Vol 48, No 1 (2016)

This paper analyzes the characteristic features of necking during drawing and ultrahigh-speed spinning of polyethylene terephthalate (PET) yarns. It is established that despite the formal analogy, there are significant differences between necking in the indicated processes, due to the non-isothermal nature of ultrahigh-speed spinning. Based on literature data and my own ideas, I propose my own version of the necking mechanism during ultrahigh-speed spinning, which adds to information known about this process. When a neck appears during the ultrahigh-speed spinning process, the determining factors may be those related to the abrupt change in viscoelastic properties under the influence of high strain rates and the balance of acting forces.

The smoothing capability of extrusion equipment was evaluated using the accumulated shear strain. The effects of the polymer rheological properties and its processing conditions on the amount of accumulated strain were analyzed using a regression equation obtained from a numerical model of heat- and mass-transfer processes in the extruder channel.

The principal possibility of using oxy-PAN waste of different oxidation states as the reinforcing systems in polymerization filling of PA-6 is shown here. It is proven that PA-6 modified at the synthesis stage with 10% oxy-PAN waste is characterized by the tendency to enhance the physical and mechanical properties. Its higher workability ensures the formation of monolithic material with the minimal number of defects.

The optimum modification parameters for cellulose-hydrate fibers finished with solutions of AGM-9 and Duron OS 3151 preparations were determined. The properties of the modified cellulose-hydrate fibers were studied. The adhesive properties of the modified fibers were evaluated. It was found that modification helped to increase the strength and adhesive characteristics of the fibrous filler, which could be recommended for preparing an epoxide composite.

Theoretical calculations are performed for three compositions of Kamvol worsted yarn with inlay of polyacrylonitrile (PAN) fibers. Analytical method of designing yarn from multicomponent blend under conditions of a marked difference in geometrical and strength properties of the fibres is used for the calculation.

We have studied the performance of different methods for processing needlepunched material made from blends of polyester, bicomponent, and polypropylene fibers. The performance of needlepunching and various processing methods depends on the choice of parameters for evaluating the mechanical properties of the materials. A correlation has been found between different parameters used to evaluate the deformation-related and strength-related properties of the original needlepunched materials. However, there is no such correlation for the processed materials.

An algorithm is proposed for analyzing non-stationary time series obtained by monitoring technological processes or properties of the developed unidimensional fibre products (yarn, sliver, roving, tow, complex yarn, etc.). The algorithm is based on the correlation, known from the theory of chaos dynamics, between the trend and the random variations of values and consists in simultaneous evaluation of the trend of average and a range of variations. It can be used to identify and predict the type of nonstationary state in terms of the mean level and variations. The information gathered with its aid will make it possible to predict possible structural changes (bifurcation) in the characteristic features of the trends of time series. The algorithm can be used in many areas of analysis, control, and prediction of technological and technoeconomic processes.

In light of the current economic situation, the final stage in the production of textile fabrics needs to be carried out in a more efficient manner. This can be done by automating product inspection, packaging, and the batching of products for shipment to customers and by combining these operations into a single SCADA system. The final stage in fabrics production is analyzed, plans are proposed for partially or completely automating it, and a probability-based approach is described for evaluating performance during the last stage.

We propose a theory for the kinetics and final transformations in two types of self-similar processes, when the operators describing the process at each instant of time are inversely or directly proportional to the difference between the parameters corresponding to the final state and the state achieved. In the first case, the parameter governing the stability of the system reaches a critical value, and the final stage occurs in avalanche fashion. In the second case, there is no critical state, the final stage occurs asymptotically, and the final state is an equilibrium state. As the model processes, we take the fracture process in the composites and their strengthening process. The critical parameter in the fracture process is a measure of the stress tensor. For this process, we obtain an equation relating the initial and final degree of damage in the composite and the operator generating the self-similar process; we construct the theoretical time-to-fracture distribution functions vs. the applied stress, including zero fracture probability. The distribution functions can be constructed without long-term testing. We have obtained an equation describing the kinetics of the strengthening process and an expression defining the equilibrium state. The theory has been confirmed by experiment. The maximum testing time was ~20000 h.

The deformational properties of Aramid fibers are subjected to a comparative analysis. It is shown that dividing processes involving the deformation of Aramid textiles into an elastic component and a viscoelastic-plastic component allows the proper choices to be made among materials which have certain elastic-mechanical properties. Comparative analysis of the viscoelastic characteristics of Aramid fibers is the foundation for solving the engineering problems encountered in the design and selection of materials having specified elastic and viscoelastic-plastic properties.

This article examines aspects of analyzing and estimating the systematic error in measuring the tension of alumina fibers on a tension tester with stationary fiber guides. The measurements are made during the rewinding and twisting of the fibers on an experimental stand. Calculations are performed to determine the components of the systematic error for the given testers. Among these components are the constant error and the periodic error, which in turn depend on the conditions of motion of the fibers in the tester’s guides, the fibers’ geometric characteristics, and the changes in the friction coefficient in relation to fiber velocity.

The processes which take place during the winding of hollow fibers are analyzed. The article describes a unit that has been developed to receive flows of hollow fibers of polysulfone (for example) created on equipment designed for forming, finishing, and drying. A bundle is formed by a certain number of hollow fibers having a certain length. As a hollow fiber is wound on the reel of the unit, it is subjected to tensile, centrifugal, and bending forces and the external pressure exerted by other fibers. The method that is described for calculating the stresses which develop in hollow fibers during their winding onto a reel makes it possible to determine the diameter of the reel’s working spokes that is optimum from the standpoint of keeping the stresses at an acceptable level.

In 2014, the global output of all types of textile fibres was 93.7 million tons, which was higher by 4.1% than in 2013, including synthetic by 3.1%, hydrated cellulose by 0.3%, and natural by2.5%. The chemical fibre output was 63.2 million tons, where polyester (PE) dominated with a 74% share. Among the chemical fibre manufacturing countries, China occupied the overwhelmingly dominant place with 68% of the global output. The share of this country in the PE fibre domain was 71% of capacity, 69% of output, 65% of consumption, and 36% of export (of which 53% was technical yarns) globally. The scales of manufacture of other types of chemical fibres were much smaller in 2014 (global share, %): hydrated cellulose 10, polyamide (PA) 8, polypropylene (PP) 5, and polyacrylonitrile (PAN) 2. Currently, PP fibres play the leading role in nonwoven raw materials market.