Low-temperature Plasma Modification Research Articles

Enhancing Graphene Nanoplatelet Reactivity through Low-Temperature Plasma Modification.

Graphene-based materials have great potential for applications in many fields, but their poor dispersion in polar solvents and chemical inertness require improvements. Low-temperature plasma allows the precise modification of materials, improving the physicochemical properties of the surface and thus creating the possibility of their potential use. Plasma treatment offers the possibility of introducing oxygen functional groups simply, rapidly, and in a controlled way. In this work, a systematic investigation of the effect of plasma modification on graphene nanoplatelets has been carried out to determine the optimal plasma parameters, especially the exposure time, for introducing the highest amount of oxygen functional groups on a surface. Different gases (O2, CO2, air, Ar, and C2H4) were used for this purpose. The chemical nature of the introduced oxygen-containing functionalities was characterized by X-ray photoelectron spectroscopy, and the structural properties of the materials were studied by Raman spectroscopy. The plasma-induced changes have been shown to evolve as the surface functionalities observed after plasma treatment are unstable. The immersion of the materials in liquids was carried out to check the reactivity of carbons in postplasma reactions. Stabilization of the material's surface after plasma treatment using CH3COOH was the most effective for introducing oxygen functional groups.

Технология и результаты изучения взаимодействия поверхности с потоком заряженных частиц низкотемпературной плазмы

An analysis of approaches to studying the interaction of the surface with a stream of charged particles is presented in order to increase the efficiency of the process of low-temperature plasma modification of the surface layer. The results of the analysis showed that it is theoretically difficult to study the interaction, therefore, it is interesting to study it empirically using electrochemistry methods that allow us to investigate the phenomena of mixing and spreading of a liquid placed on the surface caused by molecular interaction processes. An off-the-shelf technology for studying surface interaction for charged particles flow in a low-temperature plasma has been found. The technology is based on the surface interaction for a particle flow simulator, using an aqueous 3,0 % NaCl salt solution. During the course of studying, it was found, firstly, that the results of interaction are actively influenced by chemical processes between the surface and the ions of the solution, depending on the value of the potential of the electric field applied to the surface, as well as due to its microrelief, and secondly, that the main boundary process running under surface interaction and solution is adsorption. The data of the analysis of the effects of exposure to the plasma surface are presented. They proved the reliability of study results, since the course of chemical and adsorption processes also take place. In general, the materials presented in the article allowed making conclusion that the developed technology makes it possible to determine the conditions that ensure an increase in the efficiency of the low-temperature plasma modification process contributing to the improvement of both surface (electrochemical) and volumetric (physical mechanical and electrophysical) properties if it is used either in the initial state or in the state changed by plasma particles.

Effect of Low-Temperature Plasma-Modified Carbon Fibers on Impact Load Damage of Low-Density Oil-Well Cement.

After large-scale exploitation of conventional oil and gas resources, most remaining resources are in highly depleted zones, where the fracture pressure of the formations is greatly reduced. Low-density oil-well cement prevents wellbore and formation fractures by reducing annular liquid column pressure and is one of the most commonly used cements in the oil and gas industry. However, cement sheaths made of low-density oil-well cement can be easily damaged due to the impact load generated during the well completion process. Incorporating carbon fibers into the cement matrix can effectively enhance the performance of cement sheaths. To ensure that carbon fibers can be closely combined with the cement matrix, low-temperature plasma modification technology was used in this study to pretreat the fibers. The mechanical properties of low-density oil-well cement incorporated with unmodified or modified carbon fibers were studied in detail under an impact load. The results of X-ray photoelectron spectroscopy revealed that the content of hydrophilic groups on the surface increased from 18.3 to 60.3% after the plasma treatment. The impact test results showed that the peak strengths of the cements cured at 60 °C for 14 days with 0.3% unmodified and modified carbon fibers could reach 37.01 ± 1.7 and 62.27 ± 1.7 MPa, respectively, under the impact load, i.e., an increase of 68.25% after the carbon fibers were treated with low-temperature plasma. Similarly, the absorbed energy increased from 15.59 to 44.31 J, and the energy absorption rate increased from 25.98 to 73.85%. Low-temperature plasma modification provided hydrophilic functional groups on the surface, significantly improving the interfacial bonding between the carbon fibers and cement matrix. The strengthened interaction was beneficial to extending the bearing time under the impact load and demonstrated a positive influence on the mechanical properties related to the impact resistance.

Effect of low-temperature plasma-treated bentonite on rubber compounds properties

The influence of low-temperature plasma modification of bentonite on the dynamic-mechanical properties and vulcanization of rubber mixtures was examined. EDX, FTIR and TGA analysis were used to evaluate the filler. IR spectra of modified bentonite indicate lower intensity of the bands associated with OH groups and water. TGA confirms a smaller weight loss of samples subjected to plasma treatment, which also proves a lower water content in the mineral, confirming the effectiveness of the plasma treatment used.

The Influence of Low-Temperature Plasma Modification on Contact Interactions of Cutting Tools

The Influence of Low-Temperature Plasma Modification on Contact Interactions of Cutting Tools

Ultrasonic extraction, structural modification and gastric mucosal cells protective activity of a polysaccharide from Dendrobium denneanum

Optimize the ultrasonic extraction process of polysaccharides from Dendrobium denneanum by Response surface design (RSM). The main polysaccharide (DP40) from was separated by anion exchange chromatography, and its structure was modified by low-temperature plasma. The results showed that the polysaccharide extraction rate of ultrasonic was 22.98 ± 0.97%, which was significantly higher than water extraction method(P < 0.05). FT-IR showed that low-temperature plasma modification could improve the water solubility and OH content. NMR showed that the 1 → 6 glycosidic bonds of DP40 are transformed into 1 → 4 glycosidic bonds and 1 → 3 glycosidic bonds, and the α-configuration sugar ring is transformed into β-configuration after plasma treatment. SEM and TEM analysis showed that the morphology of modified DP40 changed from layered porous network structure to smooth morphology, and bulged into semicircular particles, and the degree of cross-linking of surface molecules increased. The results of biological activity experiments indicated that the modified polysaccharide (500–1000 μg·mL−1) can significantly improve the survival rate of GES-1 cells (p < 0.01). Compared with the untreated group, the high concentration of 1000 μg·mL−1 DP40-plasma could not only reduce ROS by 14.5% (p < 0.05) and MDA by 27.45% (p < 0.05), increase SOD activity by 28.27%, but also reduce cytokines (IL-8, TNF-α, IL-1β) by 31.82% (p < 0.05), 33.23% (p < 0.05) and 21.97% (p < 0.05), respectively. At the same time, low-temperature plasma modification can effectively reduce the caspase 3 activity, prevent cell apoptosis, and protect gastric mucosal cells from ethanol damage. Therefore, low-temperature plasma modification can improve the biological activity of DP40 polysaccharide by altering its structural characteristics. The results provide a new idea for the application of low-temperature plasma modification in biomacromolecules.

Low-temperature plasma modification, structural characterization and anti-diabetic activity of an apricot pectic polysaccharide

To fully research the anti-diabetic activity of apricot polysaccharide, low temperature plasma (LTP) was used to modify apricot polysaccharide. The modified polysaccharide was isolated and purified using column chromatography. It was found that LTP modification can significantly improve the α-glucosidase glucosidase inhibition rate of apricot polysaccharides. The isolated fraction FAPP-2D with HG domain showed excellent anti-diabetic activity in insulin resistance model in L6 cell. We found that FAPP-2D increased the ADP/ATP ratio and inhibited PKA phosphorylation, activating the LKB1-AMPK pathway. Moreover, FAPP-2D activated AMPK-PGC1α pathway, which could stimulated mitochondrial production and regulate energy metabolism, promoting GLUT4 protein transport to achieve an anti-diabetic effect. The Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy data showed that the LTP modification could increase the CH bond content while decreasing the C-O-C/C-O bond content, indicating that LTP destroyed the C-O-C/C-O bond, which enhanced the anti-diabetes activity of the modified apricot pectin polysaccharide. Our findings could pave the way for the molecular exploitation of apricot polysaccharides and the application of low-temperature plasma.

Development and properties of active films based on potato starch modified by low-temperature plasma and enriched with cinnamon essential oil coated with nanoparticles

Potato starch dispersion was modified with low-temperature plasma (LTP) and cinnamon essential oil (CEO) was successfully loaded into mesoporous nano-silica particles (SBA-15). The SBA-15-CEO/LTP-potato starch film was prepared to explore the effects of LTP and SBA-15-CEO on the thermal stability, mechanical and physical properties of the starch-based film. The results showed that the plasma modification and SBA-15-CEO improved the thermal stability and mechanical and physical properties, as well as reduced the gas permeability of the film. Significantly, the crystal structure of the LTP- potato starch film changed after adding SBA-15-CEO. The optimized SBA-15-CEO/LTP-potato starch film (1.5 g glycerin; 0.5 g SBA-15-CEO) had the best mechanical properties and thermal stability and the lowest air permeability and hydrophilicity. Moreover, the aggregation of SBA-15-CEO decreased after LTP treatment, and the appearance of irregular and rough fractured surfaces was also alleviated. After LTP modification, the agglomeration of SBA-15-CEO in the film was solved to some extent. The addition of SBA-15-CEO alleviated the problem of starch dehydration and film cracking caused by LTP modification. Therefore, LTP is a simple and environmentally friendly method to improve the properties of potato starch film.

Effects of low-temperature plasma modification on properties of CEO-SBA-15/potato starch film

A potato starch solution was modified by low-temperature plasma (LTP), and cinnamon essential oil (CEO) was incorporated with mesoporous silica nanoparticles (SBA-15) to obtain modified CEO-SBA-15/potato starch film. The mechanical properties, physical properties and gas resistance properties of the films were measured when the LTP treatment time was 0 min, 3 min, 6 min, 9 min, 12 min and 15 min. LTP treatment significantly increased the tensile strength and elongation at break of the material, and decreased the air permeability and hygroscopicity, until LTP treatment time was 9 min. The SEM results showed that circular cracks appeared on the surface of the potato starch granules after the plasma treatment. Notably, the number of circular cracks increased as the processing time increased. This may be beneficial to the effect of LTP on starch internal structure. The film had the optimal water vapor transmittance rate (12.05 g/(m2·h)), opacity (3.15%), tensile strength (3.55 MPa), and oxygen transmittance rate (5.129 × 10−15 cm2 s−1 Pa−1) at a treatment time of 6 min. Significantly, the LTP-modified potato starch improved the performance of film and reduced the aggregation of nanoparticles in the film.

The effect of pressure in the working chamber of a processing unit on the quality indicators of the composite structure formed in the metal product surface layer at low-temperature plasma modification

The paper proposes an approach to increasing the efficiency of plasma modification of the metal product surface layer based on the study of the effect of pressure in the working chamber of a technological unit on its course and outcomes. It was found that there is such influence, and it is manifested in a heat flow direction change and leads to the intensification of either heat conduction (with increasing pressure), or heat transfer and radiation from the surface (with decreasing pressure). In the first case this leads to the formation of the most compacted composite structure in the surface layer, and to the transition layer formation between the structure and the main material of the product. In the second case the compaction of the surface layer is minimal, no transition layer is formed. The pressure change effect mechanism associated with the violation of the dynamic equilibrium between adsorbed and desorbed particles on the product surface when changing the temperature regime has been identified. It is shown that after switching off the plasma, it is necessary to control the heat flow propagation, and that the course of the lag temperature curve can serve as an operational indicator of the control quality.

Substantiation of the technology for controlling the process of low-temperature plasma modification of metal product surface layer by the electrical signal parameters

Substantiation of the technology for controlling the process of low-temperature plasma modification of metal product surface layer by the electrical signal parameters

Effect of Non-Equilibrium Low Temperature Plasma on Genuine Leather Adhesion Properties of Special Purpose Footwear Upper to Molding Compositions with Polyurethanes Base

Roughing operation is used to improve the adhesive properties of footwear upper to footwear bottom polyurethane compositions in the manufacture of special purpose footwear with an upper made of genuine leather by the injection molding method of attachment. Roughing operation is an operation of coating removal and partial removal of the front layer from the protracted edge of footwear upper workpiece. This operation has a disadvantage, it often causes technological defects. A method for increasing the adhesive properties of genuine leather special purpose footwear upper workpiece with a front layer by means of non-equilibrium low temperature plasma modification and technological scheme that allows this operation to be integrated into the production process are considered in the article.

Realization of electrical signal monitoring of metal surface modification by means of low-temperature plasma treatment

The paper shows good prospects of modifying the working surfaces of metal products by low-temperature plasma treatment. We suggest a treatment monitoring method based on the recording of signals that arise in the electrical circuit of the processing unit and present the results of this approach realization. The study substantiates the expediency, assesses possibility, and shows the efficiency of controlling the low-temperature plasma modification based on the correction of its operating parameters according to monitoring data.

Оценка возможностей улучшения обрабатываемости изделий инструментом из быстрорежущей стали с модифицированной рабочей частью

There are presented results of the comparative operation of two high-speed steel drill types: common ones and those with the working part modified by low-temperature plasma effect. A possibility to improve product machinability according to the criterion of productivity at the expense of the durability period increase of modified drills is shown. &#x0D; There are formulated requirements to the results of low-temperature plasma modification ensuring tool life increase.

Low-Temperature Plasma Modification of Styrene-Butadiene Block Copolymer Surfaces for Improved Adhesion-A Kinetic Approach.

This paper proposed a kinetic model that can describe the changes in the adhesion properties of styrene–butadiene (SBS) block copolymer surfaces under the influence of low-temperature plasma treatment. As a measure of these changes, the peel strength of joints formed between the copolymer surface and the polyurethane adhesive was chosen. Five types of low-temperature low-pressure RF plasma, two inert plasmas (Ar and He), and three reactive plasmas (O2, CO2, and CCl4) were tested. It was found that for all these types of plasma, the peel strength with the plasma treatment time first increases rapidly reaching a maximum value, and then there is a visible decrease in peel strength, after which the peel strength increases again. This dependence of the peel strength on the plasma treatment time is very well described by the proposed model, which considers three processes: (1) the generation of radical states followed by the creation of functional groups involved in the adhesive bonding process, (2) the surface cross-linking that decreases the concentration of these functional groups, and (3) the formation of nano-roughness. The model analysis revealed differences between the action of reactive and inert plasmas in the SBS surface cross-linking mechanism and preferential etching process, as well as differences in the generation of radical states between the O2 plasma (electron process) and other plasmas tested (ionic processes).

Nanohydroxyapatite adhesion to low temperature plasma modified surface of 3D-printed bone tissue engineering scaffolds - qualitative and quantitative study

Biodegradable 3D-printed polycaprolactone scaffolds for bone tissue engineering applications have been extensively studied as they can provide an attractive porous architecture mimicking natural bone, with tunable physical and mechanical properties enhancing positive cellular response. The main drawbacks of polycaprolactone-based scaffolds, limiting their applications in tissue engineering are: their hydrophobic nature, low bioactivity and poor mechanical properties compared to native bone tissue. To overcome these issues, the surface of scaffolds is usually modified and covered with a ceramic layer. However, a detailed description of the adhesion forces of ceramic particles to the polymer surface of the scaffolds is still lacking. Our present work is focused on obtaining PCL-based composite scaffolds to strengthen the architecture of the final product. In this manuscript, we report qualitative and quantitative evaluation of low temperature plasma modification followed by detailed studies of the adhesion forces between chemically attached ceramic layer and the surface of polycaprolactone-nanohydroxyapatite composite 3D-printed scaffolds. The results suggest modification-dependent alteration of the internal structure and morphology, as well as mechanical and physical scaffold properties recorded with atomic force microscopy. Moreover, changes in the material surface were followed by enhanced adhesion forces binding the ceramic layer to polymer-based scaffolds.

Low-temperature plasma modification of carbon nanofillers for improved performance of advanced rubber composites

In modern polymer industry, there still is a room for new generations of fillers capable of enhancing the performance of composite materials. Currently, much effort is being put into a process of improving mechanical properties of elastomer materials. In this work, multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GnPs) were modified with silane, titanate, or zirconate using plasma treatment, in order to apply them as fillers for styrene/butadiene rubber. Following its modification, filler surface was analyzed: Surface free energy (SFE) was measured with tensiometry, and micromorphology and chemical composition were studied with scanning electron microscopy–energy-dispersive spectroscopy (SEM–EDS), while elemental composition and bonding were assessed with X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Low-temperature oxygen plasma activation of MWCNT fillers leads to a significant increase in the SFE polar component, with the same effect being much weaker for GnP fillers. Grafting silanes, zirconates, and titanates on activated filler surface results in a decrease in SFE polar component—surface oxygen-containing active groups react with silane/zirconate/titanate molecules. Fillers modified in this way exhibit different micromorphology and surface chemical composition what is revealed with the SEM–EDS, ToF-SIMS, and XPS techniques. As the ultimate step, either MWCNT or GnP rubber nanocomposites were manufactured using the modified fillers with their mechanical properties and cross-link density being studied. Filler modification resulted in substantial changes both in composite performance, and in its cross-linking density. In the case of modified filler containing composites, improved tensile strength and elongation at break were observed.

Plasma technologies application for building materials surface modification

Low-temperature plasma modification of LiYF4 crystal surface in Helium atmosphere caused microhardness decreasing and increasing of roughness of crystal surface. The change of microhardness and morphology is a possible result of Fluorine outgoing from material structure due to heating of surface and plasma chemical reactions and ingoing of Oxygen. As a result of exchange and diffusion processes crystal surface structure become more crumbly, its morphology and mechanical properties change.

Effect of Accelerated Ageing on Ballistic Textiles Modified By Plasma-Assisted Chemical Vapour Deposition (PACVD)

The functionalisation of textile products and materials using the low temperature plasma technique is increasingly used in industrial practice, mainly because of the many benefits, often unattainable with the use of other techniques. The study focused on the modification of the composite textile materials - sheets of Ultra High Molecular Weight Polyethylene (UHMWPE) fibres (Dyneema ® SB51) by applying the surface deposition of silicone-like polymer in an environment of low temperature plasma. The aim of this study was to evaluate changes in the mechanical and physical properties of modified ballistic textiles un der simulated storage conditions in accelerated time. Based on experiences in planning the research on accelerated aging, a test programme was developed for the assessment of changes during the aging process in ballistic fibrous materials under various environmen tal conditions. The process of low temperature plasma modification affected the mechani cal properties of the ballistic composite textile materials during the accelerated ageing using temperature or temperature and humidity. The effect of the modification varied with the mechanical properties investigated.

High-frequency low-temperature plasma intensification of physicochemical processes during cellulose treatment

The effect of a high-frequency low-temperature plasma of reduced pressure on the amorphouscrystalline structure and absorption-kinetic and capillary properties of cellulose are investigated. The following have been established: a change in the morphological structure of cellulose fiber, intensification of adhesion and the kinetics of capillary absorbability due to high-frequency low-temperature plasma modification of cellulose. The data obtained permit the conclusion on a possible increase in cellulose activity in the heterogeneous process of its treatment.