Plasma-treated Fibers Research Articles

An analysis of ramie fiber (Boehmeria nivea L. Gaud) treated with low temperature plasma using a mathematical model

This research aims to characterize low-temperature plasma-treated ramie fibers (Boehmeria nivea L. Gaud), create a mathematical model, and analyze them using image processing. The effects of low-temperature plasma treatment on ramie fibers were investigated using 30 kV output powers, 4-min treatment times, and a 4 cm electrode distance. SEM and FT-IR spectroscopy were used to investigate various aspects of the ramie fiber’s chemical properties and surface topography. This study used a statistical approach to analyze the SEM images. The statistical analysis was used to investigate the surface roughness using the SEM images. FT-IR analysis discovered that fibers that were exposed for four minutes differed from untreated fibers. According to the findings, plasma treatment caused: (1) ramie fiber became more hydrophilic, as indicated by the presence of hydrophilic functional groups such as hydroxyl (O–H), carboxyl (O–C), and carbonyl (C=O) in FT-IR with a deeper T%, (2) ramie fiber mass reduction was accompanied by an increase in surface roughness via SEM testing and image processing, and (3) plasma-treated fiber had a coefficient of mass variation (CV) of 0.7211 higher than untreated fiber. The novelty of this study is the use of image processing in SEM to observe surface roughness and its relationship to the chemical structure of ramie fibers observed with FT-IR. Another novelty of this research is the mathematical model of the interaction of plasma species with the ramie fibers on the plane electrode for the first time.

Improvement of tensile strength and toughness in aramid/epoxy composites by sequential air plasma and (3-glycidyloxypropyl) trimethoxysilane treatments

This work explores sequential surface treatments involving atmospheric-air plasma and (3-glycidyloxypropyl) trimethoxysilane (GLYMO) to enhance the tensile properties of aramid/epoxy composites. To prove the technical advantages of this approach, aramid fibers received individual (atmospheric-air plasma or GLYMO) or sequential (plasma followed by GLYMO, and vice versa) surface treatments. Single fiber tensile tests (SFT) and X-ray photoelectron spectroscopy (XPS) were employed to characterize changes in aramid fibers upon the surface modifications. SFT revealed that none of the surface treatments compromised their tensile strength (σ max ). Applying GLYMO, whether individually or in sequence (GLYMO followed by plasma and plasma followed by GLYMO), led to a significant enhancement in the fibers’ elastic modulus (E). Composites with plasma-treated fibers displayed a 5% increase in E and an 8.5% increase in σ max , with no changes in toughness. However, the most notable improvements were achieved through sequential plasma followed by GLYMO treatments, resulting in a ~ 10% increase in σ max and a remarkable ~ 40% improvement in toughness. Plasma introduces oxygen-containing groups to the fiber surface, facilitating GLYMO grafting. Subsequent crosslinking of GLYMO with the epoxy resin strengthens the fiber-matrix interface. This sequential surface modification offers an alternative pathway for fabricating composites with superior toughness and σ max .

Effects of plasma treatment on biodegradation of natural and synthetic fibers

This study investigates the application of plasma treatment as a means to enhance biodegradation and modify the structural characteristics of fibrous composites. The methodological component of the study includes the selection of the research object; production of composites; low-temperature plasma treatment, and treatment of biodegradability and mechanical strength of samples. The strengthening of fibers with cellulose leads to a significant improvement in mechanical strength. Such an indicator as mechanical strength increases from 18 to 21 MPa. Treatment of natural fibers with low-temperature plasma led to an increase in mechanical strength from 18 to 25 MPa. Treating reinforced fibers with low-temperature plasma currently results in an even greater enhancement in mechanical strength, increasing from 18 to 29 MPa.The electron microscopy of samples reveals some differences in cell wall microfibrils between plasma-treated and non-treated samples. The non-treated fibres are found to have chips and voids. Meantime, the plasma-treated fibres show structural changes in certain regions which resemble wood charring. Through a comprehensive analysis, this research underscores the substantial impact of plasma treatment on the degradation kinetics and morphological features of cellulose-based composites. The results reveal distinct alterations in the composition and behavior of plasma-treated fibres, signifying a shift towards enhanced biodegradability. The natural fibres examined in this study contained 28–30% lignin, whereas the composites exhibited a lower lignin content of 21–23%. These findings corroborate the inference that plasma treatment induces significant changes in fibre structure, accelerating the biodegradation process by 7 days.

Gentamicin Release Study in Uniaxial and Coaxial Polyhydroxybutyrate-Polyethylene Glycol-Gentamicin Microfibers Treated with Atmospheric Plasma.

The skin is the largest organ and one of the most important in the human body, and is constantly exposed to pathogenic microorganisms that cause infections; then, pharmacological administration is required. One of the basic medical methods for treating chronic wounds is to use topical dressings with characteristics that promote wound healing. Fiber-based dressings mimic the local dermal extracellular matrix (ECM), maintaining an ideal wound-healing climate. This work proposes electrospun PHB/PEG polymeric microfibers as dressings for administering the antibiotic gentamicin directed at skin infections. PHB-PEG/gentamicin fibers were characterized before and after plasma treatment by Raman spectroscopy, FTIR, and XRD. SEM was used to evaluate fiber morphology and yarn size. The plasma treatment improved the hydrophilicity of the PHB/PEG/gentamicin fibers. The release of gentamicin in the plasma-treated fibers was more sustained over time than in the untreated ones.

Interfacial Morphology between Ramie Fibers and Phenolic Resins: Effects of Plasma Treatment and Cure Cycle

Natural fiber–reinforced polymer composites offer many advantages over conventional composite materials, such as availability, low cost, inexpensive, lightweight, and high specific mechanical properties. However, the applications of these materials are still limited due to the challenges in achieving a good interface between the fibers and matrix. This is highly influenced by the fiber surface characteristics and the polymer matrix properties. Therefore, in this study, the surface characteristics of ramie fibers were modified using low-pressure plasma treatment in order to improve their interface to the phenolic resin. Furthermore, the effects of using two different curing cycles (acid cure and thermal cure) on the properties of short ramie fiber-phenolic composites were also investigated. A new method for making mats of random short ramie fibers was developed and used for the fabrication of composites containing plasma-treated fibers. The flexural properties of all composites were tested and the obtained fracture surfaces were investigated using LV-SEM. The results indicate that both plasma treatment and cure cycle conditions influence the fiber–matrix interface and consequently the flexural properties of the composites.

Electrical and mechanical properties of high-strength strain-hardening cementitious composites containing silvered polyethylene fibers

To develop multifunctional fibers for high-strength strain-hardening cementitious composites (HS-SHCC), a silver-plating technique that incorporated fibers with various pre-treatment methods using dopamine and plasma was adopted for polyethylene (PE) fibers. The effect of this plating technique on the mechanical and electrical properties of HS-SHCC was evaluated. For this, the HS-SHCC mixture with a high compressive strength of 84.1 MPa and tensile strength and strain capacity of 12.7 MPa and 8.27% was first developed. Dopamine-activated, silvered PE fiber was most effective on electroless silver plating and decreased bulk resistance of HS-SHCC by approximately 15%, potentially applicable to pavement deicing, self-sensing, electromagnetic interference shielding, etc. The PE fiber was not directly coated by the silver plating without pre-treatment, and the plasma-treated fiber provided an intermediate silver coating efficiency. The silver nanoparticles deposited on the surface of the PE fibers minimally affected the compressive strength of HS-SHCC in the range of −9% to +3% but deteriorated the tensile performance in general. The mixtures with plasma or hybrid treated silvered PE fibers provided similar tensile strengths of approximately 12 MPa to the control mixture. The silvered PE fiber with dopamine pre-treatment resulted in approximately 12% and 24% lower tensile strength and strain capacity (approximately 11.2 MPa and 6.28%, respectively) compared with the plain PE fiber; however, these tensile properties are still sufficiently outstanding, relative to other HS-SHCC types available.

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.

Effect of plasma sizing on basalt fibers adhesion with wood-working resins

Basalt fabric with manufacturer-made silane sizing was additionally treated by propane-butane enriched atmospheric pressure nitrogen plasma for 15 and 30 s. The wetting improvement of treated fabric was demonstrated by faster soaking of K2CO3 solution. FTIR and XPS analyses confirmed the presence of new nitrogen-containing chemical groups. The impact on adhesion was investigated via a shear strength test of basalt fabric inlay between two beech wooden boards. A short 15 s long treatment led to almost 50% increase in melamine-urea formaldehyde (MUF), polyvinyl acetate (PVAC) and epoxy resin bond strength. Phenol-resorcinol formaldehyde (PRF) needed longer treatment to achieve a bond strength of 11.2 MPa. Only the polyurethane (PUR) showed reduced adhesion to plasma-treated fibers. However, from all tested resins, PUR exhibited the highest bond strength (15.7 MPa) with untreated basalt fabric. The SEM of tested specimens confirmed the changes in the mechanical adherence of resins to plasma treated fibers. Based on these results, PRF and PUR seem to be the most suitable polymers for basalt fibers reinforcement of structural wood-based materials.

Generation of a Highly Efficient Electrode for Ethanol Oxidation by Simply Electrodepositing Palladium on the Oxygen Plasma-Treated Carbon Fiber Paper

In this study, a highly efficient carbon-supported Pd catalyst for the direct ethanol fuel cell was developed by electrodepositing nanostructured Pd on oxygen plasma-treated carbon fiber paper (Pd/pCFP). The oxygen plasma treatment has been shown to effectively remove the surface organic contaminants and add oxygen species onto the CFP to facilitate the deposition of nano-structured Pd on the surface of carbon fibers. Under the optimized and controllable electrodeposition method, nanostructured Pd of ~10 nm can be easily and evenly deposited onto the CFP. The prepared Pd/pCFP electrode exhibited an extraordinarily high electrocatalytic activity towards ethanol oxidation, with a current density of 222.8 mA mg−1 Pd. Interestingly, the electrode also exhibited a high tolerance to poisoning species and long-term stability, with a high ratio of the forward anodic peak current density to the backward anodic peak current density. These results suggest that the Pd/pCFP catalyst may be a promising anodic material for the development of highly efficient direct alcohol fuel cells.

Influence of plasma treatment on the physical and chemical properties of sisal fibers and environmental application in adsorption of methylene blue

The sisal fiber (agave sisalana) is a natural material that presents interesting physical and chemical properties, such as, good adsorption capacity, biodegradability and possibility to be used in composites. Improving these properties is of great importance since sisal fiber may be used in various technological applications. The aim of this work was to study the influence of surface treatment on sisal fibers properties and its effect over methylene blue (MB) adsorption using kinetics models and isotherms studies. The treatment herein used was reactive microwave-assisted cold plasma using mixtures of Ar and CO2, which appears as an alternative to traditional chemical treatments. The adsorption kinetics studies were conducted in order to elucidate the behavior between adsorbent and adsorbate. For this purpose, two isotherm models were used, (i) Redlich-Peterson and (ii) Langmuir. The results show that the plasma treatment promoted an increase in fiber surface roughness, a slight and insignificant decrease in the fiber crystallinity index as well as the breaking and removal of hydroxyl groups with consequent modification of the lignocellulosic material’s original structure. The surface modification of sisal fibers by using cold plasma method promoted greater removal of the MB molecules reaching a 96 %. Kinetic and isotherm studies indicated that the adsorption mechanisms were favorable for both fibers and probably occurred in heterogeneous sites for both pristine and plasma-treated fibers. It was observed that the plasma treatment did not cause the loss of the original properties of the fibers and plays a fundamental role in increasing the adsorption, being indicated for wastewater pollutant removal processes at a low production cost as an alternative to the chemical process currently used.

Composites from recycled polyethylene and plasma treated kapok fibers

In this study, composites from recycled polyethylene and kapok fibers were prepared with fiber contents of 1, 5 and 10 wt%. Cold plasma treatment was applied to the fibers in an attempt to improve fiber/matrix adhesion. The characterization of plasma treated fibers indicated modification in chemical composition and water and oil uptake, as compared to untreated fibers. The addition of plasma treated fibers to the polymer promoted a reduction in the steady-state torque during mixing. In addition, the thermal conductivity of composites was reduced as the amount of fibers increased. Dynamic mechanical thermal analyses of composites with plasma-treated fibers indicated an increase in storage moduli, as well as an increase in glass transition temperature as compared to the pure polymer. Images of fractured surfaces show fibers well connected to the matrix suggesting good fiber/matrix adhesion. Thus, cold plasma is demonstrated as a viable non-polluting alternative to activate cellulosic fibers and improve fiber/matrix interface in polymer composites.

Fluorination of sized glass fibres for decreased wetting by atmospheric pressure plasma treatment in He/CF4

ABSTRACTSized glass fibre bundles were treated using atmospheric pressure plasma in a helium/tetrafluoromethane gas mixture. X-ray photoelectron spectroscopy showed that fluorine was introduced onto the sizing surface. A new analysis method (dynamic micro-wetting) to determine the wetting rate of the plasma-treated fibre bundles is presented. The dynamic micro-wetting test using glycerol as a test liquid showed a reduced wetting rate after plasma treatment. It is demonstrated that dynamic micro-wetting is a useful tool for the characterization of fibre bundle wetting.

Synergetic effect of electrospun PCL fiber size, orientation and plasma-modified surface chemistry on stem cell behavior

Electrospun polymeric meshes have revolutionized the evolving tissue engineering field for their extracellular matrix mimicry. However, besides the fibrous architecture, cell-material interactions are also critically and synergistically influenced by specific surface chemical and topographical features, such as fiber size and fiber orientation. To examine these effects in detail, random polycaprolactone (PCL) fibers with average diameters of 232, 500 and 1272 nm and highly aligned fibers with diameters of 225, 482 and 1173 nm are electrospun in this work. Surface biofunctionalization is then achieved by plasma-treating the fibers using argon at medium pressure. Results reveal a significantly enhanced wettability on plasma-treated fibers due to the incorporation of oxygen-containing functionalities on their surface. A treatment time of 15 s is shown to preserve the scale and morphology of all fiber conditions. However, an extended plasma exposure starts damaging the fibers with a growing risk of drastic alterations on thicker and random fibers compared to thinner and aligned fibers. These diverse responses stem from the distinct molecular chain arrangement and crystallinity of different fiber sizes and orientations. The fibers bioresponsive properties are also profoundly investigated in this study by seeding and evaluating adipose-derived stem cells (ADSCs) performance. Plasma treatment strikingly enhances the cell metabolic activity, adhesion, proliferation and cytoplasmic remodeling on all samples. Cells adhere multi-directionally on random fibers with a gradual change from dilated and more circular to a stretched out and more elongated shape on increasing diameters. In contrast, ADSCs overextend in a bipolar and aligned fashion on aligned fibers with a tendency to attach on fewer fibers with increasing fiber diameter. A critical distinction is the cell infiltration in-between the pores of the thickest fibers. Overall, plasma-treated fibers are very promising substrates for multiple tissue engineering applications. Since the desired ADSCs behavior observed on distinct fiber size and orientation strongly depends on a specific end-application, this work constitutes a picture-perfect reference paving the way towards the optimization of the previous generation of scaffolds.

Effect of cold plasma treatment on recycled polyethylene/kapok composites interface adhesion

ABSTRACTComposites from recycled polyethylene and kapok fibers were prepared using untreated and plasma-treated fibers. Flow properties, mechanical properties and fracture morphology were analyzed in order to evaluate the effects of cold plasma treatment on kapok fibers to improve interfacial bonding between fibers and matrix. Melt flow rate (MFR) measurements indicated a reduction in flow rate of the polymer with the addition of kapok fibers. Storage modulus increased with fiber addition and this effect was more significant when plasma-treated fibers were used. Tanδ obtained from viscoelastic characterization also suggested improvements in fiber/matrix interface as a result of plasma treatment. Addition of kapok fibers to polyethylene produced a reduction in onset decomposition temperature determined from thermogravimetry curve. However, the decrease in temperature observed does not limit composite processing. Furthermore, the degree of crystallinity of polyethylene increased with the addition of untreated fibers and reduced when plasma treated fibers were added. Morphological analysis of failure surface by Field Emission Gun Scanning Electron Microscopy (FEGSEM) suggest that fiber/matrix adhesion was clearly improved when plasma treated fibers were used. Thus, the oxygen cold plasma treatment proved to be an effective non-polluting approach to enhance matrix/fiber adhesion in polyethylene/kapok fiber composites, as opposed to chemical treatments.

Investigation of the effects of plasma-treated chitosan electrospun fibers onto biofilm formation

This work describes the synthesis and characterization of new plasma-treated chitosan derivatives for the prevention of the biofilm formation of Pseudomonas aeruginosa PA01 (P. aeruginosa PA01) on the fiber surfaces of chitosan (Ch) samples.Plasma-treated samples of chitosan-thiophene (Ch-PTh), chitosan-furan (Ch-PFu) and chitosan-3,4-ethylenedioxythiophene (Ch-PEDOT) were prepared with RF rotating plasma. Characterization and investigation of the properties of plasma-treated chitosan samples were carried out using Fourier transform infrared spectroscopy (FTIR), photoluminescence spectroscopy (PL) and X-ray photoelectron spectroscopy (XPS) techniques. XPS data confirmed that a surface layer of the plasma-treated chitosan was enriched with thiophene, furan and 3,4-ethylenedioxythiophene. The surface morphology and diameter of the plasma-treated chitosan derivative fibers were analyzed using scanning electron microscopy (SEM).Plasma-treated chitosan derivative fibers were obtained using electrospinning-quartz crystal microbalance (QCM) methods. Finally, QCM was used to investigate initial adhesion and subsequent biofilm formation of P. aeruginosa PA01 on electrode surfaces coated with the plasma-treated fibers. Biofilm formation of P. aeruginosa PA01 on electrode surface coated with Ch-PFu fiber was significantly inhibited as compared to the others.

Hydrophobic surface modification of ramie fibers by plasma-induced addition polymerization of propylene

The low affinity between hydrophilic cellulose fibers and hydrophobic matrices leads to poor interfacial bonding, reducing the mechanical performances of natural cellulose fiber-reinforced composites. This study illustrates plasma-induced addition polymerization of propylene to create a hydrophobic surface on ramie fibers for enhancing their bonding with polypropylene (PP). Plasma treatment with propane is applied for comparison. The advancing contact angles of the plasma-treated ramie fibers are raised from 66.3° to 106.1° and the interfacial shear strengths with PP are enhanced up to 36.4%, likely resulted from the increase in fiber surface roughness observed under a scanning electron microscope and the introduction of plasma-grafted PP and alkyl groups on fibers surfaces proven by X-ray photoelectron spectroscopy. It is also revealed that plasma treatment with propylene is highly effective in increasing surface carbon content (from 68.3% to 82.4% in 0.5 min) and more efficient than the treatment with propane, though both plasma treatments show substantial modification efficacies to the fiber surfaces. The treatment duration affects surface roughness more than surface chemical composition, and the optimized treatment time is around 1 min. The modification method developed in this research has the potential to be used for surface modification of fibers for many applications.

Surface Treatment of PMIA Fibers with Sub-Atmospheric Pressure Dielectric Barrier Glow Discharge Plasma

Meta-aramid fibers were treated by sub-atmospheric pressure dielectric barrier glow discharge plasma. The effect of plasma treatment time on the fiber surface physical and chemical properties was studied by using surface characterization techniques. Scanning electron microscopy (SEM) was performed to determine the surface morphology changes. FT-IR spectroscopy measurements were performed to investigate the change of chemical structure. Dynamic contact angle analysis (DCAA) was used to examine the changes of the fiber surface wettability. SEM analysis showed that there was obvious crack along the fibers’ axial direction present on the fiber surface, which resulted in the better wetting behavior of the plasma-treated PMIA fiber. FT-IR analysis showed that plasma had little effect on the chemical structure of PMIA fibers. DCAA analysis showed that the wettability of the samples could be improved with the treatment time increasing. In addition, a slight decrease in breaking strength was observed at the treatment time ranging from 60 to 180 s in comparison with the untreated sample.

Effect of cold oxygen plasma treatment on mechanical properties of phenylenebenzobisoxazole fiber-filled cross-linked polyethylene composites

Mechanical strength of phenylenebenzobisoxazole (PBO) fibers and cross-linked polyethylene (XLPE) matrix composites were studied with particular interest on the effects of oxygen cold plasma-treated fibers. PBO fibers were treated in a radio frequency plasma reactor using oxygen for different treatment times to increase the interface adhesion. Tensile tests on PBO fibers showed that plasma treatment caused an increase in average tensile strength compared with untreated fibers. Fracture analysis confirmed the increase in interfacial adhesion due to oxygen plasma treatment.

Study of interaction between nitrogen DBD plasma-treated viscose fibers and divalent ions Ca2+ and Cu2+

Viscose fibers were treated with atmospheric pressure dielectric barrier discharge (DBD) plasma obtained in nitrogen in order to activate the fiber surface prior to sorption of the divalent ions Ca2+ and Cu2+. Methylene blue sorption was used for estimation of carboxyl group formation on the surface after DBD plasma treatment, through the degree of fabric staining (K/S). Sorption of divalent ions was performed from solutions of each individual ion and from solutions of calcium and copper in succession onto untreated and plasma-treated viscose samples. The quantity of sorbed metal was determined from the neutralization and iodometric titration method. Scanning electron microscopy coupled with energy dispersive X-ray analysis was used for fiber morphology and surface characterization before and after plasma treatment, and after metal ions sorption. Experiments revealed copper microparticles formation on the fiber surface when sorption of copper was performed on samples with bonded calcium. Further analysis confirmed that for growth of copper particles, both calcium ions and nitrogen DBD plasma pretreatments are necessary.

Creating cellulose fibres with excellent UV protective properties using moist CF4 plasma and ZnO nanoparticles

Weakly ionised gaseous plasma created in a moist tetrafluoromethane gas at a low pressure with an electrodeless radiofrequency discharge was applied to modify the surface properties of cellulose fibres. The plasma was used to increase the adsorption of zinc oxide (ZnO) nanoparticles such that cellulose fibres with good ultraviolet (UV) protective properties could be created. The UV protection factor (UPF) values of the ZnO-functionalised fibres were determined as a function of the plasma treatment time. The chemical and physical surface properties of the plasma-treated fibres were examined using scanning electron microscopy, X-ray photoelectron spectroscopy, and wettability tests. The quantity of zinc on the fibres was determined using inductively coupled plasma mass spectroscopy. The results indicated that 30 s of plasma treatment resulted in ZnO-functionalised samples with lower UPF values than samples without plasma treatment due to the creation of fluorine-rich functional groups on cellulose fibres and the agglomeration of ZnO nanoparticles. The highest UPF values (50+) were obtained when samples were treated with plasma for 10 s. These high UPF values were a result of the increased adsorption of uniformly distributed ZnO nanoparticles caused by fibres surface functionalization and roughening upon plasma treatment. Furthermore, the mechanical properties of textiles treated with moist CF4 plasma for 10 s were slightly improved.