


Vol 48, No 4 (2016)
- Year: 2016
- Articles: 17
- URL: https://journal-vniispk.ru/0015-0541/issue/view/14595
Chemistry and Technology of Chemical Fibers
Effect of Precipitation-Bath Concentration on Rheological Properties of Polymer Systems with Wet Spinning of Fibers
Abstract
The effect of the precipitation-bath concentration on the viscoelastic properties of wet-spun polyacrylonitrile fiber was studied. The polymer system to be deformed was modeled structurally as a network of intermolecular linkages that consisted of viscous and elastic nodes and could be used to explain many physical phenomena occurring during the deformation, in particular, the known phenomenon of forming voids and vacuoles in the spun fiber. It was shown that the jet-fiber during spinning into mild baths transitioned sequentially from the viscoelastic state, initiating a pathway that formed a viscous (Newtonian) state at its end. The effect of the precipitant composition on the structure-fixation length and time for a jet in the viscous and viscoelastic states was examined.



Article
Methanol Synthesis Using Copper Catalysts Supported on CeO2−Al2O3 Mixed Oxide
Abstract
Results are given for a study of the catalytic and physicochemical properties of monometallic Cu/CeO2-Al2O3 and bimetallic Pd-Cu/CeO2-Al2O3 catalysts for the synthesis of methanol from hydrogen and carbon dioxide. The catalytic activity was determined in methanol synthesis in a gradientless reactor at 200°C and 3.5 MPa. The physicochemical properties of these catalytic systems were studied by the BET method (Brunauer−Emmett− Teller method), temperature-programmed reduction of hydrogen (TPR-H2), temperature-programmed desorption of ammonia (TPD-NH3), x-ray diffraction (XRD), and Fourier-transform IR spectroscopy (FTIR). Our results showed high activity for the palladium-promoted catalyst, which is attributed to a synergistic effect between palladium and copper as well as the formation of a PdCu alloy during activation of this bimetallic catalyst in a reducing atmosphere of 5% H2 95% Ar.



Optimal Conditions for Compaction and Monolith Production of Ultra-High-Molecular-Weight Polyethylene Reactor Powders
Abstract
A special cell (press-form) was fabricated for compaction and monolith production of UHMWPE reactor powder over broad ranges of pressure and temperature. The effect of applied pressure on the compaction and the temperature for UHMWPE powder monolith production was studied using scanning electron microscopy and FTIR spectroscopy. It was found that stable tablets of reactor powder were formed and the compaction was complete at 136 MPa for 8 min and more. The optimal temperature range for monolith production using compacted tablets of UHMWPE powder was 135-140°C.



Effect of External Factors on the Structure of Ultrathin Fibers of Poly(3-Hydroxybutyrate) and Dipyridamole
Abstract
Fibrous materials based on poly(3-hydroxybutyrate) containing the drug dipyridamole were investigated. The structural–dynamic characteristics of the materials were studied by scanning electron microscopy, differential scanning calorimetry, and ESR spectroscopy. The effect of a series of aggressive factors (temperature, water, ozone) on the structure of the poly(3-hydroxybutyrate) fibers with dipyridamole was investigated for the first time. It was established that the enthalpy of fusion of the fibers increases when dipyridamole is added. Complex relationships between the specific enthalpy of fusion of the crystallites and the molecular mobility of the radical are observed during the action of aggressive factors on the fibrous materials.



Structure and Sorption Characteristics of Nanocrystallites of Chitosan
Abstract
The structural features and thermal and sorption characteristics of nanocrystallites of chitosan, produced by hydrolysis and alcoholysis of high-molecular chitosan, were examined. The nature of the changes in the supramolecular structure and characteristics of the nanoparticles (degree of crystallinity, geometric dimensions of the crystallites, specific surface area) that are most significant in the nanocrystallites produced during precipitation of the products from homogeneous sulfuric acid hydrolysis of chitosan with NaOH solution is presented on the basis of data from thermogravimetric analysis, atomic-force microscopy, NMR relaxometry, and calculation of the sorption isotherms.



Influence of Precipitation and Conditioning Baths on the Structure, Morphology, and Properties of Cellulose Films
Abstract
The influence of precipitation and conditioning baths of various natures and compositions on the structure, morphology, and properties of cellulose-hydrate films produced by solid-state dissolution of cellulose in the direct solvent N-methylmorpholine-N-oxide was studied. The structure-morphology transformations occurring in freshly formed cellulose films due to various conditionings and their influence on the physicomechanical properties of the finished films were demonstrated and analyzed for the first time.



Study of Microcapillary Impregnation of Carbon Fibres by Epoxy Binders
Abstract
The results of experimental studies of epoxy binder filtration though carbon fibres are reported. Formation of two boundary layers of binders immediately adjoining the fibre surface, which acquire properties of Bingham solids (plastics), is shown. The volume carbon fibre content at which Bingham solids are formed is determined. Joining of outer epoxy binder layers occurs at carbon fibre content of 39-41 vol. % and of inner layers, at carbon fibre content of 47-50 vol. %.



Manufacture of Parachute Fabric with Specified Air Permeability from Aramid Yarns on Shuttleless Looms
Abstract
We have determined the optimal technological parameters for manufacture of parachute aramid fabric on looms of different designs. We have studied the effect of the basic operating parameters of the loom on the physical and mechanical properties of the fabric. We have established that the air permeability of parachute fabric can be considerably reduced due to buckling of the warp yarns when using droppers. We have worked up recommendations for manufacture of fabric with specified air permeability on a high-speed Dornier rapier loom, making it possible to improve the quality of the fabric and the productivity.



Adsorption Activity of Materials Derived from Copolymers of Acrylonitrile with Various Acid Comonomers
Abstract
A study was carried out on the adsorption of zinc ions by ion-exchange materials derived from fibrous copolymers of acrylonitrile (AN) with 2-acrylamide-2-methylpropanesulfonic acid (AMPS), acrylic acid (AA), or itaconic acid (ItA) as the ionogenic component. The adsorption activity of materials derived from poly[AN-co-AMPS] containing sulfo groups is somewhat reminiscent of the behavior of carboxyl ion-exchange resins. The amount of zinc adsorbed by materials derived from poly[AN-co-AMPS] may exceed the static exchange capacity (SEC) for sulfo groups. It was proposed that the amide groups affect the adsorption behavior of ion exchangers derived from poly[AN-co-AMPS].



Aspects of Forming the Fell of a Fabric (Narrow Fabric) Made From Mineral Threads
Abstract
We have developed a procedure for determining the position of the fell of a fabric, taking into account the accuracy in manufacture of the pivot linkages during production of fabrics made from glass and basalt threads. We have performed calculations for the mechanism for beating up the weft on a narrowfabric loom. The calculated position of the fell of the fabric is fixed using an assembly of stretcher temples and a crossbar, clamped to the loom frame.



Design Principles for Knitted Items with Bicomponent Cloths
Abstract
The properties defining the target purpose of functional clothing in addition to the construction and external appearance requirements are dominant factors in its fabrication. For example, sports apparel should even out temperature drops of the body and wick water away from it well. An analysis showed that such attire could be produced if the sides of the item were made of a different kind of thread or yarn. Items made of bicomponent cloths can economize raw material by combining different cloths in a single item. The material outlays for the items could be reduced by using bicomponent cloths in several of their parts.



Device for Automated Temperature Control of the Spinning Zone During Cone Drawing of Fluoride Optical Fibers
Abstract
A method for remote automated temperature control of the spinning zone during production of fluoride optical fibers by the two-color process is proposed. An electrical diagcphram of a spinning-zone temperature sensor that uses the proposed method is developed.



Fibre Composite Materials
Market for Carbon Fibres and Composites Based on them. A review
Abstract
The basic trends in development of market for carbon fibres and their composites are reviewed on the basis of published reports of experts from various organizations. Data on volumes of production and consumption of products, major manufacturers, areas of application, and outlooks for the near and far future are presented.



Materials Science
Strengthening of Rusar NT Fibre by Electromagnetic Treatment
Abstract
The results of electromagnetic treatment (EMT) of Rusar NT aramid fibre, which increased the ultimate strength and elasticity modulus by 8-10%, are reported. The theoretical possibility of enhancing strength properties of Rusar NT fibre up to 20% by EMT is shown. The measurements were systematized by cluster analysis. It is suggested that the hydrogen bond is strengthened upon EMT, which ultimately leads to improvement in strength properties of Rusar NT fibre.



Research Methods
IR Spectral Study and X-Ray Structural Analysis of the Supramolecular Structure of Cellulose Powder
Abstract
IR spectroscopy and x-ray structural analysis were used to study the supramolecular structure of cellulose powders obtained by the hydrolytic decomposition of bleached coniferous cellulose using mineral acids and its mercerized form. IR spectroscopy was used to establish the nature of the intermolecular bonds in the cellulose powder macromolecules. The Rietveld refinement was used to determine crystallinity and size of coherent scattering regions as well as to calculate the lattice periods of the crystalline component of these materials.



Control Systems for Production Processes
Upgrading Automatic Control of a Complex Electromechanical System for Production of Synthetic Yarns and Nonwoven Materials
Abstract
We have developed a device simulating the process of spinning, conveying, and winding synthetic yarns and nonwoven materials. We propose upgraded automatic control of a complex electromechanical system with conveyor and winding devices, ensuring energy-efficient conditions and an increase in productivity of the equipment as a result of partial upgrading of individual units and mechanisms.



Erratum
Erratum to: Rigidity of Glass, Carbon, and Organic Yarns of Special-Purpose Fabrics


