Том 49, № 1 (2017)

Known data are generalized on the structural transitions and orientational strengthening of yarns made from different polymers, from the standpoint of the current state of the art. Their characteristic features as well as the similarities and differences for processes forming the structural and mechanical properties are demonstrated. Consideration of the process of orientational drawing of PET is emphasized, letting us show the characteristic features of structural transitions from the amorphous to the crystalline state. Material in this paper has combined basic scientific data on problems of orientational strengthening, which is quite important in the current stage of development of polymer technology for designing new processes.

The influence of the spinneret draw ratio and subsequent solid-state stretching of polypropylene multifilament yarns (PMY) on changes in the orientation of crystallites and molecular chains in the polymer amorphous regions was studied using x-ray structure analysis. It was shown that crystallites and molecular chains of amorphous polypropylene (PP) became significantly more oriented already for a yarn spinneret draw ratio of 2400% and changed little if it was increased further. Additional solid-state stretching of yarns at elevated temperature had practically no effect on the orientation of PP crystallites but did halve the misorientation angle of molecular chains in the polymer amorphous regions. This phenomenon suggested that the substantial decrease of the elongation at break and increase of PMY physicomechanical parameters could be attributed to distribution of the applied load onto a larger number of continuous chains.

Experimental data on molding of three-layered paperboard testliner from secondary fibre with an aerodynamically formed middle layer are presented. The layer-wise optimum ratios of low-quality fibres in the three-layered testliner with an aerodynamically formed middle layer for reducing paperboard production cost are given. The experimental data show the advantage of introduction of aerodynamic molding technology.

A regression equation that takes account of the dependence of imbalance of yarns with a 100 tex linear density on the first and second twist into two and then five strands, respectively, was derived by full factorial experiment. The optimum twists were obtained by evolutionary planning.

We have developed a temperature-regulating textile material in which the electrically conductive element is carbon yarn, while the electrically insulating element is cotton fabric No. 210 and the fusible interlining material Flizelin G 405. We have established the characteristics of structure formation in the temperature-regulating material, providing light weight, softness, strength, vapor permeability, reliable binding of the structure, and the possibility of application in clothing manufacture.

The technique of experimental investigation of moisture diffusion coefficients in fabrics is described, the results obtained are shown to depend on the relative humidity of air, the values of diffusion coefficients for vapor permeability and sorption are compared, and the physical laws of the moisture transfer process are analyzed.

The piercing resistance of ballistic fabrics was studied as a function of both the resin concentration in EtOH solutions and the number of fabric layers.

An algorithm is proposed for modeling emergence and development of defects in one-dimensional articles from polymeric material under stationary performance conditions. Computer simulation of probabilistic processes was used for the modeling. The mechanisms and changes in the process under stationary conditions of impact on the material were studied.

The problem of increasing the adsorptive and adhesive interaction at the phase boundary between a matrix and a reinforcing fibrous filler in the creation and application of carbon-filled plastics was investigated. A promising way of achieving this aim is to develop methods for surface treatment of the carbon reinforcing fillers and, particularly, to modify the surface of the carbon fibrous materials by plasma treatment.

The dependence of electromagnetic radiation reflection coefficient of nonwovens on the content in them of carbon fibres cut to various lengths is studied. A technique for inserting electroconductive carbon fibres, which ensures formation of an intermediate layer of these fibres between fabrics from dielectric fibres, is described. The frequency dependence of the reflection coefficient on the intermediate layer composition and carbon fibre cut length for fabrics and multilayered materials obtained by joining fabrics is determined. It is shown that the multilayered materials are of interferential-absorptive type, but are also capable of absorbing low-frequency electromagnetic radiation.

Methods for the synthesis of copper nanoparticles by reduction of copper sulfate in an aqueous medium in the presence of polyvinylpyrrolidone are examined. The effect of the content of the employed reagents, the pH of the medium, and the temperature on the synthesis of copper nanoparticles was investigated. The antibacterial characteristics of cellulose materials modified with copper nanoparticles are described.

Methods of mathematical modeling of processes of relaxation and creep of polymer filaments on the basis of a spectral interpretation of the processes are described. It is shown that the analytic forms of the relaxation and delay (creep) spectra are completely determined by the mean-statistical values of the relaxation and delay times as well as by the structural coefficients of these processes, which basically characterize the intensity of relaxation and creep processes.