Effect Of Plasma Modification Research Articles

Effect of plasma modification on UV-curable ink-jet coating on medium-density fiberboard (MDF)

ABSTRACT The UV-curable inkjet coating system on the surface of wood-based substrates consists of the substrate, primer, printing layer, and topcoat layer. To enhance the compatibility at the interface between the UV-curable primer and the inkjet coating on the substrate surface, this study employed air plasma to modify the medium-density fiberboard substrate's primer surface under varying treatment power and speeds. By analyzing the changes in contact angle, chemical composition, and elemental composition of the substrate primer surface under different plasma treatment conditions, theoretical support was provided for the improvement of the bonding between the UV-curable primer and the printing layer. The results show that with a plasma treatment speed of 0.4 m/min and power of 700 W, the contact angle with water on the surface was 20°, and the whiteness value was 80.5 Wb. The C = C bonds on the primer surface break and combine with oxygen elements to form oxygen-containing functional groups or peroxides, increasing the surface polarity and activity of the primer. When the plasma treatment power was 750 W and the speed was 0.8 m/min, the relative concentration of oxygen elements on the UV-curable primer surface increased to 49%, while the carbon element content decreases by 29%.

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.

Enhanced Natural Dyeing and Antibacterial Properties of Cotton by Physical and Chemical Pretreatments

In this study, pomegranate peel extract was used to dye cotton fabrics. Generally, natural dyes have low affinity for cellulosic fibers and therefore need treatment for attachment. Air atmospheric plasma was applied to lower the concentrations of mordants needed and enhance dyeability. The outcomes showed that the residual concentrations of metallic ions decreased when applying the plasma treatment. ATR-FTIR and SEM analysis were performed to evaluate the effect of plasma modification on the surface chemistry and topography of the cellulosic fibers. The traces of metals released from finished fabric were quantified using ICP OES spectrometry. Color fastnesses (wash, rubbing and light) were evaluated to assess the mordanting step effect and the durability of the color. All tested fastnesses were good to very good. The concentrations of metal ions in finished fabrics were 32.4 for Fe, 0.28 for Al, 0.29 for Cr and 1.21 for Cu. Plasma treatment can be considered an efficient strategy to reduce the concentration of toxic metallic mordants.

Molecular simulation of the effect of plasma modification on the microscopic properties of polyimide

Polyimide is often used as the insulating material of the repulsion coil, which needs to withstand the collision of the fast repulsion mechanism in high-speed motion and temperature rise. The polyimide molecular model was established in this study. The external electric field was applied to the model through the semi-empirical method to calculate the total molecular energy, dipole moment, molecular orbital energy, and energy gap of polyimide. It was found that the total molecular energy of plasma-modified polyimide was lower, the energy gap was smaller, and the corresponding molecular properties were more stable. Then, the cell models of ordinary polyimide and plasma-modified polyimide were established by molecular dynamics simulation. The effects of plasma modification on the micro properties of polyimide were studied and compared. The free volume, mean square displacement, cohesive energy density, mechanical properties, and relative dielectric constant of polyimide models with different modified ratios were calculated. The results show that the introduction of polar groups through plasma modification can inhibit the movement of the polyimide molecular chain and improve the thermal stability of the polyimide system. The mechanical properties of polyimide are also improved due to plasma modification, and the elastic modulus is the largest when the modification rate is 20%. At the same time, the relative dielectric constant of polyimide increases with the increase of the modification rate.

Irreversible bonding of PDMS-LiNbO3 heterostructure for microfluidic application by stepwise plasma modification

Owing to the surface acoustic wave produced by lithium niobate (LiNbO3), the combination of LiNbO3 and polydimethylsiloxane (PDMS) was recently applied in microfluidic devices to realize fluid actuation and particle manipulation. However, direct bonding of LiNbO3 substrate to PDMS surface is still a challenge due to the large coefficient of thermal expansion mismatches at the interface. In this work, an efficient method for bonding PDMS-LiNbO3 heterostructure was proposed to improve the bonding strength. Both PDMS and LiNbO3 surfaces were plasma-modified by a stepwise treatment at room temperature. The hydrophilicity, morphology and chemical composition of the modified surface were characterized to analyze the effect of plasma modification. Results showed that plasma modification produced active chemical groups which made the surface extremely hydrophilic, but had no obvious effect on surface morphology. Besides, the bonding strength under different gas composition, flow and time ratio was studied. Compared with oxygen plasma modification, the bonding strength was further increased by oxygen‑nitrogen dual modification, reaching a maximum value of 1396.2 kPa. The bonded devices also showed good seal performance in the leakage test for microfluidic chip. The abundant active chemical groups introduced by dual plasma modification on the surface are the main reason for the improvement of bonding strength. When the modified surfaces contact with each other, these groups at the interface will react with each other, and finally the two interfaces are connected by covalent bonds.

Preparation of Waterproof and Breathable Polyethylene (PE) Film Through One-Step Plasma Treatment

The waterproof and breathable multifunctional films have been widely used in advanced wear protection, medical treatment, monitoring, and the aerospace industry. In this research, we prepared a new class/kind of waterproof and breathable intelligent (WBI) films through plasma surface treatment, which can be applied in the health care field. After air plasma treatments, the structural properties of polyethylene (PE) film were observed by Scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), Thermogravimetry (TG), and Differential scanning calorimetry (DSC). It was found that plasma treatment etches PE fibers due to the sputter etching effect of plasma modification, leading to a crystallinity decrease. In addition, the changes in water contact angle, air permeability, and water vapor transmission rate of PE films were measured to illustrate their waterproof and breathable properties. After plasma treatment, the water contact angle of PE film reduced from 112.67∘ to 45∘, indicating the PE surface converted from hydrophobic into hydrophilic. The air permeability increased to 0.450[Formula: see text]mm/s and the water vapor transmission rate increased to 1419.788[Formula: see text]g/m[Formula: see text], which means the treated PE films are breathable but not permeable to liquid water. The improved performance in waterproof and breathability expands the application of PE film in the pharmaceutical field.

Reactive Magnetron Plasma Modification of Electrospun PLLA Scaffolds with Incorporated Chloramphenicol for Controlled Drug Release.

Surface modification with the plasma of the direct current reactive magnetron sputtering has demonstrated its efficacy as a tool for enhancing the biocompatibility of polymeric electrospun scaffolds. Improvement of the surface wettability of materials with water, as well as the formation of active chemical bonds in the near-surface layers, are the main reasons for the described effect. These surface effects are also known to increase the release rate of drugs incorporated in fibers. Herein, we investigated the effect of plasma modification on the chloramphenicol release from electrospun poly (lactic acid) fibrous scaffolds. Scaffolds with high—50 wt./wt.%—drug content were obtained. It was shown that plasma modification leads to an increase in the drug release rate and drug diffusion coefficient, while not deteriorating surface morphology and mechanical properties of scaffolds. The materials’ antibacterial activity was observed to increase in the first day of the experiment, while remaining on the same level as the unmodified group during the next six days. The proposed technique for modifying the surface of scaffolds will be useful for obtaining drug delivery systems with controlled accelerated release, which can expand the possibilities of local applications of antibiotics and other drugs.

Modification of the Hygroscopic Properties of Textile Materials Containing Polyurethane Threads

The article discusses the influence of the presence of polyurethane (elastomeric) threads in the composition of a textile material on the effect of plasma modification of hygroscopic properties. The objects of the study were textile (knitted) fabrics based on cotton fibers with the addition of Dorlastan threads. The samples were processed in the plasma of a high-frequency capacitive discharge at a reduced pressure, as the plasma-forming gas was used air. Experiments have shown that the water absorption of the samples after plasma treatment is increased by an average of 1.5 times. The presence of Dorlastan thread does not significantly affect the result of the plasma modification, since the samples are completely immersed in water and the elastomeric threads do not limit the water absorption of its cotton component. The degree of capillary rise, on the contrary, depends on the presence of polyurethane threads. In samples made of 100% cotton, the increase occurs up to 190-. According to these samples, polyurethane threads prevent the capillarity of water by about 4 times. Kinetic curves of water absorption are given. The results suggest that other processing treatments are required to render the polyurethane threads hydrophilicity by plasma treatment. This should be considered in the development of plasma methods for treating textile materials, including in terms of matrix for composite materials.

Oxygen plasma modification of carbon fiber rovings for enhanced interaction toward mineral-based impregnation materials and concrete matrices

The insufficient bond strength of carbon fibers (CFs) towards cementitious matrices limits at present their prospective application as CF-reinforcement in construction. In this investigation an oxygen plasma modification process was utilized to tailor the surface properties of CF rovings in achieving higher affinity towards mineral-based aqueous suspensions. A systematic study on various process parameters was performed to outline expedient treatment regimes. X-ray photoelectron spectroscopy, single fiber tensile tests, and Weibull-analysis delivered insights on the effects of plasma modification on the carbon fibers’ properties.Mineral-impregnated carbon fiber (MCF) reinforcement bars were produced and characterized by means of pullout tests. It was found that short plasma treatment time, high oxygen flow rates, low pressure, and long pulse duration improved the shear strengths of the MCF bonds on being extracted from the concrete matrix. Morphological analysis revealed that a higher oxygen concentration enables better wetting behavior towards the mineral matrices and, hence, yields higher bond strength.

Influence of plasma modification on free surface energy of synthetic fibrous materials

The results of experimental studies of the effect of plasma modification in various plasma-forming gases on the acid-alkaline properties and free surface energy of samples of synthetic fibrous materials are presented. The effect of changes in the free surface energy of fiber samples on their adhesion to an epoxy binder in a composite material is studied.

Effect of Plasma Modification of Surface and Sterilization on Optical Characteristics of Polyethylene Terephthalate Track Membranes

Effect of plasma modification of surface and sterilization processes on optical characteristics of a polyethylene terephthalate (PET) track membrane (TM) is studied. The TMs are fabricated with the aid of irradiation of PET using 40Ar+8 ion beam and etching in a 1.5-M solution of NaOH. The TMs are modified using low temperature plasma and sterilized with the aid of autoclave treatment and gamma irradiation. The PET TMs exhibit low transmittance and refractivity due to formation of structural inhomogeneities and polymer crystal structure. The effect of plasma and sterilization leads to a decrease in the TM transmittance owing to an increase in the degree of crystallinity and formation of membrane artifacts.

Study of the effect of plasma modification on the change of fire-resistant properties of textile materials imported by flame retardants

The article studies the effect of plasma modification on the flame retardant properties of blended fabrics. The regime of plasma treatment is revealed at which effective and uniform solution absorption of the flame retardant composition of textile materials is achieved. It was found that the most effective fixing of the flame retardant is carried out on samples that underwent double plasma treatment before and after impregnation with the flame retardant.

Surface activation of polyamide fibers by radio-frequency capacitive plasma for application of functional coatings

The results of experimental researches on the modification of polyamide fibrous materials for technical purposes by low-pressure radio-frequency capacitive discharge plasma are presented. The effect of plasma modification on the wettability of polyamide fibers and their adhesive properties was studied.

Effect of plasma modification of polyethylene on natural fibre composites prepared via rotational moulding

The potential use of plasma modified polyethylene (PPE) as a matrix for natural fibre composite has been studied. Rotational moulding technique was employed for the manufacture of composite. Coconut fibre (coir fibre) was selected as the reinforcement and the effect of chemical treatment on fibre also being studied. In fact, the interfacial interaction between coir fibre and PE was analyzed systematically by creating four different types of interfaces (PE/natural fibre, PE/bleached natural fibre, PPE/natural fibre and PPE/bleached natural fibre). Water absorption, scanning electron microscopy and mechanical measurements were carefully carried out to understand the level of interactions between coir fibre and the polymer matrix. The mechanical properties of the PPE coir fibre composites were compared with unmodified PE coir fibre composites. PPE/bleached coir fibre composite showed lower water absorption due to better fibre/matrix interaction. SEM images revealed that a strong interfacial interaction between natural fibre and polymer matrix is possible with plasma modified PE matrix. Finally, it is very important to add that this is the first attempt to demonstrate that Rotational moulding could be successfully applied to plasma modified PE as the matrix and coir fibre as the reinforcing. This work will open tremendous possibility for the application of Rotational Moulding of natural fiber composites.

Printing of µm structures with nano inks using a novel combination of high‐resolution plasma printing and subsequent rotogravure printing

In this paper, we investigated reel‐to‐reel area‐selective microplasma treatment of polymer films using the plasma printing technique in combination with subsequent rotogravure printing. The aim was to explore whether and how the plasma printing pretreatment could contribute to increase print resolution with conductive nano inks on flexible polymer substrates. Substrate materials tested included films of biaxially oriented polyester and polypropylene. As the plasma process gas, a nonflammable mixture of 97% N2 and 3% H 2 was used. Novel microplasma sources developed during the course of this work achieved satisfactory plasma modification effects for the control of ink‐wetting patterns at process speeds of up to 3 m/min. In the case of biaxially oriented polypropylene (BOPP) film, this value was six times higher than the process speeds using previous microplasma sources. The reproduction accuracy achieved with these process parameters was typically better than 1.5% for structures with widths as low as 10 µm. Organic solvent and water‐based ink systems with silver and PEDOT:PSS as conductive components were tested in the rotogravure process following the area‐selective plasma pretreatment. In the combined plasma printing and gravure printing process, a resolution as good as 50 µm, was achieved using an aqueous PEDOT:PSS‐based ink. Conductive tracks produced on BOPP with this ink also passed the tape test for adhesion.

Plasma modification of construction mortar components, an efficient method of increasing their performance

Introduction. The article considers the enhancement of physical and mechanical parameters of construction mortars used for recovering and repairing of building structures of communication collectors by using low-temperature nonequilibrium plasma. The study vindicated the expediency of treatment of construction mortar raw materials with LTNP to enhance their physical and mechanical parameters. The effect of plasma modification of raw materials on Portland cement phase composition, granulometric composition of the sand and mortar properties are analysed. The influence of multiplicity of silica sand and mixing water plasma treatment on the construction mortar strength is considered.
 Materials and methods. Cement-sand mortars are obtained from Portland cement of the CEM I 32.5N and CEM I 42.5N brands and silica sand with the fineness moduli of Mf = 0.32 and Mf = 0.63 and a separate fraction of less than 0.16 mm. Setting time and strength of the building mortars are defined according to GOST state standards in effect. Granulometric composition of the cement is explored by means of Analysette-22 particle size microanalyser, while ARL Optim’X spectrometer is used for studying phase composition of the cement stone, silica sand and cement-sand mortars.
 Results. It is determined that the plasma treatment of Portland cement reduces the grout normal consistency by 15 to 17 % and decreases its setting time by a factor of 3 to 4. Treatment of mixing water with the nonequilibrium low-temperature plasma removes its hardness, forming additional crystallization nuclei. The plasma-treated mixing water increases the curing rate of cement-sand mortars up to 50 % at the early stages of hardening and up to 30 % on the 28th day of hardening. Using plasma-treated silica sand decreases size of its particles and results in partial transition of the crystalline structure into the amorphous one. This reduces water demand of the sand by 10 to 18 %.
 Conclusions. The expedience of plasma treatment of raw materials to enhance the physical and mechanical properties of mortars is vindicated. Owing to the plasma modification of raw materials, quality and process characteristics of construction mortars are improved. The presented method of the plasma treatment of raw materials used to prepare the construction mortars is characterized with high degree of efficiency and convenience of application.

The influence of surface treatment and activation of thin film composite membranes with plasma discharge and determination of their physicochemical properties

In this paper we have focused on the surface treatment and activation of membranes (73 AC and 82 V) with plasma discharge, and on the determination of their physicochemical properties. The surface morphology, wettability, zeta potential of pristine and plasma-treated membranes were tested and compared. Our study is focused on how plasma treatment may be used to tailor the membrane properties. The reactive plasma with functional groups can actively improve the interfacial properties (OH groups for hydrophilicity, NH2 groups for interaction with CO2) and increase separation efficiency of the membrane process. The surface morphology is also significantly affected in the case of membrane 82 V, and rather globular structures appeared on the surface of the plasma-exposed membrane. This change of morphology is also accompanied by a decrease of surface area difference, for both plasma-treated membranes 73 AC and 82 V. Membrane 82 V is more sensitive to the plasma treatment at both of the tested plasma power levels and exposure times. In all cases, the zeta potential changes due to the presence of polar groups on the surface. Plasma modification effects on wettability of both types of membranes revealed that water contact angles (CAs) of membranes 73 AC modified for short times (20 and 60 s) are lower than CAs of the membranes 82 V modified under the same conditions. X-ray photoelectron spectroscopy demonstrated an increase in atomic oxygen concentration upon plasma treatment, which then gradually decreased as a function of time. When the composite membranes are exposed to water, the active layers of the membranes become dense and the transport no longer follows the Knudsen mechanism. These swollen membranes follow a solution-diffusion mechanism and the membranes are much more selective and less permeable for all the measured gases. The permeability reduction is much stronger for H2 compared to CO2. The selectivity increases a lot, especially for the CO2/CH4 pair, from 0.3 up to 13.

Radio-frequency Induction plasma modification effects of disperse systems based on mineral glass

In the article the possibility of use of high-frequency induction plasma discharge of low pressure as a tool for pre-processing the glass optical elements. Established effects of polishing, improve the adhesion of the glass elements to the polymer binder and the increase of the reflection coefficient.

Comparative of fibroblast and osteoblast cells adhesion on surface modified nanofibrous substrates based on polycaprolactone.

One of the determinant factors for successful bioengineering is to achieve appropriate nano-topography and three-dimensional substrate. In this research, polycaprolactone (PCL) nano-fibrous mat with different roughness modified with O2 plasma was fabricated via electrospinning. The purpose of this study was to evaluate the effect of plasma modification along with surface nano-topography of mats on the quality of human fibroblast (HDFs) and osteoblast cells (OSTs)-substrate interaction. Surface properties were studied using scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle, Fourier-transformation infrared spectroscopy. We evaluated mechanical properties of fabricated mats by tensile test. The viability and proliferation of HDFs and OSTs on the substrates were followed by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT). Mineralization of the substrate was determined by alizarin red staining method and calcium content of OSTs was determined by calcium content kit. Cells morphology was studied by SEM analysis. The results revealed that the plasma-treated electrospun nano-fibrous substrate with higher roughness was an excellent designed substrate. A bioactive topography for stimulating proliferation of HDFs and OSTs is to accelerate the latter’s differentiation time. Therefore, the PCL substrate with high density and major nano-topography were considered as a bio-functional and elegant bio-substrate for tissue regeneration applications.

Stability studies of plasma modification effects of polylactide and polycaprolactone surface layers

The article presents results of research on the stability of oxygen plasma modification effects of polylactide and polycaprolactone surface layers. The modified samples were aged for three, six or nine weeks. The studies were carried out using scanning electron microscopy, goniometry and Fourier transform infrared spectroscopy. Studies have shown that the plasma modification has significant impact on the geometric structure and chemical composition of the surface, wettability and surface energy of tested polymers. The modification effects are not permanent. It has been observed that over time the effects of plasma modification fade. Studies have shown that modifying effect lasts longer in the case of polycaprolactone.