Key Engineering Materials Vol. 869

Abstract: In the present paper we study the effect of complexation in linear negatively charged polyelectrolytes with different alkali ions. With combination of IR-spectroscopy, X-ray diffraction and nanocalorimetry, we attempted to explain unusual solubility, crystallinity and thermal stability of these polymers. The increase of thermal stability and insolubility in water in series of semi-crystalline polysalts as K⁺ ≤ H⁺ <Na⁺ was explained by effectiveness of formation of chelating complex. Insoluble in water sodium salt shows the highest thermal stability of crystal phase up to . In contrast, well soluble in water amorphous lithium salt does not self-organize in chelating complex and is presented in ionic form.

Abstract: The polymer composites based on low-density polyethylene (LDPE), ethylene vinyl acetate copolymer (EVA) and fly ash (FA) without and with vinyltrimetoxysilan (VTMS) modification were prepared by melt mixing in a Haake Rheomixer. The FT-IR spectra indicated the bonds between LDPE/EVA and FA modified by vinyltrimetoxysilan were dipole - dipole interaction and hydrogen bonding. Thermal oxidation stability of the LDPE/EVA/VFA composites are higher than those of the LDPE/EVA/FA composites. Thermal oxidation stability of the LDPE/EVA/VFA composites and the LDPE/EVA/FA composites were higher than the LDPE/EVA blends. Putting fly ash into polymers, thermal oxidation stability of composites increased and significantly increased when using modified fly ash (MFA).

Abstract: The fly ash from Pha Lai power plant was modified by vinyltrimetoxysilan (VTMS). The polymer composites based on low-density polyethylene (LDPE), ethylene vinyl acetate copolymer (EVA) and fly ash (FA) without and with vinyltrimetoxysilan (VTMS) modification were prepared by melt mixing in a Haake Rheomixer. The tensile strength and elongation at break of the LDPE/EVA/VFA composites were also higher than those of the LDPE/EVA/FA composites. The FESEM images proved that FA-VTMS particles disperse more regularly in the polymer matrix in comparison with FA without VTMS modification. In addition, the surface modification of the FA reduced the size of agglomeration of FA particles.

Abstract: The paper presents the results of studies of the reaction of the interaction of phenol with cyclohexene (CH) in the presence of a Zeolite-Y catalyst impregnated with phosphoric acid and studying the dependence on the yield and selectivity of the target product on various parameters. As a result of the study of the phenol cycloalkylation by cyclohexene, optimal conditions were found, the yield of which is 81.6 % of theory for the taken CH, and the selectivity is 94.0 % for the target product. The developed mathematical model of the processes of the interaction of phenol with cyclohexene in the form of a regression polynomial made it possible to find the optimal values ​​of the input variables.

Abstract: The current state of the cosmetology industry in the field of eyelash extension services is analyzed. It is concluded that the popularity of this type of service, despite the negative impact on eye health, will grow in the near future. The main symptoms that occur when using this procedure are analyzed. Among the most common symptoms should be noted a feeling of heaviness of the eyelids, burning, discomfort associated with a decrease in the field of view. It is noted that despite a number of works in this area to date, there is insufficient research, both from the point of view of the analysis of clinical cases, and from the point of view of developing safer adhesive compositions. An analysis is made of the characteristics of adhesives used in domestic cosmetology rooms. At the same time, attention was paid to the following: country of production, composition, texture and texture, setting speed, wearing time, shelf life, recommended temperature and humidity level. A typical composition of glue for eyelash extension contains the following components: cyanoacrylate and its derivatives (± 90 %); polymethylmethacrylate (PMMA) (± 6 %); black pigment - carbon black (± 4 %).

Abstract: Polymer-based sealing materials currently play a large and important role in almost all areas of industry. The use of sealants can increase the energy saving of building structures, the safety of vehicles, etc. Sealants are equally used in such specialized applications as the aerospace field, and are also used to solve everyday problems, such as sealing plumbing. The main consumption of sealants is in construction and automotive. This review provides data on the global and domestic market for sealing materials; The basic terms and definitions used in the field of adhesive and sealing materials are analyzed. The main differences between the terms adhesive and sealant are discussed. The classification of sealants is given in accordance with modern international regulatory documents. It is disassembled that they are one-component reactive hot-melt sealants. Their main advantages and disadvantages are listed. It is noted that the development of the industry of sealing materials is likely to move towards the development of moisture-curing compositions based on silane-modified polymers. This assumption is supported by a fairly detailed classification of silane-modified polymers in the FEICA classification guide for sealants and adhesives.

Abstract: The production of nonwovens over the past few years remains one of the most promising areas in the textile industry. This is due to the short cycle of production of such materials from raw materials to finished products and the ability to produce at a low cost a wide range of materials for both household and technical use. In particular, non-woven materials are widely used for the manufacture of disposable medical clothing and underwear. An important characteristic for surgical clothing is an indicator of bursting strength. This study simulates material deformation similar to elbow pressure when bending the arms or knee when bending the legs. Since the lower part of the sleeve of the product refers to the critical zone of the product, i.e. to the zone most likely to be involved in the transfer of infectious pathogens to or from the wound, the sterile product must have a significant margin of bursting strength. The effect of the absorbed dose of electronic radiation on the strength during the bursting strength of nonwoven medical material of SMS design with a surface density of 35 and 50 g/m² obtained using the spanmelt technology was studied. It is shown that electronic radiation significantly reduces the resistance of the nonwoven to bursting strength. With an absorbed dose of 40 kGy, the material no longer meets the requirements for surgical clothing and linen by regulatory documents. For non-woven materials obtained using spanmelt technology, the bursting strength rate is even more sensitive to the action of ionizing radiation than the tensile tensile load, therefore, this indicator is recommended to be used as a characteristic indicator of radiation resistance.

Abstract: The authors have studied the impact of mechanomagnetic activation (MMA) of the solutions NA-CMC, widely used for mixing water-cement paste, on the structure and properties of cement composites. By the method of dynamic light scattering, the appearance of nanosize particles of grouting fluid’s dispersion phase has been proved. On the base of the results of X-ray diffraction analysis, there have been found alterations of cement stone structure; the influence of MMA on the processes of structure formation has been proved; the principal components of cement stone structure have been identified.

Abstract: The synthesis and properties of wholly aromatic polyesters are of considerable practical importance to create functional and high-performance materials. In the present study, by means of catalytic polyesterification using titanium (IV) butoxide, we’ve synthesized wholly aromatic oligomers derived from 4-hydroxybenzoic acid (HBA), aromatic diacids and dibasic phenols. As revealed by FTIR measurements, the average molecular weight of oligomers has varied from 500 to 1400. The results of DSC have shown endotherm peaks attributed to a phase transition of low-molecular oligomers from crystalline state to mesophase and further isotropization. The synthesized oligomers were resistant to high temperatures up to about 300-320 °C.

Abstract: Metal-containing monomers based on maleates of copper and zinc, cinnamate of copper and acrylate of zinc with 4-phenyl-2,2′:6′,2′′-terpyridine ligand were prepared for the first time and characterized using a number of analytical techniques including infrared spectroscopy, elemental analysis and thermal gravimetric analysis. According to the results of the thermal analysis, the coordination mixed-ligand complexes based on zinc salts are more stable than copper one both in the case of monocarboxylic acids and dicarboxylic acids. The first stage of polymerization according to results of mass spectra of gaseous products is initiated in accordance with the Borodin–Hunsdiecker mechanism: the initial decarboxylation leads to the formation of carboxy biradicals, which, in turn, cause the polymerization and the formation of polymers. In this paper we also describe facile two-step Kröhnke-type synthesis of 4′-phenyl-2,2′:6′,2′′-terpyridine from 2-acetylpyridine and its NMR spectrum.