Differential scanning calorimetry and X-ray diffraction at wide and small angles were used to examine the biodegradable composites of poly-3-hydroxybutyrate with chitosan, produced by mixing of these

This study is devoted to the establishment of the connection of antibacterial surface properties with the structure and composition of coatings based on a styrene-butadiene thermoplastic elastomer with polylactide and antibacterial agents: tetramethylenediethylenetetramine or distearyldimethylammonium chloride. It is shown that the mechanism of antibacterial action of the composition is based on the leaching (release) of antibacterial agents in an aqueous environment together with microorganisms. The effect depends on the structural organization of the coating, which accelerates their leaching and is enhanced by the inclusion of antibacterial agents in the hydrolyzed phase of the polylactide, which is localized in the styrene-butadiene matrix around the polystyrene domains. The features of the structure of the films and coatings are established by scanning electron microscopy (SEM), using a paramagnetic probe, physical and mechanical parameters, and by studying the laws of thermal destruction using thermogravimetry.

The melting and thermal degradation of porous polylactide have been studied by differential scanning calorimetry and thermogravimetric analysis. The pores are formed from a solution of...

Objectives. To discuss the main problems and prospects of creating modern osteoplastic materials based on polymer compositions used for bone surgery.Methods. This review summarizes the research works devoted to the creation of materials used for bone implants and issues involved in their practical testing, as well as analyzes and synthesizes data of scientific articles on the following topics: rationale for the use of biodegradable materials in bone surgery; biodegradation and bioreparation bone graft processes; requirements for degradable polymer composite materials (PCMs) for biomedical applications; overview of polymeric materials suitable for use in implant practice; impact of modifications of the PCM on the structure and biological activity of the material in biological media; effect of exhaust and heat treatment on the molecular structure of polyalkanoates.Results. The most promising biodegradable resorbable materials for reparative bone surgery to date are compared. The requirements for these types of materials are formulated and a rationale for their use is provided that takes into account the advantages over traditional metal and ceramic implants. The features of the kinetics and mechanism of biodegradation of implants in their interaction with the bone biological environment of the body from the moment of implant insertion to complete wound healing are considered. As a result of the analysis, factors that may affect the activity of implant decomposition and methods of adjusting the decomposition rate and mechanical characteristics of the material, such as chemical functionalization, the creation of block copolymers, the inclusion of fibers and mineral fillers in the composite, as well as heat treatment and extraction of the composite at the manufacturing stage, were identified. Among the main factors, the influence of the structure of the composite material on its biological activity during interaction with biological media was evaluated. Of polymer materials, the main attention is paid to the most common biodegradable polymers widely used in medicine: polyhydroxybutyrate (PHB) of microbiological origin, polylactide (PLA) and other polymers based on polylactic acid, polycaprolactone (PCL). The effect of their modification by such additives as hydroxyapatite (HAP), chitin and chitosan, and beta-tricalcium phosphate (β-TCF) is considered. Materials based on PHB are concluded as the most promising due to their complete biodegradability to non-toxic products (carbon dioxide and water) and good biocompatibility. Nevertheless, existing compositions based on PHB are not without disadvantages, which include fragility, low elasticity, unstable behavior under high-temperature exposure during processing, implant molding, sterilization, etc., which requires improvement both in terms of polymer modification and in terms of composition of compositions.Conclusions. The review considers approaches to achieving the properties of materials required for perfect implants. The main requirements for implants are optimization of the time of resorption of the osteoplastic matrix, facilitating the resorption of the osteoplastic matrix synchronized in time with the process of bone regeneration. To achieve these requirements, it is necessary to apply technologies that include modification of polymer composite materials by affecting the chemical composition and structure; introduction of fillers; use of chemical functionalization, orientation extraction, heat treatment. The success of using bone materials based on biodegradable polymers is based on an accurate understanding of the mechanism of action of various components of the implant composition and strict compliance with the tightening regulatory requirements of implantation technology.

The effect of fillers, polysulfone and polyetherimide, on the mechanism and kinetics of the thermo-oxidative degradation of a composition based on an epoxy oligomer cured with 4,4'-diaminodiphenyl sulfone which proceeds under heating in the nonisothermal regime is studied. A relationship is revealed between the structure of the composition and the mechanism and kinetic parameters of the process, on one hand, and the chemical nature of the filler, on the other hand. Mechanistic and kinetic features of the nonisothermal degradation of the epoxyamine composition are ascertained by the thermoanalytical method using differential scanning calorimetry. The kinetic parameters of the process are assessed by an analysis of thermokinetic curves in terms of thermokinetic models and the examination of oxidation products. Depending on the filler nature and composition structure, reactions involving bonds of interjunction chains and junctions of the network of the epoxy polymer as well as radical reactions of the active centers of the filler occur in the polymer during thermal oxidation. An increase in the network density and the localization of the filler determine the contribution of the diffusion factor, decrease the rate of thermo-oxidative degradation of interjunction chains, and increase the rate of breakdown of network junctions.

Отмечена возможность повышения продуктивности семян путем воздействия на них электромагнитного поля. Рассмотрены теоретические и практические предпосылки создания экспериментальной лабораторной установки для предпосевной обработки семян низкочастотным электромагнитным полем и достижения магнитобиологического эффекта. (Цель исследования) Изучить влияние низкочастотного электромагнитного поля на состав и свойства семян зерновых культур. (Материалы и методы) Применялись стандартные излучатели с вариативностью магнитной индукции 3-75 миллитесла, частотой излучения 1-100 Герц, обеспечивающие требуемые параметры воздействия на партию семян. (Результаты и обсуждение) Исследовали влияние магнитного воздействия на всхожесть, энергию прорастания, физико-химические свойства семян при варьировании параметров низкочастотного электромагнитного поля. Проведен анализ зависимости качества воздействия от параметров работы установки и массы семян различных зерновых культур от 10 до 500 г. На этой основе выбраны режимы и создана рабочая программа облучения, обеспечивающая высокую эффективность воздействия на показатели всхожести, прорастания и развития семян. (Выводы) Изучено влияние низкочастотного электромагнитного поля на состав и свойства зерна. Разработана экспериментальная лабораторная установка с источниками низкочастотного электромагнитного поля, обоснованы режимы излучения. Магнитобиологический эффект предпосевной обработки промышленной партии зависит от вида и сорта культуры, активации в клетке биологического комплекса, инициирующего развитие проростка, качества и влажности семян, наличия на поверхности микроорганизмов, в том числе патогенных, источников и энергетических параметров облучения. Определены параметры низкочастотного электромагнитного поля: магнитная индукция от 3 до 75 миллитесла, частота 10-16 Герц, масса семян от 10 до 500 граммов. Эти параметры будут использованы при создании промышленной установки для подготовки семенного материала и улучшения его посевных свойств.