Key Engineering Materials Vol. 899

Abstract: Based on magnesium carbonate and antimony oxide (V), MgO•Sb₂O₅ was obtained. In the formulation of fire-resistant cable PVC-plasticate, antimony (III) oxide was replaced by MgO•Sb₂O₅ and the fire resistance and physical and mechanical properties of the resulting compound were investigated. It is shown that the replacement of antimony (III) oxide in the composition of PVC cable compound MgO•Sb₂O₅ leads to the production of a compound that is not inferior in its characteristics to the original plastic compound. In particular, the fire resistance of cable PVC-plasticate, standard industrial formulation and with the obtained MgO•Sb₂O₅, is practically the same (OI=32%). It has been established that the physical and mechanical characteristics of the cable compound, when replacing antimony oxide (III) with MgO•Sb₂O₅ in the formulation, remain at the level of the original compound, while MgO×Sb₂O₅ will have a less negative impact on the environment.

Abstract: New polyconjugated polymers have been synthesized by oxidative polymerization of benzylidene-m-phenylenediamines. The morphology, particle size distribution, thermal and electrical properties of the obtained polybenzylidene-m-phenylenediamines have been investigated. The morphology of the particles of the obtained polymers was determined. It was shown that the synthesized polybenzylidene-m-phenylenediamines exhibit noticeable thermal stability and electrical conductivity. In this case, the thermal stability and the process of decomposition of polybenzylidene-m-phenylenediamines substantially depend on the chemical structure of the side fragments of macromolecules.

Abstract: Aliphatic linear oligoesters with terminal hydroxyl groups and given molecular weight characteristics, hydroxyl and acid numbers were synthesized by esterification of adipic acid, ethylene glycol and butanediol-1,4. It was found that the main properties of complex oligoesters largely depend on the ratio of the starting reagents. The kinetic regularities of the process of esterification of adipic acid, ethylene glycol and butanediol-1,4 have been studied and determined. It was found that the duration of the vacuum stage of esterification in the presence of organomodified montmorillonite is noticeably shorter than when using a commercial catalyst.

Abstract: The influence of various concentrations of the selected phosphorus-containing stabilizers on the properties of stabilized and unstabilized polyetheretherketone has been investigated by the methods of spectroscopic, thermal and physical-mechanical analysis. The most effective stabilizer was determined, the positive effect of certain concentrations of phosphorus-containing stabilizers on the thermal stability of polyetheretherketone was revealed.

Abstract: For the first time in a wide temperature range, the rheology of aqueous solutions of oligo-and polysaccharides obtained by the method of combined fractionation from the secondary phytomass of apple pomace and albedo pomelo has been studied. The values of the freezing point have been determined and the possibility of the practical use of oligosaccharides as components of special-purpose preparations in liquid dosage form has been shown. On the basis of oligosaccharides obtained by the method of combined fractionation from the secondary phytomass of apple pomace and albedo pomelo, cryophylactic media have been created for the first time, possessing physicochemical stability in a wide temperature range. The main rheological and temperature characteristics of the obtained compositions have been studied and the possibility of the practical use of oligosaccharides as components of medical preparations for special purposes in liquid dosage form has been shown.

Abstract: An innovative method has been developed and an installation has been created for obtaining pectin polysaccharides in a dynamic mode under the influence of high pressure. The process of degradation of protopectin at various pH values pH of the hydrolyzing agent was studied using the example of sunflower baskets. It has been established that the use of the new method makes it possible to obtain high-quality target products with a high yield in gentle conditions. The possibility of combining the stages of hydrolysis-extraction and fractionation has been demonstrated, which makes it possible to control the process of obtaining pectic polysaccharides in the direction of obtaining substances with specified physicochemical parameters.

Abstract: High molecular weight compounds with organophosphorus backbones are usually obtained by polycondensation of phosphorus-containing monomers, leading, most often, to products of low molecular weight at low yields. This fact is explained [1] by several reasons: a decrease in the reactivity of the second functional group of the monomer after the first one has reacted; the possibility of the formation of cyclic compounds; hydrolytic instability of the phosphorus-heteroatom bond (usually P-O, P-N), etc.

Abstract: The achievements and discoveries of chemical science have firmly established themselves in all branches of humanity. One of the most significant chemistry possibilities is the polymerization and polycondensation of compounds, which, in turn, are methods for producing polymers. Polymers are high molecular weight compounds consisting of many units (monomers) linked by chemical bonds. Unique polymer compounds are the basis of plastics, chemical fibers, rubber, paints, and varnishes, adhesives [8]. Polymers are used for the manufacture of removable prostheses, materials for fillings and inlays, orthodontic appliances, artificial teeth, dental implants, as well as in the creation of artificial heart valves, artificial kidney devices, artificial circulation, artificial heart [6].

Abstract: The study of local dissipative processes by the method of free-damped torsional oscillations excited in polyvinyl alcohol (PVA) showed the presence of three loss peaks in the internal friction spectrum in different temperature ranges of this spectrum [1].

Abstract: We present here a small series of compounds designed to modify the polymer chain of various polyurethanes in order to introduce a structural fragment with the ability of thermally-triggered reversible covalent interactions. Bismaleimides (2a-2e) were synthesized from commercially available aromatic and aliphatic symmetric diamines (1a-1e) and were further introduced into the Diels-Alder reaction with furfuryl alcohol as dienophiles. The Diels-Alder adducts (3a-3e) were obtained as a mixture of endo- and exo-isomer. The presence of symmetrical hydroxyl groups in the structure of the obtained compounds makes them suitable as chain extenders of low molecular weight diisocyanate prepolymers. The presence of a thermally reversible Diels-Alder reaction adduct in the structure of potential chain-extenders opens a possibility to create unique materials with self-healing properties. All compounds obtained were characterized by ¹H, ¹³C NMR, ESI-HRMS, and IR spectroscopy. The thermochemical parameters of the reverse Diels-Alder reaction were established using DSC analysis.