scholarly journals Kinetics of structure formation of a composite mortar with nano-additives based on aluminium

2020 ◽  
Vol 161 ◽  
pp. 01099
Author(s):  
S.Yu. Efremova ◽  
M.I. Panfilova ◽  
N.I. Zubrev ◽  
O.V. Novoselova
Keyword(s):  
Structure Formation ◽  
Temporal Evolution ◽  
Initial Period ◽  
Control Sample ◽  
Injection Efficiency ◽  
Evolution Of Structure ◽  
Nano Additives ◽  
Kinetics Of

This paper discusses the possibility of using aluminum-containing nano-additives as structure modifiers of composite mortar in order to ensure safety and durability of rubble foundation. Higher injection efficiency can be achieved by integrating the composite mortar into the foundation body. The temporal evolution of structure formation in composite mortar with various contents of boehmite and aluminosilicate nanotubes (ANT) was studied. The optimal concentrations of additives were determined at which the rate of structure formation reaches its maximum. It was revealed that ANT additives accelerate the hardening time of the composite mortar by 1.3 times in comparison with boehmite additives. The greatest impact on accelerating the structure formation in the initial period is achieved by adding 0.125% aluminosilicate tubes to the mass of cement. It was found that in this case, the duration of flowability loss of the composite mortar is reduced by a factor of three compared with that of the control sample.

The mechanism of the anionic coordination polymerization of isoprene

1980 ◽  
Vol 45 (9) ◽  
pp. 2391-2399 ◽  
Author(s):  
Miroslav Kašpar ◽  
Jiří Trekoval
Keyword(s):  
Chromatographic Method ◽  
Initial Period ◽  
Reaction Scheme ◽  
Polymerization Kinetics ◽  
Coordination Polymerization ◽  
Initial Concentration ◽  
The Cross ◽  
Gas Chromatographic Method ◽  
Kinetics Of

The polymerization kinetics of isoprene (2-methyl-1,3-butadiene) in benzene with butyllithium as the initiator was investigated by the gas chromatographic method. After completion of the initial period of the reaction, its order with respect to the initial concentration of initiator is negative at the concentrations of the latter between 0.01 and 0.25 mol/l, and positive at higher concentrations. A reaction scheme has been suggested with respect to the "cross" association of butyllithium and of the "living" oligoisoprene.

Vulcanization of Rubber in the Presence of N,N-Diethyl-2-Benzothiazolylsulfenamide as Accelerator

1960 ◽  
Vol 33 (2) ◽  
pp. 361-372 ◽  
Author(s):  
B. A. Dogadkin ◽  
O. N. Beliatskaya ◽  
A. B. Dobromyslova ◽  
M. S. Feldshtein
Keyword(s):  
Induction Period ◽  
Maximum Rate ◽  
Initial Period ◽  
Pure Oxygen ◽  
Butadiene Rubber ◽  
Sulfur Vulcanization ◽  
Analogous Manner ◽  
Chemical Crosslinks ◽  
Main Period ◽  
Kinetics Of

Abstract 1. The vulcanization of rubber in the presence of N,N-diethyl-2-benzothiazolylsulfenamide is characterized by an S-shaped curve for the addition of sulfur with an initial induction period in the reaction. The modulus and number of crosslinks are changed in an analogous manner to the structure of the vulcanizate. 2. The energy of activation of the addition of sulfur in the initial period is equal to 30 kcal per mole as against 14 kcal per mole in the main period. 3. The induction period is increased if the sodium-butadiene rubber is purified from alkali. 4. Molecular oxygen present in the compound being vulcanized decreases the induction period and increases the rate of the addition of the sulfur in the main period. An induction period is not observed when vulcanization is carried out in an atmosphere of pure oxygen. 5. The interaction of N,N-diethyl-2-benzothiazolylsulfenamide with rubber (in the absence of sulfur) at vulcanization temperatures is accompanied by the formation of MBT, diethylamine, and the addition of the elements of the accelerator to the rubber. The kinetics of this process were studied. 6. The interaction of N,N-diethyl-2-benzothiazolyl sulfenamide with rubber leads to the formation of chemical crosslinks between the molecules of rubber (the effect of vulcanization). 7. The change of N,N-diethyl-2-benzothiazolyl sulfenamide under the conditions of normal sulfur vulcanization has the same character as in the interaction of it with rubber. The kinetics of the formation of MBT have a maximum which coincides with the maximum rate of the addition of sulfur to the rubber. 8. A mechanism is presented for the vulcanization and acceleration actions of N,N-diethyl-2-benzothiazolyl sulfenamide which provides for the extraction of hydrogen by the accelerator radicals from the molecular chains of the rubber with the formation of MBT, diethylamine and polymer radicals which are able to interact with the sulfur.

Research of drying kinetics of prepared wheat flour

2021 ◽  
Vol 9 (16) ◽  
pp. 212-220
Author(s):  
Liubomyr Khomichak ◽  
◽  
Inha Kuznietsova ◽  
Svetlana Vysotska ◽  
Sergiy Tkachenko ◽  
...  
Keyword(s):  
Moisture Content ◽  
Wheat Flour ◽  
Raw Materials ◽  
Control Sample ◽  
Raw Material ◽  
Convective Drying ◽  
Kinetic Dependence ◽  
Vital Functions ◽  
Kinetic Coefficients ◽  
Kinetics Of

Introduction. Processing of grain raw material with influence on starch or albumens by application of heat treatment creates the variety of functional properties of a product and is perspective in the modern terms vital functions of man. Research methods and methods. The flour obtained from wheat of the Ascanian wheat and from wheat of the soft varieties: Sophia ("sweet wheat"), Blond (soft) and Chornobrova (enriched with micro- and macronutrients) were used in the study. Thermal modification of flour samples was carried out in a convective manner. The control sample for determining the quality indicators is obtained in industrial conditions, extruded wheat flour produced by LLC "AS groups, LTD". Research results. The obtained kinetic dependence shows the gradual loss of moisture standards with different speed which accordingly influences on duration of drying. The moisture content of the drying agent most affects the intensity at the initial stage of the constant drying rate. With an increase in the moisture content of the coolant, the period of constant drying increases and the amount of evaporated moisture increases during this period. With the subsequent removal of moisture from raw materials, the degree of influence of this parameter on the intensity decreases. The nature of the drying curves is the same and the recommended process for obtaining modified flour is the process duration of 300 minutes or 5 hours. It was determined microscopically, that the samples of dried wheat flour have a purpose and are partially destroyed by starch granules and amorphization of biocomposite materials. Based on the data on the kinetics of drying flour samples, the kinetic coefficients and values of the critical moisture content for drying wheat flour were calculated, which is 1.18-1.30 %. It was determined that for the sensorial indicators the obtained samples have indicators characteristic of the varietal characteristics of wheat, from which the flour was taken. In terms of physical and chemical parameters, the modified wheat flour samples are not inferior to the well-known industrial sample of extruded flour. Conclusions. Use of flour, obtained from the wheat with different correlation of amilose and amylopectin, positively influences on a technological process and allows to extend the assortment of modified starch products, and accordingly, food products. Kinetics of the convective drying standards of the flour is investigated. Researches showed that a it is physically modified flour obtained from the different sorts of the soft wheat is not inferior in quality to the extruded wheat flour.

scholarly journals FEATURES OF QUANTITATIVE MEASUREMENTS OF THE DYNAMIC MODULE OF ELASTICITY OF BINDERS IN OPTIMIZATION OF PRODUCTION TECHNOLOGY SEROGYPSUM COMPOSITE

2021 ◽  
pp. 86-92
Author(s):  
V.I. Tarasevych ◽  
◽  
Yu.G. Gasan ◽  
V.B. Dolgoshey ◽  
◽  
...  
Keyword(s):  
Time Dependence ◽  
Structure Formation ◽  
Elastic Properties ◽  
Physicochemical Characteristic ◽  
Resonance Method ◽  
Acoustic Resonance ◽  
Mechanical Action ◽  
Bending Vibrations ◽  
Damping Decrement ◽  
Kinetics Of

The paper considers the issues of studying the structure formation of binders during hardening to determine the optimal moments of mechanical action on gypsum concrete specimens, which makes it possible to optimize the technology of their impregnation with sulfur melt. The time dependence of the elastic modulus of a hardening, binder is its important physicochemical characteristic, since it is used to objectively identify the stages of structure formation, to simulate the processes occurring at each of the stages. It is noted that the method of acoustic resonance of bending vibrations, in the case of hardening binders, needs correction with respect to the measurement technique and interpretation of the results obtained. The kinetics of the resonance frequency of a sample consisting of a rigid cell and a dispersion poured into it is a function of the elastic properties of the cell, the dispersion itself, the contact zone of the dispersion with cell and therefore cannot be used for either qualitative or quantitative analysis of the kinetics of hardening. Taking into account the elasticity of cuvette is necessary to obtain reliable information. It has been established that in the presence of shrinkage or significant expansion of the binder, the study of structure formation by the resonance method should be carried out in plastic cuvettes. Regardless of shrinkage, the use of a cuvette requires compulsory consideration of its elastic properties. It is advisable to objectively distinguish the stages of structure formation on the basis of the kinetics of not the dynamic modulus of elasticity itself, but the rate of its change. The time dependence of the logarithmic damping decrement is also an important characteristic of the concrete structure. The studies carried out make it possible to obtain serogypsum composites with the necessary performance characteristics and to manufacture elements of architectural décor, wall fencing products of increased aesthetics, durability and reliability from them.

scholarly journals Estimation of anti-icing properties of coatings

2019 ◽  
Vol 135 ◽  
pp. 01009
Author(s):  
Valentina Loganina ◽  
Svetlana Kislitsyna
Keyword(s):  
Initial Period ◽  
Wetting Angle ◽  
Silicone Resin ◽  
Thermal Imager ◽  
Freezing Front ◽  
Properties Of Coatings ◽  
Metal Structures ◽  
Wetting Hysteresis ◽  
Inclined Surface ◽  
Kinetics Of

The proposed composition for anti-icing coating of metal structures. The composition contains as the filler used aerosil brand R 972 with a density of 2360 kg / m3, particle size of 16 nm and a specific surface 12000 m2 / kg. Silicone resin SILRES® MSE 100 with a 10% concentration was used as a binder. The degree of hydrophobicity was estimated by the value of the wetting angle. In order to characterize the anti-icing properties of the coatings, we used the static and dynamic (advancing and retreating) wetting angle, as well as wetting hysteresis, for which we measured the angles of leakage, and the angles of drift from. Studies of the dynamics of freezing drops on the surface were performed using a TESTO 875-1 thermal imager. It is shown, that the hysteresis of wetting of the superhydrophobic surface based on the developed composition is 3.7 degrees. The critical angle of rolling drops of water from an inclined surface is determined. In the study of the kinetics of freezing of a drop of water on a metal surface, an uneven distribution of temperature on the surface of a drop of water is observed. The process of freezing drops is multistage. In the initial period, there is a transfer of heat from the surface to a drop of water. This stage is followed by the process of freezing the drop, which is manifested in the movement of the freezing front from the substrate upwards.

scholarly journals The effect of hypermethylation on the functional properties of transfer ribonucleic acid. Formation of aminoacyl-transfer-ribonucleic acid

1969 ◽  
Vol 114 (2) ◽  
pp. 429-435 ◽  
Author(s):  
David J. Pillinger ◽  
John Hay ◽  
Ernest Borek
Keyword(s):  
Amino Acids ◽  
Ribonucleic Acid ◽  
Control Sample ◽  
Transfer Rna ◽  
E Coli ◽  
Functional Sites ◽  
The Individual ◽  
Almost All ◽  
Aminoacyl Transfer ◽  
Kinetics Of

1. The ability of chemically hypermethylated Escherichia coli B transfer RNA to accept 19 amino acids was studied and the results were compared with those obtained with a control sample of E. coli B transfer RNA incubated under similar conditions in the absence of methylating agent. 2. There is a marked decrease in the ability of the modified transfer RNA to accept amino acids in almost all instances. 3. The acceptance of cysteine appears to be unique in that it is enhanced in the hypermethylated transfer RNA. 4. More detailed studies on the kinetics of acceptance for six amino acids is presented, emphasizing the variation in response of the individual amino acids. 5. Increasing hypermethylation causes a progressive decrease in the amino acid acceptance. 6. The results are discussed in terms of methylation at functional sites within the transfer RNA and possible conformational alterations to the structure of the macromolecule.

scholarly journals Modelling Water Absorption in Micronized Lentil Seeds with the Use of Peleg’s Equation

2019 ◽  
Vol 12 (1) ◽  
pp. 261
Author(s):  
Izabela Kuna-Broniowska ◽  
Agata Blicharz-Kania ◽  
Dariusz Andrejko ◽  
Agnieszka Kubik-Komar ◽  
Zbigniew Kobus ◽  
...  
Keyword(s):  
Sustainable Development ◽  
Water Absorption ◽  
Absorption Rate ◽  
Initial Period ◽  
Infrared Emission ◽  
Heating Time ◽  
Infrared Irradiation ◽  
Pre Treatment ◽  
Peleg’S Equation ◽  
Kinetics Of

The aim of the paper was to investigate the effect of infrared pre-treatment on the process of water absorption by lentil seeds. The paper presents the effects of micronization on the process of water absorption by lentil seeds. As a source of infrared emission, 400-W ceramic infrared radiators ECS-1 were used. The seeds were soaked at three temperature values (in the range from 25 to 75 °C) for 8 h, that is, until the equilibrium moisture content was achieved. Peleg’s equation was used to describe the kinetics of water absorption by lentil seeds. The results were compared with those obtained in the process of soaking crude seeds. On the basis of the conducted research, it was found that the infrared pre-treatment contributed to a substantial increase in the water absorption rate in the initial period of soaking lentil seeds (especially at 25 °C). Infrared irradiation can be an effective method for intensification of lentil seed hydration at an ambient temperature. It should be assumed that, in accordance with the principles of sustainable development, shortening the heating time will significantly reduce the energy consumption and cost of processing lentil seeds.

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