Технико-технологические инновации. Рубрика в журнале - НБИ технологии
Статья научная
The quantitative interpretation of the extreme dependence of elastic modulus on the composition of poly(ethylene terephthalate)/poly(butylene terephthalate) blends has been proposed. At this, the authors apply the basics of the percolation theory and fractal analysis. It has been shown that the extreme increase in elastic modulus is due to the corresponding growth of shear strength of blends components during the autohesional bonding. It is noted that the micromechanical models do not give the adequate description of the indicated effect.
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The deformability of polycarbonate / poly (ethylene terephthalate) blends
Статья научная
It has been shown that the extreme enhancement of strain at break for blends polycarbonate/poly(ethylene terephthalate) blends is due to the corresponding structural changes of the indicated blends, which are characterized by their structure fractal dimension variation. The blends deformability rise can be achieved by enhancement of either Flory-Huggins interaction parameter, or shear strength of their autohesional contact. The transparence threshold of macromolecular coils achievement results in sharp reduction of strain at break, i.e. its decrease practically up to zero.
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Статья научная
As it is known, any real fractal object can be simulated as a bulk or surface fractal. In the first case the structure fractality is extended to the entire volume of the object and in the second one - to its surface. For nanocomposites, the matrix of which makes up polymer poly(ethylene terephthalate)/poly(butylene terephthalate) blend, the fractal dimensions of both structure and surface of ring-like formations of nanofiller (multiwalled CNT) were calculated. It has been found out that in case of their notion as bulk fractals, i.e. matrix polymer penetration in ring-like formations internal regions, the strong enhancement of the nanocomposites melt viscosity is observed and in case of surface fractals this parameter is independent on nanofiller contents.
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Статья научная
The effect of different doses of synthetic antioxidant b-(4-hydroxy-3,5-ditertbutylphenyl), propionic acid (phenosan) and savory essential oil on the development of spontaneous leukemia was studied. The drug efficiency was determined from the survival curves, animal life spans, and the incidence of leukemia. Phenosan is characterized by clear antitumor activity in therapeutic (10-4 mol/kg) and ultra-low (10-14 mol/kg) doses. The dose of 10-14 mol/kg increases the life span. The savory essential oil in low doses mixed with drinking water (150 ng/ml) or food (2,5 mg/g) increased the average lifetime of mice by 20-35 %. The low doses of these drugs seem promising as preventive drugs.
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The influence of melafen on structural properties of phospholipid membranes
Статья научная
The paper studies the effect of aqueous solutions of melamine salt of phosphonic acid (Melafen), used in crop production, on structural and thermodynamic properties of phospholipid membranes. The multilamellar liposomes formed from individual synthetic dimyristoylphosphatidylcholine (DMPC), or natural phospholipid mixture (egg lecithin) was studied by differential scanning microcalorimetry (DSC) and small-angle X-ray scattering (SAXS). The method of DSC was used to appraise the influence of Melafen aqueous solutions (10-17 M to 10-3 M) on thermodynamic parameters of lipid melting (temperature, enthalpy and cooperation of phase transition) in suspension of liposomes formed from DMPC. On the basis of DSC data it was concluded that the microdomain structural organization of DMPC membranes was altered by Melafen aqueous solutions as polymodal type. We did not reveal by the SAXS method any noticeable integral structural changes in membranes of egg lecithin in multilamellar liposomes as well as in their stacking parameters (period and degree of order) in Melafen aqueous solutions (10-21 M to 10-6 M). This range of Melafen concentrations is wider than that used in crop production. Relying on the results of this work it can be inferred that microdomain structure of membranes composed of individual neutral phospholipids is changed in Melafen aqueous solutions at the wide concentration range of Melafen. At the same time, Melafen does not affect the overall structure of lipid membranes composed of a natural phospholipid mixture.
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Статья научная
It has been confirmed that properties of polymer materials are encoded by the structure at the molecular level. The impact toughness of poly(ethylene terephthalate)/ poly(butylene terephthalate) blends is controlled by macromolecular coils interactions, which are reflected on the structure of their fractal dimension. It has
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The investigation of thermal power characteristics of wood pulp
Статья научная
To study the heating value of wood we used integrated thermal analysis. We have studied the aspen wood aged 10 years. For sample 3 (bark), which is characterized by the largest coke residue, the heterogeneous oxidation process occurs most rapidly. The thermal analysis shows that the pattern of the cortex has the highest heating value.
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The method for lifetime estimation through the mechanical properties in tension
Статья научная
The method for prediction of Paris' curve shape through the results of tensile test is suggested. For this purpose the author developed non-direct method for determination of Kth and Kfc and corresponding to them da/dN values. The relationship between Kth and b/y ratio was found. The correlation Kfc(KIc) was also shown. It makes possible to estimate lifetime of different structures with cracks under cyclic loading.
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The method of increasing the thermostability of filled polymers
Статья научная
The individual contribution of stabilizers and fillers into the increase of thermal stability of a polymer-matrix of composite materials at their joint presence in the composite is estimated in this paper. The increase of thermal stability of polypropylene composites in the process of pre-saturation of the surface of fillers by thermal stabilizers compared to their individual introduction into the polymer is determined. A method of saturation of the surface of fillers by stabilizers is proposed. The mechanism of a prolonged and direct action of stabilizers desorbing from the surface of the filler is explained. It leads to the increase of the thermal stability of stabilized filled polypropylene compositions obtained by the proposed method by 10-40 % in comparison with the traditional one. It simultaneously reduces the amount of used stabilizers in 1.25 times.
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The reinforcement of particulate-filled polymer nanocomposites by nanoparticles aggregates
Статья научная
The applicability of irreversible aggregation model for theoretical description of nanofiller particles aggregation process in polymer nanocomposites has been shown. The main factors, influencing nanoparticles aggregation process, were revealed. It has been shown that strongly expressed particulate nanofiller particles aggregation results in sharp (in about 4 times) formed fractal aggregates real elasticity modulus reduction. Nanofiller particles aggregation is realized by cluster-cluster mechanism and results in the formed fractal aggregates density essential reduction, that is the cause of their elasticity modulus decrease. As distinct from microcomposites, nanocomposites require consideration of interfacial effects for elasticity modulus correct description in virtue of a well-known large fraction of phases division surfaces for them.
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Ultrathin poly (3-hydroxybutyrate) fibers: structure and dynamic characteristics
Статья научная
Structural and dynamic analysis based on combined thermophysical and molecular-mobility measurements via spin-probe ESR spectroscopy has been applied to films and fibrous matrixes based on poly(3-hydroxybutyrate). The dynamic behaviors of partially crystalline samples during deformation under conditions of electrospinning and cold rolling have been compared. The comparative results of the complex investigation of films and ultrathin fibers in the poly(3-hydro-xybutyrate) matrix have shown that the electromechanical action leads to additional crystallization of the crystalline regions, spherulites, and lamellas in the polymer. The changes in the crystalline phase of the polymer are accompanied by an increase in the packing density of macromolecules in the intercrystalline space. With the use of the spin-probe ESR method, the effect of water and the oxidant ozone on the morphology of the amorphous phase of poly(3-hydroxybutyrate) ultrathin fibers has been determined. The measurements of the dynamics of spin-probe rotation in samples before and after cold rolling have shown that the additional orientation of poly(3-hydroxybutyrate) spherulites in a mechanical field results in stabilization of amorphous regions more resistant to the aggressive effects of ozone.
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Valve cam design using numerical step-by-step method
Статья научная
This article studies the numerical step-by-step method of cam profile design. The results of the study are used for designing the internal combustion engine valve gear. This method allows to profile the peak efficiency of cams in view of many restrictions, connected with valve gear serviceability and reliability.
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Ways of regulation of release of medicinal substances from the chitosan films
Статья научная
The article studies the chitosan films obtained by applying acetic acid and two antibiotics of cephalosporin and aminoglycoside type. It investigates the possibility of their transport properties regulation in the sphere of medicines manufacture. This regulation can be carried out by films with thermal modification implying the heating of formed films at the temperature of about 120 °C and reaction with sodium dodecyl sulphate. The article shows that the antibiotics release from films will be determined by the amount of antibiotics connected with chitosan by hydrogen bonds, on the one hand, and by the state of the polymer matrix, on the other hand.
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Статья научная
Novel, previously unknown, wide pore poly(vinyl alcohol) cryogels (PVACGs) have been prepared through the cryotropic gelation approach, when water-PVA-gum Arabic (GuAr) ternary liquid systems were used as feeds. The following set of conditions necessary for obtaining wide-porous, permeable for a water flow, and, simultaneously, mechanically strong enough PVACGs was established: the total concentration of gelling component - PVA (MW of 86 kDa) and non-gelling polymer - GuAr (MW of ~650 kDa) should exceed ~14 wt. %, GuAr/PVA ratio should be near 1 : 1 (w/w), and the feed’s pH should be within the range of ~5-11. The phase diagrams for the water-PVA-GuAr ternary liquid systems at pH 5.3 and 10.0 have demonstrated that such “optimum” compositions are in the vicinity of the rectilinear diameters of the respective diagrams, and that the limit of GuAr solubility in the PVA-rich phase is small. In such cases this GuAr fraction strongly binds with PVA, especially under alkaline conditions, within the forming gel phase of heterophase PVACG. The light microscopy studies revealed the presence of at least three distinct kinds of pores in these cryogels. Firstly, there are interconnected channel-like gross pores with cross-section of 100-200 µm which are the replicas of continuous GuAr-rich phase in the two-phase polymeric systems appearing due to the liquid-liquid phase separation in the ternary water-PVA-GuAr system. The second type is represented by isolated roundish large pores ca. 10-70 µm in diameter being the replicas of GuAr-rich phase dispersed as liquid droplets in the PVA-rich phase. And the third type is represented by the smaller rounded pores ~1-5 µm in diameter being the replicas of ice polycrystals. Such sophisticated “poly-porous” morphology of the studied PVA cryogels is their unique feature distinguishing them from other known PVA cryogels.
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Статья научная
В статье в свете теории групп Ли предложены критерии разрешимости задач синтеза аварийной стабилизации. Данные критерии позволяют строить алгебры Ли для подобного класса задач.
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Анализ увеличения пропускной способности линий сверхвысокого напряжения
Статья научная
Проведен сравнительный анализ линий сверхвысокого напряжения разных классов напряжения с использованием различных марок проводов. Сделаны выводы о целесообразности применения различных вариантов линий исходя из проведенного технико-экономического расчета.
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Базальтофибробетон - технология будущего
Статья научная
Дисперсное армирование бетона с использованием композитной фибры, производимой из расплава базальтовых пород, обеспечивает значительные физико-механические преимущества базальтофибробетона (БФБ).
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Биопластики на основе термопластов
Статья научная
С ростом мирового производства полимерных материалов (ПМ) все более обостряются проблемы защиты окружающей среды от полимерных отходов, которыми являются использованные изделия из ПМ и отходы их производства. В статье дан анализ известных подходов к решению этих проблем с точки зрения эффективности.
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Влияние рН, природы и концентрации электролитов на флотационное извлечение дисперсной фазы эмульсии
Статья научная
Выявлены и рассмотрены основные факторы влияния рН, природы и концентрации электролитов на эффективность очистки воды от нефтепродуктов. Проанализированы данные об остаточном содержании нефтепродуктов при очистке вод с различным содержанием электролитов. Описан флотационный процесс очистки с использованием смешанного реагента (СР).
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Влияние регулировочных параметров на токсичность отработавших газов дизеля воздушного охлаждения
Статья научная
В статье дана оценка подходов к нормированию выбросов отработавших газов дизельных двигателей, предназначенных для установки на внедорожную технику в странах Северной Америки, Западной Европы, Японии, Китая, Африки и России и др. Приведены экологические показатели двигателя 8ЧВН15/16, выполнена их оценка на соответствие действующим в настоящее время стандартам.
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