, the direct visualization of nanocrystals' structural evolution when they are coarsening is crucial to gain insight into the mechanism and develop more effective means to improve the size stability of nanocrystals. In this work, we investigated the structural evolution of Pt nanocrystals with sizes of ~ 4 nm on SiNx film in both oxidizing and reducing atmospheres at a moderate temperature (300о С) in the aberration-corrected environmental transmission electron microscopy (ETEM). The sizes of nanocrystals remain almost unchanged when annealed in the oxygen atmosphere with volatile PtOx formation on the surface, hindering nanocrystals sintering and leading to Pt loss. On the other hand, obvious coarsening of nanocrystals resulting from Ostwald-ripening and nanocrystal migration and coalescence was observed in the reducing atmosphere. Our findings reveal the dynamic structural evolution of nanocrystals in different atmospheres and provide possible ways to improve the size stability of nanocrystals

217-226

Authors: Belozerov V.V., Belozerov Vl. V.

Introduction. Recently, much attention in the publications of scientists has been paid to “nature-like technologies” in the use of RES – renewable energy sources (sun, wind, heat). At the same time, foreign business, despite the fact that these sources are low concentrated and seasonal, is actively investing in their development. In Russia, these processes have been developing slowly, and therefore, on the basis of a system analysis, it seems relevant to justify the correct vector of application of RES. The article provides evidence of the insolvency of opinions about the insufficiency of the assimilation potential of the biosphere to compensate for the economic activity of mankind. In this connection, the scientific, technical and socio-economic tasks arise for the “reengineering of the technosphere” in the structure of the life support systems of society, including educational facilities. Methods and models. To solve these scientific, technical and socio-economic issues, by analogy with individual residential buildings, it is proposed to use “nature-like nanotechnologies” in the engineering systems of schools, and for evaluation - the method of retro-forecasting the results of introduction of domestic innovations, which has proved its adequacy when solving the problems of fire and environmental safety of the technosphere in the regions of the South of Russia. Results and discussion. The results of the synthesis and “virtual implementation” of autonomous engineering systems for school buildings are presented, which allow for the decentralization of electricity, water and heat supply by generating resources (water, heat and electricity) using the “Shukhov wind-electric installations” combined with a vortex system extraction of moisture of air, with their duplication by hydro panels and solar batteries. The calculations have demonstrated that the putting into production of such domestic innovations and the «reengineering» with their help of the engineering systems of 40 thousand Russian schools will allow autonomization and proper electricity, water and heat supply, which will ensure their safe functioning in compliance with GOST 12.1.004. Moreover, after the introduction of an autonomous engineering system in the school, due to the annual savings in budget subsidies for “pedagogical services”, it becomes possible to increase the monthly salary of each school teacher by 30–40 thousand rubles. Conclusion. The conducted studies confirm the results obtained in the synthesis of autonomous engineering systems for individual residential buildings, unequivocally determining the place of RES in the structure of resource supply systems for cities and rural settlements.

241-249

Authors: Maskova A.R., Yarmukhametova G.U., Rakhmatullina R.G., Sabitov I.N., Aminova G.K.

Introduction. Polyvinyl chloride (PVC) is the world's leading synthetic polymer in industrial use. Products based on PVC have firmly taken on the world market, and currently there is no highly developed country that is able to avoid its production and consumption. The high demand for thermoplastics is primarily due to its unique properties such as durability, resistance to climatic conditions, low flammability, good barrier properties, economy, environmental friendliness and versatility. The complex of technological and service properties of soft PVC, in addition to other additives, is mainly provided by plasticizers, the content of which can reach 50% or more. It is the efficiency of the plasticizing that has a decisive impact on the characteristics in the resulting materials and products. One of the most widely used classes of compounds in the plasticization of PVC are phthalic acid esters, in particular, dibutyl phthalate (DBP), di-(2-ethylhexyl)-phthalate (dioctyl phthalate, DOP), diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP). Phthalates have found the greatest use as plasticizers due to their properties: good compatibility with PVC, low migration from plastic compound, minimal interaction with the polymer at room temperature, good frost resistance, high electrical insulating properties, availability, manufacturability and low cost. Methods and materials. The paper presents methods for the obtaining of novel symmetrical and asymmetric phthalate plasticizers: dibenzoxyethyl phthalates, benzylbenzoxyethyl phthalates, phenoxyethylbenzoxyethyl phthalates, ethoxyoctylbenzoxyethyl phthalates – by catalytic esterification of phthalic anhydride with oxyethylated phenylcarbinols, phenols and 2-ethylhexanols. The conditions for the synthesis of target products with the maximum yield were selected. The physicochemical properties of the obtained compounds were studied. The obtained experimental data were used to identify promising novel plasticizers of the phthalate type by cluster analysis. Cluster analysis for decision making is the most effective, as it is designed to combine some samples into classes (clusters) in such a way that the most similar in properties get into one cluster, but at the same time, samples of different clusters differ from each other as much as possible. Clustering carried out in the program Statistica 10. Results and discussion. According to the data obtained, it is found that benzylbenzoxyethyl phthalates and ethoxyoctylbenzoxyethyl phthalates have the best characteristics in terms of plasticizing ability. We study the influence of the selected plasticizers on the physical and mechanical characteristics of PVC compositions The effectiveness of compounds in the PVC composition is evaluated in terms of “elongation stress” and “breaking stress”. The test results of the samples are compared with the indicators of PVC compounds containing DBP. Conclusion. The use of the developed additives contributes to the production of PVC compounds with improved physical and mechanical characteristics