The article presents the results of studying surface properties of bast fibers (Cannabis sativa L.) before and after exposure to arc sliding plasma. It was shown that in the process of plasma modification, plasma chemical etching processes occur on the surface of the material, ensuring the formation of active reaction centers. X-ray phase analysis demonstrated that after plasma exposure the processes of redistribution of the monoclinic and triclinic phases of cellulose on the surface of the material occur and the reflections of the triclinic phase shift towards smaller angles, indicating an increase in the interplanar distances between cellulose chains. IR spectroscopic studies revealed new oxidized functional groups on the surface. The appearance of new hydrophilic groups on the fiber surface, as well as the modification of the surface of hemp fibers (splitting, increased porosity, etc.), led to an increase in their wettability, which can provide better adhesive interaction with the components of the composite material.

A promising direction in polymer material processing is the development of self-reinforced polymer composites (SRPMs), representing a relatively new group of composite materials. The self-reinforcement method allows for materials of one polymer to be combined with different molecular, supramolecular, and structural features. The high adhesive and mechanical properties of SRPMs are due to the formation of a homogeneous system with no inter-phase boundary. Moreover, self-reinforcement considers the possibility of using polymer waste to create high-strength composites, which reduces the environmental load. In the current work, the phase composition, structure, and properties of SRPMs based on polytetrafluoroethylene (PTFE) were studied. SRPMs were prepared by mixing industrial and regenerated PTFE powders and then subjected to pressing and sintering. Two types of regenerated PTFE were used for the SRPM preparation: a commercial PTFE of the TOMFLON^TM trademark and mechanically grinded PTFE waste. The degree of crystallinity of the obtained materials (41–68%) was calculated by XRD analysis; the crystallite size was determined to be 30–69 nm. Thermal analysis of the composites was carried out by the DSC method in the temperature range of 25–370 °C. The characteristics of thermal processes in self-reinforced composites correlate with the data from structural studies of XRD and FTIR analyses. The results of dynamic mechanical analysis showed that the introduction of regenerated PTFE powder into an industrial one increased the elasticity modulus from 0.6 GPa up to 2.0–3.1 GPa. It was shown that the phase state of the SRPMs depended on the method of processing polymer waste (the type of regenerated PTFE) that determined the heat resistance and mechanical properties of the obtained composite material.

The study is conditioned by the need to improve the operational reliability of underground trunk pipelines. This is primarily due to the active development of pipeline transportation of hydrocarbons and increasing the raw material potential of the Russian Federation. During operation at low temperatures, the accumulated moisture can cyclically freeze-melt, expand and mechanically damage the waterproofing. An effective method is modification of the atmospheric pressure sliding arc in plasma, which provides a high degree of modification without deterioration of the strength and optical properties of the films, due to the absence of vacuum equipment and uniformity of modification of the polymer film surface.

Polyethylene (PE) films are widely used as waterproofing materials on the surfaces of metal pipelines. Poor adhesion of PE films to a metal substrate reduces durability, leading to shorter service life and higher economic costs. The current research aims to study the modification of PE films in atmospheric pressure gliding arc plasma (GAP). The adhesion properties of the modified films were investigated using the contact angle method and adhesion work calculations. During the modification process, the GAP treatment duration and deflector nozzle angle of attack were optimized to 10 s and 135°, respectively. It was established that the adhesion work increased from 62.1 to 141.3 mJ/m² after 10 s GAP modification compared to untreated PE. GAP modifying of PE films for 30 s or more is impractical, as the increase in the adhesion work ceases after that. It was found that surface roughness R_max increased by up to 4.1 times after 10 s GAP modification compared with nontreated PE. The PE films acquired hydrophilic properties after plasma modification, due to changes in the polymer surface’s chemical structure. The results of IR spectroscopy studies indicated oxidation of the film surface, an increase in the concentration of surface polar groups (-COOH, OH, C=O), and the formation of double bonds (C=C), which led to improved adhesive properties. A study of the electret properties showed that the observed decline and subsequent stabilization of values occurred within the first 24 h. Mechanical tests indicated improved performance of the GAP-modified PE films compared to the non-treated ones in the PE–mastic–PE and PE–mastic–steel systems. Due to their enhanced contact properties, the modified PE films are of interest as a base material for creating waterproofing materials.

Titanium alloys are widely used in medicine due to their unique properties, including inertness with respect to living tissues, light weight, high strength, and impact toughness. For successful implementation, titanium alloy implants should possess high wear resistance and hydrophilicity. This article investigates the surface modification process of VT-1 and VT-6 titanium alloys by electron-beam processing (EBP). The EBP effect on the modified surface′s wear resistance, roughness, and hydrophilicity was analyzed. The specimens were made by machining them at a CNC turning center. The specimen surfaces were modified at the SOLO facility by a submillisecond modulated electron beam with a controlled power density of thermal impact, allowing it to reach and stabilize 1400 °C in 400 µs and then maintain it on the surface for 600 µs. A friction machine with a counterbody was used to study the wear resistance of the specimen surface. The study revealed that EBP reduces the roughness parameters of the surface. EBP also decreases the contact angle of wetting, indicating an increase in hydrophilicity compared to the original surface. Experimentally, it was shown that the formation of a nanostructure consisting of needle-like α-strips induced by EBP improves the wear resistance of the surface layer.