The article presents research of the influence of the electromagnetic vortex layer on the structure formation of cement stone during the activation of portland cement, both without additives and with carbon nanotubes modification. It has been shown that the storage of portland cement powders in open air for 60 days after activation in the electromagnetic mill leads to partial carbonization, wherein the role in absorption reducing of the super plasticizer additive is increased since there is more uniformly localization of the additive on the surface of the portland cement particles. The processing of portland cement in the electromagnetic mill leads to the physical activation of portland cement, which is accompanied by an increase in the amount of heat generated by the hydration of portland cement and the rate of hydration. Thus, the rate of hydration of compositions activated in the electromagnetic mill isincreased 1.615 times at the temperature of the thermostat 22 °C; 1.85 times at 40 °C; 2.71 times at 60 °C; 2.3 times at 80 °C. The modification of cement stonewith carbon nanotubes, which was obtained from portland cement activated in an electromagnetic mill, leads to a higher quantity of silicate phase of portland cement (by 12–39%), as confirmed by a decrease in the number of portlandite in these compositions by 8% in comparison with control composition.

The IR spectra of calix[6]arenes with adamantylacetic acid (1) and adamantyl (2) substituents along the upper rim of the molecule were studied. It was shown that the formation of an intramolecular H-bond between carboxyl groups on the upper rim of the calix[6]arene molecules with adamantylacetic acid fragments does not weaken the cyclic cooperative H-bond at the lower rim of the macrocycle, which is confirmed by DFT calculations. The calculation has shown that molecules 1 and 2 take on the conformation of a compressed cone. The reactivity of adamantylcalix[6]arenes changes due to the association of carboxyl groups. The formation of dimeric complexes due to H-bonds of carboxyl groups along the upper rim of molecule 1 does not lead to a noticeable redistribution of the charges of hydroxyl groups on the lower rim. Heating a sample of 1 to a temperature of 180 degrees C destroys a small part of the H-bonds between neighboring carboxyl groups, as evidenced by the appearance of a weak band at 3535 cm(-1). However, after cooling to room temperature, the H-bonds between the carboxyl groups are restored. Heating up to 355 degrees C-leads to irreversible changes in the H-bonding system, but even at this temperature, structure destruction has not been observed. (C) 2021 Elsevier B.V. All rights reserved.

The IR spectra of p-(3-carboxy-1-adamantyl)thiacalix[4]arene (1) were studied. IR spectra of compound 1 do not contain bands of free hydroxyl groups. The νOH value at 3377 cm-1 signifies the formation of an intramolecular H-bond along the lower edge of compound 1. It was found that all the studied calixarene derivatives containing adamantylcarboxylic acid fragments on the upper edge form H-bonds between adjacent carboxyl groups. At the top edge of thiacalixarene, carboxyl groups form dimers or cyclic tetramers through intramolecular H-bonds. The conformation of the cone is preserved, but there is a mutual influence of Hbonds along the lower and upper edges of the thiacalixarene molecules. A structure with dimeric H-bonds between carboxyl groups is 1.5 kJ/mol less preferable than the conformation with tetrameric cyclic H-bonds of compound 1. Comparison of the νOH absorption frequency of alcohol hydroxyl groups in IR spectra of thiacalixarenes shows that the presence of the second H-bond system weakens the H-bonds of alcohol hydroxyl groups slightly.

The IR spectra of p-(3-carboxy-1-adamantyl)thiacalix[4]arene (1-AdCOOHTC4A) have been studied. IR spectra of crystalline 1-AdCOOHTC4A obtained at room temperature or upon heating to 250 °C or its dilute solutions lack bands of free hydroxyl groups. The frequency of hydroxyl groups at 3377 cm−1 indicates the formation of an intramolecular H-bond along the lower rim of the 1-AdCOOHTC4A molecule. On the top edge of thiacalixarene, the carboxyl groups form dimeric or cyclic tetrameric complexes via intermolecular H-bonds. The conformation of the cone persists, but there is a mutual influence of H-bonds along the upper and lower rims of the thiacalix[4]arene molecule. The structure with dimer H-bonds between carboxyl groups is 31.9 KJ/mol less preferable than the conformation with tetramer cyclic H-bonds for 1-AdCOOHTC4A. Comparison of the absorption band of νOH alcohol hydroxyl groups in the IR spectra of 1-AdCOOHTC4A at 3377 cm−1, with the corresponding band of 1-AdTC4A at 3372 cm−1, suggests that the presence of the second system of H-bonds of carboxyl groups in the first molecule does not affect the H-bond of alcohol hydroxyl groups.

The IR and Raman spectra of p-(3-carboxymethyl-1-adamantyl)calix[4]arene (1) and tetrapropoxy-p-(3carboxymethyl-1-adamantyl)calix[4]arene (2) were studied. In the IR spectra of crystals and solutions of calixarenes, there is no band of stretching vibrations of free OH groups. In the IR spectrum of compound 1 in the crystalline state, an intense wide band is observed at 3187 cm & minus;1. In the IR spectrum of a dilute solution in CCl4, this band shifts to 3118 cm & minus;1. The carboxyl groups form cyclic dimer or tetramer complexes.& nbsp; The formation of dimers of carboxyl groups is more favorable than for cyclic tetramers. The energy difference is 33.8 and 53.0 kJ/mol in compounds 1 and 2, respectively. The calculation showed that molecules 1 and 2 of dimeric and tetrameric complexes assume the cone conformation. The molecules of compound 2 are in the cone conformation even in the absence of hydrogen bonds along the lower rim.& nbsp; (c) 2021 Elsevier B.V. All rights reserved.

The effects of the concentration and functionalization of carbon nanotubes on the degree of conversion of epoxy groups in epoxy-amine compositions based on ED-20 epoxy oligomer and the PEPA curing agent are studied. It has been shown that increasing the concentration of functionalized carbon nanotubes (CNT) from 0 to 0.5 % increases the degree of conversion of the epoxy groups during curing at a room temperature. Further increase in concentration CNT of up to 1 % does not effect on the reaction kinetics. For native CNT not established such a relationship. Explains such a pronounced effect on the f-CNT aminolysis reaction kinetics and ultimate degree of conversion of epoxy groups, apparently, the catalytic effect of oxygen-containing groups (hydroxyl, carboxyl, and others) grafted to the surface of CNTs and their direct involvement in the reaction. By optical microscopy showed that the size of the agglomerates of nanotubes were substantially higher in the native systems than in the system with the functionalized nanotubes. These results may be important for the development of creation of epoxy composites modified by nanoparticles.

The IR spectra of p-(3-carboxy-1-adamantyl)-calix[4]arene (AdC4A) were studied. Using IR spectroscopy, it has been shown that in calixarene in dilute solution in CCl4, there was no free hydroxyl absorption band. The hydroxyl group band was characterized by a very low frequency, which indicates a strong intramolecular hydrogen bond on the lower rim of the calixarene molecules. On the upper rim of the calixarene, the carboxyl groups form cyclic dimer or tetramer complexes via intermolecular hydrogen bonds. The cone conformation persists, but there is a mutual influence of the hydrogen bonds along the top and bottom rims of the calixarene molecule. The structure with dimeric hydrogen bonds between the carboxyl groups is 16.5 KJ/mol more preferable than the structure with tetrameric cyclic hydrogen bonds for AdC4A. The reactivity depends on the type of association on the upper rim, whether these are hydrogen-bonded dimers or cyclic tetrameric association.

The creation of materials with high strength, durability, and biostability is a relevant development area for modern building materials science. This paper studies a number of modified cement compositions obtained by the mechanical activation of the vortex layer device binder. A superplasticizer and carbon nanotubes of various structure and functionality were used as modifiers. The cement composition was determined in a laboratory kinetic unit designed by the authors. It is found that the biostability coefficient values of the cement composition samples obtained by the mechanical activation of the binder and with the introduction of the superplasticizer are 13% higher than the same control composition value. It is indicated that the additional introduction of single and multilayer carbon nanotubes increases the cement composition biostability by 50%. It is found that the highest biostability values are observed in cement compositions obtained by the mechanical activation of the binder with the combined introduction of the superplasticizer and multilayer (MWCNT) "Graphistrength" carboxyl-functionalized (-COOH) nanotubes. The x-ray phase analysis method found that during the exposure of the cement composition samples under study in a model citric acid medium, the portlandite is carbonized with calcite formed which causes a decrease in the compression and bending strength of the cement composition samples. (C) 2020 Elsevier Ltd. All rights reserved.

The increasing need of raw materials is one of the drivers for further development of inorganic binders, including alkali-activated cements. This research focuses on the study of the potential suitability of raw and calcined marl with a high calcite/aluminosilicates ratio as a supplementary material for alkali-activated blended systems using alkali-activated salg cement as an example. Marl calcined at 800 degrees C was found to be a more promising supplementary material for alkali-activated blended cements compared to raw marl. The thermal treatment at 800 degrees C results in the partial amorphization; formation of reactive Si, Al, and Ca due to the dehydroxylation of clay minerals and decarbonation of calcite. These provide the marl with the capability to form aluminosilicate hydrate gels and contribute to the mechanical characteristics of hardened activated mixed pastes. The hardened blended ground granulated blast furnace slag/calcined marl systems activated by hydrous sodium silicate and cured at room temperature had 28-day compressive strength of 27.5-40 MPa depending on the ratio of the slag/calcined marl. XRD, TG/DSC, FTIR, optical microscopy, and SEM were used to investigate the reaction products, as well as the microstructure of the activated blended pastes.

The hydrogen bonds and the conformations of calix[8]arene molecules with p-tert-butyl and p-1-adamantyl substituents were studied by infrared spectroscopy in different states. The conformations, the reactivity, the charge distribution and the IR spectra of the calixarenes were calculated by the DFT method with the PBE functional and a TZVP basis set. We compare the IR spectra of calix[8]arene molecules in the conformation of the pleated loop and the chair. The optimized geometry of the molecules reproduces the experimental X-ray data. The conformation chair is 20 kcal/mol less preferable than the conformation pleated loop. The conformation of a pleated loop is the most stable in the solid state and solution. Hydrogen bonds determine the stability of this structure. In the p-1-adamantylcalix[8]arene, stronger hydrogen bonds are realized compared to p-tert-butylcalix[8]arene. The observed IR spectra were interpreted using the calculated potential energy distribution with the quantum-chemical force constants. The theoretical absorption curves calculated for the pleated loop conformation correspond to the experimental IR spectra of the calix[8]arenes.

In this study, a mineral matrix based on hydrous sodium metasilicate (NSH5)-activated slag cement (AASC) was found to be suitable for solidification of sodium nitrate solutions with concentrations of up to 700 g/l and nitrate ion-exchange resins with volume of up to 35%. XRD, TG/DSC, FTIR, and SEM/EDS analyses were used to study the wasteforms. Increasing the nitrate solution concentration decreased the rates of hydration and structure formation process of the system GGBFS-NSH9-NaNO3 solution, the amount of the Ca-, Si-, Al-, and Mg-containing reaction products, and slightly decreased the compressive strength of the wasteforms.

Thiacalix [4]arene (TC4A), p-tert-butylthiacalix [4]arene (t-BuTC4A) and p-(1-adamantyl)thiacalix [4] arene (1-AdTC4A) IR spectra were studied. Calculated energies and IR spectra of the various conformers (cone, partial cone, 1,2-alternate, and 1,3-alternate) were compared. The cone is the most stable conformation for all studied thiacalix [4]arenes. Theoretical IR spectrum of adamantylthiacalix [4]arene molecule in the form of a cone is consistent with experiment. Classification of bands in the IR spectrum of adamantylthiacalix [4]arene has been implemented. The strength of H-bonding in the thiacalix [4] arenes depends on the type of the substituent. In the conformation of the cone cyclic system of H-bonds are implemented for all the studied thiacalix [4]arenes. Introduction of adamantyl substituents leads to convergence of oxygen atoms in molecules of thiacalix [4]arene and H-bonds are strengthened. Conformation cone of molecules of thiacalix [4]arenes does not change when heated to a temperature of 180 degrees C and dissolving in a neutral solvent. (C) 2018 Elsevier B.V. All rights reserved.

The expanding raw materials base is one of the drivers for the further development of inorganic binders, including alkali-activated cements. This research focuses on studying marl with a high calcite/aluminosilicates ratio as a geopolymer precursor, and limestone as a mineral addition to this geopolymer. The calcination of marl at 800 degrees C resulting in the formation of reactive Si, Al, and Ca due to the dehydroxylation of clay minerals and decarbonation of calcite makes marl suitable for use as a geopolymer precursor. Calcined marl activated with sodium silicate and cured at ambient temperature had a 28-day compressive strength of 34 MPa. When incorporated with 50% limestone, the compressive strength became 39.2 MPa. XRD, TG/DSC, FTIR, optical and SEM have been used to investigate the reaction products, as well as the microstructure of the geopolymer hardened pastes.

The IR spectra of p-tertbutylcalix[6]arene and adamantylcalix[6]arenes were investigated. The influence of heating and dissolution on the system of hydrogen bonds in calix[6]arenes was studied. The theoretical IR spectrum of adamantylcalix[6]arene in the conformation of a compressed cone agrees with experiment. Classification of bands in IR spectrum of adamantylcalix[6]arene was performed. Structure and strength of the H-bonding in calix[6]arenes depends on the type of substituent. In all calix[6]arenes studied, the cyclic H-bonds in the conformation of the compressed cone is realized. Under the action of adamantyl substituents, there is a convergence of oxygen atoms in the calix[6]arene molecules and the strengthening of H-bonds. Heating to a temperature of 180 degrees C and the dissolution of calix[6]arenes in neutral solvents does not lead to a change in their conformation. (C) 2018 Elsevier B.V. All rights reserved.

In this study the mineral matrix based on hydrous sodium metasilicate (NSH5) activated slag cement (AASC) was found to be suitable for solidification of borate solutions with pH 8.5-10.5 and concentration up to 200 g/L. Parameters such as setting times and compressive strength of the waste forms based on AASC and borate wastes can be influenced by the ratio of NSH5 and H3BO3 content. The dosage of 7% Na2O in the alkali activator per slag provides acceptable setting times and 28-day compressive strength of the waste forms in the range 49.7-56.1 MPa depending on pH of the borate solutions. Lowering the pH of borate solutions results in a reduced rate of setting of the fresh AASC paste, retardation in the structural formation of the hardened AASC paste, a reduced degree of hydration, and a reduction in the amount of calcium silicate hydrates and hydrotalcite. The product of AASC-based mineral matrix and simulated borate wastes interaction is ulexite (NaCaB5O6(OH)(6)(H2O)(5)). (C) 2017 Elsevier Ltd. All rights reserved.

This article describes a comparative research of IR spectra and H-bonds in the p-tert-butylcalix[6]arene (TB6) and calix[6]arene (C6). IR spectra were computed for compressed cone conformation by DFT method. The assignment of the bands in the IR spectra of the TB6 and C6 was made. The effect of the bulky tert-butyl substituents on the structure and H-bonding in TB6 was established. Our research has shown that in TB6 and C6 the cyclic H-bond is realized, which ensures the existence of a compressed cone conformation. Introduction of tert-butyl substituents in TB6 leads to hardening of H-bonds. Examination of IR spectra showed that when heated TB6 remains in a compressed cone conformation. In a molecule of TB6 and C6 oxygen atoms are in a “boat” conformation.