Influence Of Plasma Treatment Research Articles

Influence of plasma treatment on the oxygen reduction reaction performance of graphene-based materials

Carbon materials are of outstanding interest for use in energy sources. One of the latest achievements in improving their specific characteristics is the doping of carbon materials with various heteroatoms. However, the mechanisms that lead to improved performance remain unexplored. In this study, we investigated the influence of structural defects and incorporated heteroatoms on the oxygen reduction reaction (ORR) of highly oriented pyrolytic graphite and carbon nanowalls. Controllable modification in DC plasma in an atmosphere of nitrogen, oxygen and air was used for the incorporation of heteroatoms. We found that treatment in the air atmosphere leads to the formation of most active sites due to incorporation of heteroatoms and partial amorphization of material surface. The DFT calculations reveal these active sites can’t be amplified by substitution to nitrogen atom due to insignificant sorption energy difference of *OOH group compared with undoped carbon. Existed material’s structural defects and appeared after the treatment also make a significant contribution to the obtained ORR characteristics. Plasma-assisted treatment under air conditions can be used for carbon nanomaterials modification for ORR application.

In Vitro and In Silico Studies of Functionalized Polyurethane Surfaces toward Understanding Biologically Relevant Interactions.

The solid-aqueous boundary formed upon biomaterial implantation provides a playground for most biochemical reactions and physiological processes involved in implant-host interactions. Therefore, for biomaterial development, optimization, and application, it is essential to understand the biomaterial-water interface in depth. In this study, oxygen plasma-functionalized polyurethane surfaces that can be successfully utilized in contact with the tissue of the respiratory system were prepared and investigated. Through experiments, the influence of plasma treatment on the physicochemical properties of polyurethane was investigated by atomic force microscopy, attenuated total reflection infrared spectroscopy, differential thermal analysis, X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and contact angle measurements, supplemented with biological tests using the A549 cell line and two bacteria strains (Staphylococcus aureus and Pseudomonas aeruginosa). The molecular interpretation of the experimental findings was achieved by molecular dynamics simulations employing newly developed, fully atomistic models of unmodified and plasma-functionalized polyurethane materials to characterize the polyurethane-water interfaces at the nanoscale in detail. The experimentally obtained polar and dispersive surface free energies were consistent with the calculated free energies, verifying the adequacy of the developed models. A 20% substitution of the polymeric chain termini by their oxidized variants was observed in the experimentally obtained plasma-modified polyurethane surface, indicating the surface saturation with oxygen-containing functional groups.

Preparation of highly dispersed silicon spheres supported cobalt-based catalysts and their catalytic performance for Fischer-Tropsch synthesis

A series of silicon spheres supported cobalt catalysts were prepared by incipient wetness impregnation followed by decomposition under treatment of glow discharge plasma with different intensities. The catalysts were characterized by X-ray powder diffraction, N2 physical adsorption-desorption, H2 temperature-programmed reduction, transmission electron microscope and Fourier-Transform Infrared spectroscopy. The Fischer-Tropsch synthesis performance were tested on a fixed bed reactor. The influence of plasma treatment on cobalt dispersion, reducibility and cobalt-support interaction were analyzed and discussed. The results showed that the plasma-treated catalysts had better catalytic performance than the calcined sample. The Co/SP-P650W catalyst showed the highest reaction activity due to the proper cobalt dispersion and higher cobalt reducibility.

Influence of Plasma Treatment on Surface Characteristics of Aluminum Alloy Sheets and Bonding Performance of Glass Fiber-Reinforced Thermoplastic/Al Composites.

This study focuses on modifying the surface of an AA 5052-H32 aluminum alloy using plasma treatment. Discharge power, exposure time, and working gas were adjusted as process parameters to improve the adhesion between the aluminum alloy and glass fiber-reinforced thermoplastic (GFRTP) polycarbonate composite. The surface composition and morphology of the aluminum alloy sheet were analyzed by X-ray photoelectron spectroscopy and scanning electron microscopy, and surface roughness and wettability were evaluated using a surface roughness-measuring instrument and contact angle goniometry, respectively. The bonding performance of GFRTP/aluminum alloy was also assessed. The surface of the aluminum alloy was subjected to chemical treatment prior to plasma treatment. The results revealed that nitrogen plasma treatment led to a substantial increase (25%) in bonding strength due to the synergistic effect of rough surface mechanical bonding and chemical bonding through functional groups between the aluminum alloy and GFRTP. However, the improvement in surface wettability by plasma treatment is time dependent and may gradually diminish over time due to the re-adsorption of hydrocarbon contamination from the surrounding air.

Influence of plasma treatment on moisture management properties of cotton/polyester knitted fabrics

Influence of plasma treatment on moisture management properties of cotton/polyester knitted fabrics

Positive Effect Induced by Plasma Treatment of Seeds on the Agricultural Performance of Sunflower

The need for efficient technologies to enhance productivity in agriculture strongly motivates research on plasma treatment of seeds and plants. In this study, the influence of plasma treatment on sunflower (Helianthus annuus L.) seeds was evidenced throughout the entire life span of the plants. The seeds were packed in a DBD reactor operated in air and treated in plasma for 10 min, using a sinusoidal voltage of 16 kV amplitude at 50 Hz frequency. Early growth observation of plants under laboratory conditions showed that, after a slower start, the plasma-treated seeds developed faster and produced taller seedlings with greater total mass as compared to the control samples. Results obtained from mature plants cultivated in the field revealed a positive effect of plasma exposure with respect to capitulum size, number of seeds per capitulum and mass per thousand seeds, resulting in a remarkable increase in crop yield. The plasma effect lasted for at least two weeks of seed storage; however, it was considerably affected by the sowing period.

The Influence of Plasma Treatment and Substrate Bias Voltage on the Bonding Properties of Carbon Fiber/Copper Composites

The Influence of Plasma Treatment and Substrate Bias Voltage on the Bonding Properties of Carbon Fiber/Copper Composites

The Influence of Plasma Treatment on the Corrosion and Biocompatibility of Magnesium.

In our study, plasma surface modification was employed to tailor the surface properties of magnesium in terms of surface chemistry, topography, and wettability. For two sets of samples, the plasma treatment involved two steps using two different gases (hydrogen and oxygen), while one set of samples was treated with one step only using oxygen. X-ray photoelectron spectroscopy (XPS) was applied to determine the surface composition, oxidation state of the elements, and the thickness of the surface oxide layer on the Mg samples after different plasma treatments. The surface morphology was characterised using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The wettability was analysed by measuring the static water-contact angles and the corrosion was evaluated using potentiodynamic measurements. The interaction of the live cells with the differently modified Mg surfaces was evaluated in terms of biocompatibility using MG-63 cells (human bone osteosarcoma cells). We have shown that a plasma surface treatment significantly decreased the carbon content and the formation of a 15–20-nm-thick MgO layer was observed. This improves the corrosion resistance, while the biocompatibility was retained, compared to the untreated Mg. A plasma surface treatment is therefore an important step in the development of novel surfaces with improved corrosion resistance for magnesium in biomedical applications.

Studying the influence of plasma treatment on the cracks formation of PDMS wrinkling through orthogonal experiment

Studying the influence of plasma treatment on the cracks formation of PDMS wrinkling through orthogonal experiment

Influence of plasma treatment on moisture management of bamboo charcoal composite fabrics for hospital application

To enhance the moisture transmission properties of hospital bed linen, a tri-layer weft knitted fabric has been developed from the fibres, like lyocell, bamboo charcoal and micro polyester, and tested for comfort properties. The tri-layer fabric exhibits good water vapour permeability, water absorbing tendency, wicking tendency and faster drying rate. To enhance these functional properties, the fabric is subjected to plasma treatment. Optimization of plasma treatment parameters is attempted by using Box-Benkhen experimental design, considering the process parameters, such as time, distance between electrodes and current. The plasma-treated and untreated fabrics are tested for moisture management properties, such as water absorbency, water vapor permeability, wickability – transverse and vertical, drying time and SEM analysis. From the test results, it is observed that the plasma-treated fabric has improved moisture management and drying properties

Eco-Friendly In Situ ZnO Synthesis on PET Fabric Using Oxygen Plasma and Plant Waste

This study presents an eco-friendly protocol for the hydrophilization of polyethylene terephthalate (PET) fabric and the in situ synthesis of ZnO particles. The alkaline medium and reducing agent for ZnO synthesis were prepared as aqueous extracts from wood ash and pomegranate peel, respectively. Due to the hydrophobic nature of the PET fabric, oxygen plasma treatment was included in the process. The influence of plasma treatment in different synthesis steps on the formation of ZnO and consequently on the morphological, colour and ultraviolet (UV) protective properties of the samples was discussed. The study showed that incorporating oxygen plasma treatment before immersing the samples in each solution for the ZnO in situ synthesis (natural alkaline medium of wood ash, zinc salt and natural reducing agent from pomegranate peel) produced PET fabric with the most uniform ZnO layer without visible cracks and the highest UV-blocking ability with a UV protection factor (UPF) of 300+. The colour measurements showed that increasing the number of plasma treatments leads to higher colour strength of the samples. Herein, a novel protocol for the production of protective PET fabrics is presented, which is also an example of a completely environmentally benign textile functionalization process.

Influence of Air Plasma Pretreatments on Mechanical Properties in Metal-Reinforced Laminated Wood

The use of wood-based materials in building and construction is constantly increasing as environmental aspects and sustainability gain importance. For structural applications, however, there are many examples where hybrid material systems are needed to fulfil the specific mechanical requirements of the individual application. In particular, metal reinforcements are a common solution to enhance the mechanical properties of a wooden structural element. Metal-reinforced wood components further help to reduce cross-sectional sizes of load-bearing structures, improve the attachment of masonry or other materials, enhance the seismic safety and tremor dissipation capacity, as well as the durability of the structural elements in highly humid environments and under high permanent mechanical load. A critical factor to achieve these benefits, however, is the mechanical joint between the different material classes, namely the wood and metal parts. Currently, this joint is formed using epoxy or polyurethane (PU) adhesives, the former yielding highest mechanical strengths, whereas the latter presents a compromise between mechanical and economical constraints. Regarding sustainability and economic viability, the utilization of different adhesive systems would be preferable, whereas mechanical stabilities yielded for metal-wood joints do not permit for the use of other common adhesive systems in such structural applications. This study extends previous research on the use of non-thermal air plasma pretreatments for the formation of wood-metal joints. The plasma treatments of Norway spruce [Picea abies (L.) Karst.] wood and anodized (E6/EV1) aluminum AlMgSi0.5 (6060) F22 were optimized, using water contact angle measurements to determine the effect and homogeneity of plasma treatments. The adhesive bond strengths of plasma-pretreated and untreated specimens were tested with commercial 2-component epoxy, PU, melamine-urea formaldehyde (MUF), polyvinyl acetate (PVAc), and construction adhesive glue systems. The influence of plasma treatments on the mechanical performance of the compounds was evaluated for one selected glue system via bending strength tests. The impact of the hybrid interface between metal and wood was isolated for the tests by using five-layer laminates from three wood lamellae enclosing two aluminum plates, thereby excluding the influence of congeneric wood-wood bonds. The effect of the plasma treatments is discussed based on the chemical and physical modifications of the substrates and the respective interaction mechanisms with the glue systems.

Effects of Atmospheric Plasma Corona Discharge on Agrobacterium tumefaciens Survival.

Soil-borne pathogenic microorganisms are known to cause extensive crop losses. Agrobacterium tumefaciens, a member of the Proteobacteria, causes the neoplastic crown gall disease in plants. Plant protection is mainly based on toxic chemicals that are harmful to the environment. The use of cold atmospheric-pressure plasma is an attractive method for microbial eradication. Its antimicrobial mechanism includes the formation of large quantities of reactive oxygen species (ROS). The advantages of eradicating bacteria using cold plasma are not needed for chemicals, short treatment, and environmental temperatures. This study examined the impact of plasma corona discharge exposure on A. tumefaciens viability, membrane permeability, relative cell size, and ROS formation. The results showed that 90 s of plasma exposure led to a reduction by four orders of magnitude when the initial concentration was 1 × 107 CFU/mL and in a dry environment. When the initial concentration was 1 × 106 CFU/mL, 45 s of exposure resulted in total bacterial eradication. In a liquid environment, in an initial concentration of 2.02 × 106 CFU/mL, there was no complete bacterial eradication even at the most prolonged examined exposure (90 s). The influence of plasma treatment on the membrane permeability of A. tumefaciens, and their possible recovery, were analyzed using flow cytometer analysis using propidium iodide (PI). When the plasma-treated bacteria were suspended in Luria–Bertani (LB) (rich medium), the PI-positive count of the plasma-treated bacteria after two hours was 12 ± 3.9%. At the 24th hour, this percentage was only 1.74 ± 0.6%, as the control (0.7 ± 0.1%). These results may indicate the repair of the plasma-treated bacteria that were suspended in LB. At the 24th hour, the relative cell size of the treated bacteria shifted to the right, to ~3 × 104 forward side scatter (FSC), about 0.5-fold higher than the untreated cells. Measurement of the ROS showed that the intracellular fluorescence of the 90-s plasma-treated cells led to significant fluorescence formation of 32 relative fluorescence units (RFU)/cell (9 × 104 fold, compared to the nontreated cells). This study showed that cold plasma is a useful method for A. tumefaciens eradication. The eradication mechanism involves ROS generation, membrane permeability, and changes in cell size.

Selection of proper matrix with plasma-treated HTPP fiber reinforced cementitious composites in terms of flexural toughness

In this study the influence of matrix type on plasma-treated high tenacity polypropylene fiber reinforced cementitious composites were investigated. The fibers were subjected to low frequency cold plasma of oxygen gas. Power rate of the generator was 50, 100 and 200 W, and duration was 0.5, 2 and 20 min. 25 × 60 × 300 mm prismatic samples were prepared with two type of matrices, and plasma-treated/untreated fibers. Scanning electron microscope was used to determine physical modifications on the fibre surface. Four point bending tests were conducted on prismatic samples. Matrices with treated and untreated fiber reinforcement were compared by means of flexural properties. Analysis of variences was applied to the plasma treated fiber reinforced groups. Test results showed that the flexural behaviour of composites was affected by plasma power and duration. There was physical modification for each plasma power and duration. The influence of plasma treatment on fiber-matrix bond properties was mainly affected by matrix type: weak matrix showed better flexural properties with low power and short duration plasma-treated fibers, whereas comparatively stronger matrix expressed greater flexural properties at higher power and longer durations when compared to untreated fiber reinforced composites.

Response of Two Different Wheat Varieties to Glow and Afterglow Oxygen Plasma.

Cold plasma technology has received significant attention in agriculture due to its effect on the seeds and plants of important cultivars, such as wheat. Due to climate change, wherein increasing temperatures and droughts are frequent, it is important to consider novel approaches to agricultural production. As increased dormancy levels in wheat are correlated with high temperatures and drought, improving the germination and root growth of wheat seeds could offer new possibilities for seed sowing. The main objective of this study was to evaluate the influence of direct (glow) and indirect (afterglow) radio-frequency (RF) oxygen plasma treatments on the germination of two winter wheat varieties: Apache and Bezostaya 1. The influence of plasma treatment on seed surface morphology was studied using scanning electron microscopy, and it was observed that direct plasma treatment resulted in a high etching and nanostructuring of the seed surface. The effect of plasma treatment on germination was evaluated by measuring the germination rate, counting the number of roots and the length of the root system, and the fresh weight of seedlings. The results of this study indicate that the response of seeds to direct and indirect plasma treatment may be variety-dependent, as differences between the two wheat varieties were observed.

Influence of Plasma Treatment on Dyeing Properties of Silk Weaves

ABSTRACT Three different mulberry silk fabrics were modified with low temperature plasma using helium and oxygen gases. Dyeing properties of plasma treated fabrics were investigated. The dye adsorption capacity of plasma treated silk samples was improved by 6–17% as compared to untreated samples in all the three varieties of silk. Surface roughness was quantitatively measured using Atomic Force Microscope (AFM). X-ray photoelectron spectroscopic study showed the formation of polar groups on plasma treated silk samples. Finally, it is concluded that the degree of plasma surface modification and dyeing properties of silk fabric are closely linked to weave and GSM of fabric.

Influence of plasma treatment on SiO2/Si and Si3N4/Si substrates for large-scale transfer of graphene

One of the limiting factors of graphene integration into electronic, photonic, or sensing devices is the unavailability of large-scale graphene directly grown on the isolators. Therefore, it is necessary to transfer graphene from the donor growth wafers onto the isolating target wafers. In the present research, graphene was transferred from the chemical vapor deposited 200 mm Germanium/Silicon (Ge/Si) wafers onto isolating (SiO2/Si and Si3N4/Si) wafers by electrochemical delamination procedure, employing poly(methylmethacrylate) as an intermediate support layer. In order to influence the adhesion properties of graphene, the wettability properties of the target substrates were investigated in this study. To increase the adhesion of the graphene on the isolating surfaces, they were pre-treated with oxygen plasma prior the transfer process of graphene. The wetting contact angle measurements revealed the increase of the hydrophilicity after surface interaction with oxygen plasma, leading to improved adhesion of the graphene on 200 mm target wafers and possible proof-of-concept development of graphene-based devices in standard Si technologies.

The influence of pulse-plasma treatment on the phase composition and hardness of Fe-TiB2-CrB2 coatings

This work are presented the research results of pulse plasma treatment influence on the phase composition, hardness, roughness and element composition of coatings on the bases of Fe-TiB2-CrB2. The Fe-TiB2-CrB2 coating was deposited by detonation method. The following pulse-plasma treatment was used to modify the structure and properties of the surface layers of the sprayed coating. The results of mechanical experiments showed that the hardness of Fe-TiB2-CrB2 coating increased after the treatment. On the basis of the X-ray analysis, it has been established that the increase of coating hardness is connected with phase transformations in a surface layer, in particular, with formation of oxide phases and increase of carbide particles quantity.

Influence of a plasma-treated nutrient solution containing 2,4-dichlorobenzoic acid on the growth of cucumber in a hydroponic system

Allelochemicals are organic compounds exuded from the roots of plants, which have autotoxic effects on plant growth. In this study, the decomposition of 2,4-dichlorobenzoic acid (DCBA), an allelochemical of cucumber, by plasma generated in an air bubble in solution is examined, and the influence of plasma treatment of the solution on cucumber growth in a hydroponics system is investigated. Air gas is injected into water through a vertically positioned glass tube, into which a high-voltage wire electrode is placed to generate plasma. The concentration of DCBA decreases and the concentration of chloride ion produced by the dichlorination of DCBA increases with increasing discharge treatment time. Consequently, most DCBA has decomposed after 24 h of treatment. The discharge-treated solution is used as a nutrient solution for cultivating cucumber plants in a rockwool hydroponic system. The results show that the growth of most plants is inhibited by adding DCBA, as well as by the decrease in pH during discharge treatment; in contrast, plants subjected to discharge treatment with pH adjustment grow healthily.

Development and Investigation of PEDOT:PSS Composition Coated Fabrics Intended for Microwave Shielding and Absorption.

This study presents the investigation of the electromagnetic properties and resistance performance of electrically conductive fabrics coated with composition containing the conjugated polymer system poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT:PSS). The developed fabrics were intended for electromagnetic radiation (EMR) shielding in microwave range and for absorbing microwaves in radar operating range, so as to act as radar absorbing materials (RAM). The measurements of reflection and transmission of the developed fabrics were performed in a frequency range of 2–18 GHz, which covers the defined frequencies relevant to the application. Four types of fabrics with different fiber composition (polyamide; polyamide/cotton; wool and para-aramid/viscose) were selected and coated with conductive paste using screen printing method. It was found that EMR shielding effectiveness (SE) as well as absorption properties depend not only the amount of conductive paste topped on the fabric, but also resides in the construction parameters of fabrics. Depending on such fabric structural parameters as density, mass per unit area, type of weave, a layer of shield (or coating) just sticks on the fabric surface or penetrates into fabric, changing the shield thickness and herewith turning SE results. Meanwhile, the fiber composition of fabrics influences mostly bonding between fibers and polymer coating. To improve the resistance performance of the developed samples, a conventional textile surface modification technique, atmospheric plasma treatment, was applied. Initially, before plasma treatment and after treatment the fabrics were evaluated regarding an aqueous liquid repellency test, measuring the contact angles for the water solvent. The influence of plasma treatment on resistance performance of coated fabrics was evaluated by subjecting the plasma treated samples and untreated samples to abrasion in the Martindale abrasion apparatus and to multiplex washing cycles. These investigations revealed that applied plasma treatment visibly improved abrasion resistance as a result of better adhesion of the coating. However, washing resistance increased not so considerably.