Load-bearing elements made of high-strength,high-modulus fibres in an ionizing radiation field

The necessity of conducting research and obtaining experimental data on the effect of ionizing radiation on the physicomechanical properties of modern construction materials made of high-strength high-modulus fibres for predicting the reliability of performance and estimating the radiation lifetime of articles made of them was demonstrated.     

Calculation of the porosity of single- and multi-ply cloth made of chemical fibres

A system for automated calculation of the structure of multi-ply fabrics, SETKA, by qualitatively and quantitatively estimating the pore position parameters and shape of the channels in single- and multi-ply fabrics is examined. The SETKA system allows considering the characteristics of flow of gas or liquid through a fabric, increasing the reliability of calculations of its permeability. Translated from Khimicheskie Volokna, No. 5, pp. 52–55, September–October, 1998.     

High-strength,high-modulus fibres made from linear polymers: principles of fabrication,structure, properties,and use

The current types of ultrastrong and high-modulus fibres made from linear fibre-forming polymers — structure, principles of fabrication, properties, and basic areas of application — are examined. Most of the attention is focused on carbocyclic and heterocyclic para-aramid fibres, whose production capacities have reached 60,000 tons a year, the features of their structure and properties and areas of application. High-strength fibres made from other types of aromatic polymers (poly-p-phenylene benzobisoxazoles and thiazoles, polyarylates, polyvinyl alcohol, ultrahigh-molecular-weight polyethylene) are also briefly examined.     

Estimation of the through porosity of cloth made of chemical fibres in a blend with natural fibres and its correlation with air permeability

The accuracy and reliability of experimental data are determined by the choice of the method of determining the structural characteristics of materials to a significant degree. The data on the level of correlation and the type of functional dependence of the properties on the structure of materials obtained by correlation and regression analysis are a function of the reliability of the experimental data to a significant degree. Of the three methods of estimating the through porosity of materials examined here, the simplest and most widely used method of calculation provides the least reliable results. The most reliable data on through porosity can be obtained by the projection method of indirect estimation of the through porosity and it is recommended for practical research, especially when processing of materials with defined properties is the final goal.St. Petersburg State University of Design and Technology. Translated from Khimicheskie Volokna, No. 3, pp. 31–33, May–June, 1995.     

Basic stages in the development of high-strength and high-modulus viscose fibres

Translated from Khimicheskie Volokna, No. 2, pp. 17–19, March–April, 1991.     

Effect of defects in high-modulus viscose fibres on their physicomechanical properties

Conclusions -- As a result of microscopic investigation of high-modulus viscose fibres, it has been found that the various types of defectiveness in them amounts to 90%.-- Four characteristic groups of fibre defects have been determined: breakdown in morphological structure - 25%; gas-bubble content - 20%; mechanical contaminants from the viscose - 25%; and mechanical contaminants from the precipitation bath - 20%.-- It has been shown that the presence of defects in the fibre reduces its strength characteristics from 7.7 to 33%, depending on the form of defect and increases nonuniformity in these figures.Translated from Khimicheskie Volokna, No. 4, pp. 49–51, July–August, 1991.     

Statistical analysis of the scale factor in the strength of high-modulus fibres

Conclusions Distribution curves for the probability density of the strength values of complex SVM and Terlon yarns have been investigated with variation in the clamped length of specimens from 5 to 500 mm.The best conformity between the empirical distribution of yarn strength figures was observed for a distribution law for extreme values of the third kind, which conforms to the weak-unit theory.With increase in clamped length, disappearance of both very large and also of very small values of yarn strength takes place and because of this a shift in the modal value of strength takes place in the direction of low values. The latter circumstance is explained by the special features in the technology of making ultrahigh-modulus yarns.VNIIPV, Kiev Branch. Translated from Khimicheskie Volokna, No. 2, pp. 32–34, March–April, 1992.     

Use of cloth from synthetic fibres to clean up (filter) epoxy resins

Conclusions In the filtration of technological solutions of epoxy resins, one can use cloths based on polyamide, polyester, or polypropylene complex yarn, having 290–420 open (interfilament) pores per cm² and through porosity of 5–22%; these have a low hydraulic resistance and permit one to attain the best filtrate quality. They can successfully replace the types of cloths from natural fibres which are being used at present.It is advisable to carry out laboratory evaluation of the suitability of cloths for filtering epoxy resin solutions from the figures for their shrinkage and loss of strength under the action of the solution being filtered; these should not exceed 5–7 and 15–20%, respectively.Translated from Khimicheskie Volokna, No. 4, pp. 48–49, July–August, 1987.     

Spinning of oxide fibres made of natural cellulose materials

The possibility of obtaining high-melting fibre materials from plant fibres and textile production wastes containing 40–60 wt. % cellulose was demonstrated. The optimum conditions of preliminary chemical treatment of natural raw material to increase the sorption capacity of the materials were determined. The conditions of heat treatment of salt-containing natural fibre materials which would allow regulating the crystal and pore structure of oxide fibres were established. Translated from Khimicheskie Volokna, No. 5, pp. 27–31, September–October, 1997.     

Performance characteristics of heater elements made of carbon fibres

The optimum concentration of a solution of adhesive required for impregnating CF is 35±5%, which corresponds to a 45±5% content in the fibre. An electric current is transmitted in CF due to the relatively low resistance of the fibre filaments and according to a “chain” scheme. The change in the strength of CF under the effect of cyclic double bending and preliminary loading was determined. The characteristics of the increase in the electrical resistance as a function of the number of double bending cycles, correlated with breaking of the CF filaments and a decrease in the contacts between them, were established. __________ Translated from Khimicheskie Volokna, No. 3, pp. 33–35, May–June, 2006.     

Energy loss partitioning during ballistic impact of polymer composites

The objective of this study is to determine the energy dissipation processes in polymer-matrix composites during impact of ballistic projectiles. These processes include heat, fiber deformation and breakage, matrix deformation and fracture, and interfacial delamination. In this study, experimental measurements were made, using specialized specimen designs and test methods, to isolate the energy consumed by each of these processes during impact in the ballistic range. Using these experiments, relationships between material parameters and energy dissipation were examined. Composites with the same matrix but reinforced with Kevlar, PE, and graphite fabric were included in this study. These fibers were selected based on the differences in their intrinsic properties. Matrix cracking was found to be one of the most important energy absorption mechanisms during impact, especially in ductile samples such as Spectra-900 PE and Kevlar-49 reinforced polymer. On the contrary, delamination dominated the energy dissipation in brittle composites such as graphite reinforced materials. The contribution from frictional forces also investigated and the energy partitioning among the different processes evaluated.