Vol 47, No 5 (2016)

Treatment of polyethylene terephthalate (PET) bottle wastes is one of the ways of utilizing solid household garbage accumulated in dumps worldwide, including in Russia. A large part of the utilized PET bottles in the form of washed flakes is processed into staple fibre for nonwoven materials and fillers. The German company BBE offered equipment and technology that allow conversion of PET flakes into a product akin to a standard primary polymer, which makes it possible to cast polyester textile filaments of the desired quality and thereby not only to expand the sales market, but also to solve important ecological and economic problems.

Wetting of carbon fibers by model liquids (water and octane) and melts of pure coal-tar pitch and that with myristic acid added as a surfactant was studied by the Wilhelmy method. It was shown that the contact angles of the carbon fibers by the pitch that were calculated using wetting data for the model liquids agreed with the directly measured values. Addition of myristic acid equalized the polar and dispersive components of the pitch-melt surface free energy and improved the wettability.

Results of the analysis of the influence of hydrogen bonds in aromatic polyamides on technological processing methods for the production of heavy-duty aramid yarns CVM, Rusar, and Ruslan are presented herein. Quantum-chemical calculations of model fragments in conjunction with vibrational spectra in the infrared range have shown that, depending on the hydrogen bonds between the benzimidazole groups, “self-orientation” processes emerge caused by the increase in energy of the hydrogen bonds in the aramid yarns and fibers. This explains the uniquely high values describing mechanical properties of the yarns and their performance characteristics in cloths, plastics, and spool products.

We consider the influence of wind load on the electrophysical properties of carbon fibers used in systems for machine and structural diagnostics.

The synthesis of nanoparticles of bismuth was performed, which consisted of chemical reduction from Bi(NO₃)₃ solution. Optimal parameters for the reduction of bismuth to zero valence metal state, and its application to the fabric were developed. The modified fabric subjected to microwave radiation yields a decrease in the radiation dose. The material can be used in radioprotective clothing with enhanced partial protection, which includes overalls, helmet, gloves, and shoe covers made from radio-reflective materials.

An analysis is made of effective models that have been proposed for predicting the air permeability of needle-punched nonwovens in accordance with the requirements of the Russian standard. An approach that entails constructing models with a single structural parameter is suggested. The parameter can be thickness, surface density, volumetric density, or the space factor. The given approach precludes obtaining models with one correction factor. Models constructed with two correction factors make it possible to predict air permeability for certain values of the structural parameters. The optimum model uses surface density as the structural parameter.

Supramolecular structure formation of poly(3-hydroxybutyrate) ultrathin fibers prepared by electrospinning and the influence of low concentrations of silicon and TiO₂ nanoparticles on the structure, physicomechanical and sorption properties, and resistance to thermal destruction and thermoand photo-oxidative destruction of non-woven fibrous material based on these fibers were studied. It was found that nanoparticles promoted the formation of thinner fibers with enhanced physicomechanical parameters and a structure that was more resistant to thermal and thermo- and photo-oxidative destruction and had a positive effect on the growth dynamics of mesenchymal stem cells.

The production and properties of polypropylene threads modified by small amounts of iron-containing nanoparticles were studied. The nanoparticles were stabilized during the synthesis by immobilizing them in a low-density polyethylene matrix. The structure of the modified threads was examined. The strength, friction coefficients, surface electrical resistance, and antimicrobial properties of the threads were evaluated.

We evaluate the industrial processability of high-strength and high-modulus multifilament yarns in weaving. The procedure for evaluating the processability of a yarn is based on determining the abrasion resistance of the yarns under conditions simulating loom operation. We determine the basic physical and mechanical properties of different types of multifilament yarns, including their abrasion resistance, which affect the processability of the yarns in weaving, letting us predict the weaving conditions.

A classification is presented for well-known methods and equipment used to evaluate the composition and uniformity of blends of natural and chemical fibers. A visual method, a photometric method, and a method based on differences between the physicochemical properties of the components being blended are analyzed. Aspects of the use of these methods are also discussed.

Scientific research and experimental-design work are performed to improve the effectiveness of regenerating bag and cassette filters by reverse pulse scavenging. It is recommended that the velocity and flow rate of the compressed air used for scavenging be chosen as the regime parameters, depending on the physico-mechanical properties of the dust that is being captured. A method of calculating the grouped distribution of collectors is proposed to uniformly distribute the compressed air among the scavenging nozzles. It is also recommended that swirl nozzles be used to equalize the pressure pulses along the filter elements.

To study the dynamics of a control object, it is necessary to obtain its transfer function or construct a model of it. The process of identification was carried out by Simoyu’s method and by means of the program Ident, which is built into the system Matlab. The input and output variables of the object were observed by performing an active experiment. A stepped control action was applied and a recording was made of the resulting output data, which was in the form of a transient response. To eliminate experimental errors, the tabulated data was smoothed with the use of a cubic spline after normalization. Double smoothing was performed with a step of 0.04 sec and then a step of 0.02 sec to record the volume of data.