Research changes in the properties of butadiene-nitrile rubber under various aging conditions

This article represents the results of a study of changes in the properties of vulcanizates based on BNR-18 butadiene-nitrile rubber containing as stabilizers the experimental spatially hindered phenols Stafen, CO3, CO4, and industrial antioxidant 6PPD, after accelerated aging (100°C 96 h) and aging under full-scale exposure in extreme climatic conditions of the Republic of Sakha (Yakutia) during 2 years. In winter, the air temperature reached—48°C, in summer—+36.1°C. It is shown that the experimental sterically hindered phenols more effectively under natural exposure conditions. They are characterized by the most stability in terms of strength throughout the entire exposure period. Under conditions of accelerated aging, the vulcanizate containing the industrial antioxidant 6PPD is characterized by the greatest stability of physical and mechanical properties. According to the viscoelastic characteristics obtained in the dynamic loading mode, the contribution of the presented stabilizers in maintaining resistance to temperature and deformation effects compared with unstabilized rubber is confirmed.

STUDY OF THE COMPATIBILITY OF S-CONTAINING PHENOLIC ANTIOXIDANT ADDITIVES AND OILS FOR TWO-STROKE ENGINES

Двухтактные двигатели за счет простоты своей конструкции, небольшого количества деталей и компактности пользуются большим спросом во многих отраслях, преимущественно для садовой техники и мотоциклов. В таких двигателях используется бензо-масляная смесь для создания масляной пленки, обеспечения достаточной смазки трущихся деталей и защиты их от коррозии. К современному моторному маслу для двухтактного двигателя существует ряд требований: полное выгорание без образования кокса, золы, отложений, хорошее растворение и перемешивание с топливом, противоизносные, антикоррозионные, смазывающие свойства при высоких температурах. Одновременного выполнения всех требований достичь представляется проблематично. Производители моторных масел используют различные присадки, улучшающие функциональные свойства масел. Известно, что содержание присадки в масле может достигать 3%. В настоящей статье рассматривается возможность использования S-содержащих пространственно-затрудненных фенолов как многофункциональных присадок. Эти вещества обладают высокой антиокислительной активностью за счет своего строения, благодаря которому замедляются процессы окисления. В качестве объекта сравнения были взяты показатели базовых масел, полученные при исследовании низкотемпературных свойств, кинематической вязкости и определении индекса вязкости. Низкотемпературные свойства присадок в смеси с маслом показали возможность использования этих веществ и в качестве пеногасящей присадки. Результаты исследования кинематической вязкости масел с присадками показали небольшое увеличение адсорбционной способности масла на деталях двигателя. Использование S-содержащих пространственно-затрудненных фенолов в составе смазывающей композиции представляется целесообразным. По исследуемым показателям можно видеть, что данные соединения совместимы с базовыми маслами. Two-stroke engines, due to their simplicity of design, a small number of parts and compactness, are in great demand in many industries, mainly for garden equipment and motorcycles. These engines use a petrol-oil mixture to create an oil film, ensure sufficient lubrication of rubbing parts and protect them from corrosion. There are a number of requirements for a modern engine oil for a two-stroke engine: complete burnout without the formation of coke, ash, deposits, good dissolution and mixing with fuel, antiwear, anti-corrosion, lubricating properties at high temperatures. It seems problematic to achieve the simultaneous fulfillment of all requirements. Motor oil manufacturers use a variety of additives to improve the performance of oils. It is known that the additive content in oil can be up to 3%. This article discusses the possibility of using S-containing sterically hindered phenols as multifunctional additives. These substances have high antioxidant activity due to their structure, due to which oxidation processes are slowed down. As an object of comparison, the indicators of base oils were taken, obtained in the study of low-temperature properties, kinematic viscosity and determination of the viscosity index. The low-temperature properties of the additives mixed with oil have shown the possibility of using these substances as a defoaming additive. The results of studying the kinematic viscosity of oils with additives showed a slight increase in the adsorption capacity of the oil on engine parts. The use of S-containing sterically hindered phenols in the composition of the lubricating composition seems to be expedient. According to the studied indicators, it can be seen that these compounds are compatible with base oils.

Increased Elasticity Modulus of Polymeric Materials Is a Source of Surface Alterations in the Human Body

The introduction of alloplastic materials (meshes) in hernia surgery has improved patient outcome by a radical reduction of hernia recurrence rate, but discussion about the biocompatibility of these implanted materials continues since observations of surface alterations of polypropylene and other alloplastic materials were published. This study intends to investigate if additives supplemented to alloplastic mesh materials merge into the solution and become analyzable. Four polypropylene and one polyester alloplastic material were incubated in different media for three weeks: distilled water, saline solution, urea solution, formalin, and hydrogen peroxide. No swelling or other changes were observed. Infrared spectroscopy scanning of incubated alloplastic materials and NMR studies of extracted solutions were performed to investigate loss of plasticizers. The surface of the mesh materials did not show any alterations independent of the incubation medium. FT-IR spectra before and after incubation did not show any differences. NMR spectra showed leaching of different plasticizers (PEG, sterically hindered phenols, thioester), of which there was more for polypropylene less for polyester. This could be the reason for the loss of elasticity of the alloplastic materials with consecutive physically induced surface alterations. A mixture of chemical reactions (oxidative stress with additive leaching from polymer fiber) in connection with physical alterations (increased elasticity modulus by loss of plasticizers) seem to be a source of these PP and PE alterations.

Tuning the Dynamic Fragility of Acrylic Polymers by Small Molecules: The Interplay of Molecular Structure

This report studied changes in dynamic fragility (m) of poly(butyl methacrylate) (PBMA) by introducing guest hindered phenols capable of forming double or triple intermolecular hydrogen bonds (inter-HBs) per molecule with...

Synthesis, Redox Properties and Antibacterial Activity of Hindered Phenols Linked to Heterocycles

A series of benzotriazole, cyclic amides and pyrimidine derivatives, containing 2,6-di-tert-butyl-phenol fragments, were synthesized. The redox properties of obtained compounds were studied using the cyclic voltammetry on a platinum electrode in acetonitrile. The oxidation potentials of all substances were comparable to those of BHT. The obtained compounds were tested for their antibacterial activity, and N-(2-(3,5-di-tert-butyl-4-hydroxyphenyl)-2-oxoethyl)isatin (32 μg/mL) exerted good activity against Staphylococcus aureus.

Bi-functional sterically hindered phenol lipid-based delivery systems as potential multi-target agents against Alzheimer's disease via an intranasal route

New lipid-based nanomaterials based on sterically hindered phenols were developed as potential drugs against Alzheimer's disease via intranasal administration.