Structural features and strength of carbon fibres

Conclusions -- Dimensions, orientation of the ordered regions, and also the heterogeneous structure parameters have been determined for a number of foreign and domestic high-strength and high-modulus carbon fibres (CF). Characteristic features of the behavior of the heterogeneous structure of CF with change in dimensions of the ordered regions have been noted.-- It has been shown that small dimensions of the ordered and unordered regions are characteristic of high-strength CF together with an increased mean density of the unordered and porous phases.-- An attempt has been made to establish correlations between the ultimate strength of CF in extension and the heterogeneous structure parameters of the fibre.Translated from Khimicheskie Volokna, No. 1, pp. 47–49, January–February, 1991.     

Some features of spinning hollow fibres from polycarbonatesiloxane melts

Conclusions The following parameters have been determined as a result of calculations: fibre tension, solidification path length, and the change along the spinning path of the following: stretching stresses, speed, radius, wall thickness, and fibre temperature.It has been shown that, with increase in take-up speed, the length of the section of fibre deformation is reduced, varying practically proportionally to the flow rate of the polymer system.Stability of the process of spinning hollow fibres from polycarbonatesiloxane melts is assured within a narrow range of stretching force.Translated from Khimicheskie Volokna, No. 3, pp. 41–43, May–June, 1989.     

Anion exchange activity of electrochemically bonded ethylene diamine on carbon fibres

Carbon fibre based anion exchangers were prepared through electrochemical oxidation and bonding of ethylene diamine on fibre electrodes in acetonitrile and subsequent formation of the chloride salts of the ammonium groups.Catalytically active noble metals can be introduced into the carbon matrix after ion-exchange with complex salts, carrying the noble metal in their anionic component, and subsequent cathodic reduction of the noble metal ions to the metallic state, in aqueous solutions.The free amino groups of the carbon fibres modified with oxidized ethylene diamine can be used for the preparation of chemically modified electrodes via an amidization reaction with acid chlorides.The amount of the oxidized ethylene diamine attached to the carbon fibre surface exceeds a monolayer coverage, suggesting the formation of chain and bridge configurations on the carbon fibres. Investigation was performed by cyclic voltammetric, chrono-amperometric, potentiometric and impedance measurements. The order of magnitude of the anion-exchange capacity of the produced material for small anions was 1 meq per g carbon fibre.     

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.     

Some features of production of silver-containing carbon materials

Carbon sorbents with different specific surface areas were selected for studying sorption of precious metals from metal-containing solutions. It was found that the maximum amount of sorbed silver is a function of the specific surface area of the carbon sorbent. The maximum sorption capacity decreases in the order ACF > AC > TEG. The features of the morphology of metal-containing carbon materials were revealed as a function of their properties, the nature of the metal, and the sorption conditions.     

Effect of surface-treatment and moisture on realization of the strength of carbon fibres in microplates

Conclusions The coefficient of strength utilization of CF in microplates can be brought to a level which is characteristic of glass fibres.Humidifying of CF, with filling of defects of transitional and macroscopic size, reduces the coefficient of CF strength utilization.Chemical or heat-treatment of CF does not guarantee a high coefficient of strength realization if, during the course of spinning, adsorption of moisture by the fibres takes place with filling of the defects having a transition size.Published to stimulate discussion.Progress MP, Samarskii Polytechnic institute, Perm'. Translated from Khimicheskie Volokna, No. 2, pp. 30–32, March–April, 1992.     

Some features of spinning cuprammonium fibres into precipitation baths containing calcium salts

Conclusions On the basis of data on precipitating power and the rate of dehydration of cuprammonium solutions of cellulose, the fundamental possibility has been demonstrated of spinning fibres from such solutions into precipitation baths containing calcium salts, using the technological scheme for viscose fibre manufacture.The dependence of the basic characteristics of the freshly-spun fibre on calcium salt content and temperature of the precipitation bath has been found.Moscow Textile Institute. Translated from Khimicheskie Volokna, No. 1, pp. 11–13, January–February, 1987.     

Some special features in preparing hydrocellulose fibres and yarns from concentrated viscoses

Conclusions The possibility has been demonstrated of preparing hydrocellulose fibres and yarns with good strength and elastic properties from concentrated viscoses at an -cellulose content of 12% with a DP of 250 and an NaOH/-cellulose ratio of 0.68.Translated from Khimicheskie Volokna, No. 2, pp. 25–26, March–April, 1990.     

Some features in the lubrication and brightening treatment of polyester fibres and yarns

Translated from Khimicheskie Volokna, No. 6, pp. 44–48, November–December, 1991.     

Structure of carbon fibres

Conclusions -- Carbon fibres have been examined as carbon band oriented amorphous-crystalline polymers.-- Characteristic regions in the formation of the structure of carbon fibres have been established, plus the interconnection between structural parameters.-- The components of preferential orientation of carbon fibres have been marked out, and a systematization of orientation in the transverse section of fibres has been presented.-- The character of change in axial component of texture with change in treatment temperature has been given, plus the connection between it and the elasticity and strength of fibres.-- A characteristic has been proposed for evaluating the activity of the surface of carbon fibres.Combustible Minerals Institute. Translated from Khimicheskie Volokna, No. 3, pp. 26–29, May–June, 1991.     

Kinetics of sorption-desorption of moisture by chemical and natural fibres and yarns

The kinetics of sorption and desorption of moisture by chemical and natural fibres were investigated. A mathematical approximation of the kinetics of sorption and desorption with exponential dependences whose coefficients characterize the rate of absorption and discharge of moisture is reported. The coefficients of internal mass transfer of moisture for different types of fibres were calculated. The hygroscopic characteristics of fibre materials in production, processing, and use can be predicted and compared for different types of fibres and blends with these dependences.St. Petersburg State University of Design and Technology. Translated from Khimicheskie Volokna, No. 4, pp. 23–26, July–August, 1995.     

Some features of chemical structure of the surface of fibres based on aromatic polyamides

Conclusions Under any heat treatment of fibres based on aromatic polyamides, the composition of their surface differs considerably from the stoichiometric. The presence of silicon-containing compounds, in our opinion, is a consequence of the technological fibre preparation processes.The discovered features of the chemical structure of fibres are apparently able to exert an important effect both on the physico-mechanical characteristics of the fibres themselves, and also on the processes of formation and degradation of an adhesive fibre-matrix bond in polymeric composites.Translated from Khimicheskie Volokona, No. 1, pp. 8–9, January–February, 1989.     

Some features of the flow of a polypropylene melt in the formation of fibres

Conclusions 1. On passing through a spinneret orifice, a polypropylene melt behaves as a structured pseudoplastic liquid and its properties are described by flow laws analogous to the flow laws in a capillary viscometer.2. The dependence of the effective viscosity of a polypropylene melt on its molecular weight, temperature, and shear stress has been established in the form of a semiempirical equation.3. The effective viscosities of a polypropylene melt on flow through spinneret orifices in the formation of a fibre have been determined. It has been shown that a change in the effective viscosity does not affect the properties of the fibre.(VNIIV) All-Union Scientific Research Institute for Synthetic Fibres. Translated from Khimicheskie Volokna, No. 2, pp. 14–16, March–April, 1969.     

The stabilisation of carbon fibres studied by micro-thermal analysis

Micro-thermal analysis, or local thermal analysis, is a relatively new technique that combines the imaging capabilities of atomic force microscopy with the physical characterisation capabilities of thermal analysis. This paper reports the application of this technique in a study of the stabilisation process of pitch-based carbon fibres. The technique allowed the determination of softening temperature profiles across model large diameter fibres, as a function of the stabilisation degree. The changes in the softening temperatures promoted by the stabilisation were related to the local oxygen content of the fibre measured by electron probe micro-analysis (EPMA). The depth of the stabilised region was also determined. The results obtained indicate that the higher temperatures studied (180-200 °C) promoted a rapid oxidation of the outer region of the fibre, which acts as a surface diffusion barrier for oxygen, longer times being required for full-stabilisation of the fibres.     

Activation of carbon fibres from pitch by atmospheric oxygen

Oxidative etching of carbon fibres obeys the principles of polychromatic kinetics of polymer reactions. The differences in the efficiency of activation of carbon fibres based on different raw materials by thermooxidation in air are due to the morphological features of their structure. The possibility of obtaining activated carbon fibres by oxidation of the starting carbon fibres from isotropic pitch with atmospheric oxygen at high temperature was demonstrated.Translated from Khimicheskie Volokna, No. 6, pp. 40–43, November–December, 1994.     

High-strength high-modulus carbon fibres

Translated from Khimicheskie Volokna, No. 3, pp. 5–8, May–June, 1991.     

Fabrication of carbon fibres from wet-spun commercial polyacrylonitrile fibres

The possibility of fabricating carbon fibre from commercial PAN fibres for textile applications was demonstrated. It is necessary to make some changes in the temperature—time conditions for total completion of the thermal stabilization process. Better strength of the carbon fibres, equal to 1401 MPa, was attained in conducting thermal stabilization cycle B. __________ Translated from Khimicheskie Volokna, No. 5, pp. 31–33, September–October, 2006.     

Microstructure of activated carbon fibres

Conclusions Quantitative data have been obtained on the elements of ACF microstructure and its genesis during the process of carbon fibre oxidation.The use of model concepts has made it possible to considerably expand the informativeness of the adsorption method of investigating ACF microstructure.The anisotropic ordered structure of carbon fibres makes it possible to synthesize adsorbents having a micro- or micro- and mesoporous structure with practically complete absence of macropores.On the basis of graphic dependences obtained, it is possible to predict the preparation of ACF with assigned properties.Translated from Khimicheskie Volokna, No. 6, pp. 14–16, November–December, 1987.