Laboratory instrument for accelerated determination of thermo-oxidative resistance of fibres

Conclusions A rapid method has been developed for determining the thermo-oxidative resistance of a fibre.An electrical laboratory instrument has been devised for determining the specific thermo-oxidative resistance of fibres in air over a wide temperature range (200–1500°C).Translated from Khimicheskie Volokna, No. 5, pp. 59–60, September–October, 1989.     

The effect of density on the limits and regularities of spin combustion of titanium in nitrogen

A region of spin combustion in the coordinate system nitrogen-pressure (100–1800 torr)-burning sample-density (2.0–3.3 g/cm ³) has been determined experimentally. The effect of density on the spin combustion characteristics (velocity, frequency, and step) has been studied at various nitrogen pressures. A transition of the spin mode of combustion to stationary with decreasing burning velocity has been observed for the first time.Translated from Fizika Goreniya i Vzryva, Vol. 32, No. 1, pp. 53–57, January–February, 1996.     

Theoretical and experimental foundation for the possibility of a combined process of drying and conditioning viscose fibres

Conclusions The possibility of using a theoretical probability model equation for predicting values of water vapor sorption at elevated temperature for high-modulus viscose fibres has been shown.It has been shown that at a drying agent temperature of 80–100°C and a relative humidity of 70%, a fibre moisture content of 11–13% is attained, which corresponds to conditioned humidity.Translated from Khimicheskie Volokna, No. 5, pp. 42–43, September–October, 1988.     

Rheological properties of mixtures of polycapromaide with hydroxyethylated products

Conclusions The effect of ethoxylated products on the rheological properties of polycaproamide has been investigated.It has been found that polyethylene glycols having a molecular weight of 3000–5000, and Synthanol and Stearox, exert the least effect in changing the rheological properties of polycaproamide.The fundamental applicability of using ethoxylated products for the modification of Kapron fibres has been demonstrated.Translated from Khimicheskie Volokna, No. 1, pp. 23–25, January–February, 1984.     

High-temperature electrochemical synthesis of carbides, silicides and borides of VI-group metals in ionic melts

Possible systems and conditions have been determined for the electrosynthesis of carbides, silicides and borides of chromium, molybdenum and tungsten on the basis of thermodynamic analysis of chemical and electrochemical reactions involved in high temperature electrochemical synthesis. Electrosynthesis of powdered molybdenum and tungsten carbides has been carried out under thermodynamic conditions from halide–oxide, under excess CO₂ pressure, and tungstate–molybdate–carbonate melts. Electrosynthesis of powdered silicides and borides of chromium, molybdenum and tungsten has been realized under kinetic conditions. Oxide and halide–oxide electrolytes have been developed for the electrodeposition of molybdenum and tungsten carbide coat ings.     

Aspects of making a superconducting yttrium ceramic by self-propagating high-temperature synthesis

Macrokinjetic features are considered for the combustion in oxygen of BaO₂–Cu–Y₂O₃ mixtures, which produces the high-temperature superconductor yttrium barium cuprate YBa₂Cu₃O_7–x. Studies have been made on how the initial temperature affects the combustion temperature and rate, and the critical temperature for self-ignition has been determined. Ultrasonic activation of the initial powders has an advantageous effect on the product quality. Thermal analysis has been applied to the activated mixtures, which indicates the reason for the rise in burning wave propagation rate and increase in conversion to the superconducting phase.Chernogolovka. Translated from Fizika Goreniya i Vzryva, Vol. 29, No. 2, pp. 62–67, March–April, 1993.     

Preparation of polyacrylonitrile fibre by spinning into organic baths

Conclusions -- The spinning of polyacrylonitrile copolymers into organic baths containing dimethyl sulfoxide and isopropyl alcohol has been investigated. It has been found that the optimum DMSO:IPA ratio in the precipitation bath is 60:40% by wt..-- It has been discovered that the strength of the spun yarn is higher the lower the jet stretch.-- The effect of temperature on orientation stretch ratio has been studied. It has been shown that the optimum temperature for heat stretching of PAN yarn lies in the range 155–160°C.-- The dimethyl sulfoxide content of yarn has been determined by technological transitions. In the final yarn it does not exceed 0.3–1.2% by wt.VNIIPV. Translated from Khimicheskie Volokna, No. 3, pp. 15–16, May–June, 1991.     

Two-stage method of synthesizing polyanthanthroylenebenzimidazole and preparation of a fibre based on it

Conclusions Polyanthanthroylenebenzimidazole has been prepared by a two-stage method. Some principles have been studied, and optimum conditions have been established for the first stage of the synthesis — preparation of the prepolymer.The possibility of cyclizing the prepolymer to polyanthanthroylenebenzimidazole has been demonstrated.Model yarn specimens have been prepared and a preliminary evaluation of their properties has been given.Translated from Khimicheskie Volokna, No. 1, pp. 29–32, January–February, 1987.     

Filtration of highly-viscous viscoses at elevated temperatures

Conclusions An equation has been obtained for estimating the change in duration of filter working cycles on change in viscosity of the viscose for the case of filtration at a constant rate.It has been shown that by increasing the viscose temperature to 30–35°C it is possible to increase the duration of a filter cycle by a factor of 1.5 to 2.5.Translated from Khimicheskie Volokna, No. 2, pp. 33–34, March–April, 1986.     

Mechanism of the thermal transformations of polyacrylonitrile fibres in oxidation

Conclusions 1. The mechanism of the physicochemical transformations of PAN fibres which take place in an atmospheric oxygen medium at 200°C has been studied, and the time intervals for their occurrence have been established.2. It has been found that on heat treatment of PAN fibres for 3–4 h, dehydration reactions mainly take place; and on increasing the time from 3 to 9 h, mainly cyclization reactions take place. Intermolecular condensation reactions, which lead to the formation of polynuclear planar aromatic structures, take place after 11–12 h of heat treatment.3. A new approach has been proposed for interpreting DTA data, based on analysis of the components of the DTA curve equation, and also DTA parameters for control of the process of thermooxidative treatment of PAN fibres.4. It has been found by the XSA method that the cross-linking process leads to the formation of two-dimensional structures. An x-ray analysis figure has been proposed which makes it possible to discern the time intervals for occurrence of cross-linking.Translated from Khimicheskie Volokna, No. 5, pp. 8–11, September–October, 1993.     

Analysis of the operation of stretching stations in apparatus for the plasticized stretching of viscose tow

Conclusions Mathematical expressions have been obtained for calculating stretching forces for various schemes of stretching stations in apparatus for plasticized stretching.A qualitative comparative evaluation has been given for schemes of stretching stations in apparatus for plasticized stretching; it has shown a preference for a scheme with self-tightening rolls.Unreliability of the operation of stretching stations at low values of the coefficient of friction (0.01–0.05) has been demonstrated; this causes a need to search for ways to increase the coefficient of friction.Translated from Khimicheskie Volokna, No. 2, pp. 40–43, March–April, 1987.     

Effect of γ-radiation in the quality of high-molecular sulfite cellulose

Conclusions The effect of ionizing radiation on the molecular weight characteristics and ability to be dissolved of high-molecular, high-viscosity sulfite cellulose has been investigated.A radiation dose range of 5–10 kGy has been established, on absorption of which by high-molecular, high-viscosity sulfite cellulose, the degree of polymerization is reduced to 840. The reactivity is increased to 80/11 (% CS₂/% NaOH) and the share of the main fraction, having a DP of 200–800, rises to 52–60%. Irradiation of cellulose is suitable for use in the manufacture of viscose fibre.Translated from Khimicheskie Volokna, No. 1, pp. 30–31, January–February, 1988.     

V–Mg–O catalysts for oxidative dehydrogenation of alkylpyridines and alkylthiophenes

Vanadium appears to be the element that is most frequent (along with molybdenum) used in the catalyst formulations for oxidative dehydrogenation (ODH) of hydrocarbons and alcohols. In the present work the employment of ODH reaction in the presence of air has been extended for the preparation of vinyl substituted pyridines and thiophenes using vanadium (and for comparison molybdenum) oxide catalysts.The efficiency of vanadium–magnesium oxide catalysts in the production of vinylpyridines and vinylthiophenes has been evaluated. A strong dependence of the yield and selectivity of the latter upon the vanadium (molybdenum) oxide loading and the conditions of heat treatment were observed. In optimized reaction conditions V–Mg–O catalysts at the temperature approximate 450 °C ensured the formation of vinylpyridines and vinylthiophenes with the yield of 40–60% at the selectivity of 90%. In prolonged runs no visible changes in the performance of the catalyst were observed. DTA–DTG, XRD, IR ESR, NMR methods have been used detecting the formation of species of V–Mg–O catalysts that appear to be responsible for the catalyst efficiency in the reactions under consideration.     

Some features of the process of strengthening fibres from fluorine-containing polymers

Conclusions An anomaly in mechanical properties in spinning F2M fluorinated copolymer has been detected.The reason for preference for using a multistage scheme for strengthening fluoropolymers has been analyzed.Translated from Khimicheskie Volokna, No. 1, pp. 31–32, January–February, 1990.     

Photometric method of determining glucose content

Conclusions A photometric method has been developed for determining the glucose content of a working solution in the preparation of modified synthetic fibres.A replacement of the toxic arsenomolybdate reagent by phosphomolybdic acid has been carried out.Optimum conditions for determining glucose content have been selected. The time for analysis has been shortened.Translated from Khimicheskie Volokna, No. 1, pp. 57–58, January–February, 1987.     

Use of a domestic modifier in preparing high-modulus viscose fibre

Conclusions The possibility of using higher aliphatic amines of the C₁₇–C₂₀ fraction produced by domestic industry as a starting material for the synthesis of modifiers used in the manufacture of high-modulus viscose fibre has been investigated.The physicochemical and colloidal properties of the synthesized specimens have been determined. An optimum specimen has been selected, which was synthesized on the basis of synthetic aliphatic amines from the C₁₇–C₂₀ fraction containing a slight amount of C₂₁–C₂₅ homologs, for tests as a modifier under experimental unit conditions.A high-modulus viscose fibre has been prepared using the optimum specimen; in physicomechanical properties it is as good as fibre prepared using the imported Berol'-visko 314 modifier.Translated from Khimicheskie Volokna, No. 1, pp. 25–27, January–February, 1989.     

Preparation of poly-m-benzamide and fibres based on this compound

Conclusions 1. The authors have studied the principal laws of polycondensation of the hydrochloride of m-aminobenzoyl chloride. A polymer with a logarithmic viscosity of 0.7–0.9 has been obtained by the procedure developed.2. It has been established that poly-m-benzamide is an amorphous polymer with a glass-transition temperature of about 300°C. The weight loss of the polymer at 500°C is 2.5–3.5%.3. Fibre with a breaking length of 36 rkm (breaking length expressed in kilometers), high-heat resistance, and excellent thermal stability has been formed from solutions of the polymer.All-Union Scientific-Research Institute for Synthetic Fibres (VNIIV). Translated from Khimicheskie Volokna, No. 5, pp. 2–4, September–October, 1969.     

Air-permeability of fibrous materials prepared by aerodynamic spinning from polymer melts

Conclusions The procedure for determining the air-permeability of fibrous materials has been improved.The air-permeability of a wide assortment of nonwoven materials prepared by the aerodynamic spinning method has been characterized.Translated from Khimicheskie Volokna, No. 1, pp. 43–45, January–February, 1989.     

Colorimetric determination of formaldehyde content of cellulose film

Conclusions -- A selective and rapid colorimetric procedure has been developed for determining formaldehyde content in aqueous extracts of cellulose film.-- Metrological characteristics of the procedure in the formaldehyde concentration range 0.02–0.16 mg/liter have been found. The detection limit is 0.016 mg/liter of formaldehyde.Translated from Khimicheskie Volokna, No. 5, pp. 57–58, September–October, 1991.     

Structure of the superconductive (Bi−Pb)-4457 ceramic following explosive compaction

Metallographic and micro-x-ray-spectral analysis methods have been applied to explosive compacts of (Bi–Pb)-4457 to reveal their phase compositions. The presence of lead has been establshed in this case only for the Bi-2223 phase.Novosibirsk. Translated from Fizika Goreniya i Vzryva, No. 2, pp. 141–144, March–April, 1991.