Study on the Influence of Nitrogen Plasma on Dyeing Properties of Rex Rabbit Fibers

The surface of rex rabbit fibers is hydrophobic in nature because of the presence of the hard cuticle on its surface, and this hydrophobicity may give rise to many problems in the dyeing and finishing processes. In order to improve its dyeability and decrease dye pollution in sewage discharge, nitrogen plasma was used to modify rabbit fibers and after that the modified fibers were dyed with the anionic dyestuffs (C.I. number 16185). The effects of nitrogen plasma on the dyeing properties and the dyeing behavior for the rex rabbit fibers were studied, the related parameters including the treatment time and discharge power were optimized. Surface morphology and roughness of rex rabbit fibers were characterized by scanning electron microscope and atomic force microscopy. XPS and FTIR-ATR were further performed to determine the surface chemical compositions of rex rabbit fibers. The physical properties of rex rabbit fibers were characterized by tensile strength tests. The results show that nitrogen plasma treatment can remove surface scales on the rex rabbit fibers and introduce more active groups such as hydroxyl (–OH), carbonyl (–C=O), and amino (–NH₂) on the surface of the fibers, which makes rex rabbit fibers have better dyeability, and effectively improves dyeing rate and dye fixation rate.     

Study of the wettability properties of polypropylene nonwoven mats by low‐pressure oxygen plasma treatment

Surface modification by plasma treatment is widely used for textiles and polymeric materials. Plasma processes are environmentally friendly and reduce chemicals and energy consumption. This study reports the effect of cold, low‐pressure oxygen plasma on the wettability properties of polypropylene (PP) nonwoven mats. The wetting properties were examined using contact angle, surface energy, and diameters of the drop after 20 s of treatment. It was found that plasma treatment had a significant effect on the wettability of PP fibers. The ageing for 90 days had no significant effect on the wettability. It was also shown that the morphology of the fibers was not affected by the plasma treatment. Copyright © 2007 John Wiley & Sons, Ltd.     

Enhancement of wettability in low density polyethylene films using low pressure glow discharge N2 plasma

Low pressure glow discharge nitrogen plasma has been used to improve wettability in a low density polyethylene (LDPE) film for technical applications. The plasma treatment was carried out at a power of 300 W for different exposure times in the 1–20 min range. Wettability changes were analyzed using contact angle measurements. In addition to this, plasma‐treated samples were subjected to an aging process to determine the durability of the plasma treatment. X‐ray photoelectron spectroscopy, atomic force microscopy, and scanning electron microscopy were used for surface characterization. The nitrogen plasma treatment considerably reduced contact angle values thus indicating an increase in surface wettability. The spectroscopic study showed presence of oxygen‐based species on the plasma‐treated samples, which are mainly generated after the plasma treatment as a consequence of air exposure. These polar species contribute to improve surface functionalization, but this is almost lost during aging due to the hydrophobic recovery process. Microscopic studies revealed that also small changes in surface roughness occurred during the plasma treatment but these are very low compared to surface activation. The results confirmed that low pressure nitrogen can be considered as an environmentally efficient process to improve wettability in low density polyethylene films. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2390–2399, 2007     

Surface Modification of Banana Fibers by DBD Plasma Treatment

Banana fibers, an environmentally friendly raw material freely available, were physically modified by atmospheric dielectric barrier discharge (DBD) plasma treatment of different dosages. The influence of the plasma treatment applied on the banana fibers was performed considering the mechanical properties, wettability, chemical composition and surface morphology. These properties were evaluated by tensile tests, static and dynamic contact angle, Fourier transform infrared spectroscopy, energy dispersive spectroscopy, X-ray diffractometry, conductivity and pH of aqueous extract, differential scanning calorimetry and scanning electron microscopy images. We compare untreated and treated fibers with three different DBD plasma dosages. The results of this study showed considerable modifications in banana fibers when these are submitted to plasma treatment.     

聚对苯二甲酸乙二酯的等离子体表面改性研究

阐述了等离子体原理,综述了等离子体对聚对苯二甲酸乙二酯表面改性的研究工作,大量的实验数据表明了这种方法可以成功改善各种性能。等离子体处理后PET材料表面粗糙度增加,并产生化学基团,因此可改善以下各种性能:润湿性、粘接性、染色性、抗静电性,对人体的生物相容性,添加TiO2的杀菌性,PET表面化学镀金属的性能。PET表面的刻蚀作用,导致其重量的减轻,可替代部分碱减量处理。     

Comparison Between Air Filamentary and Helium Glow Dielectric Barrier Discharges for the Polypropylene Surface Treatment

Recently, a glow like dielectric controlled barrier discharge (GDBD) working at atmospheric pressure has been observed. Such a discharge could replace a filamentary dielectric controlled barrier discharge (FDBD) used in corona treatment systems to improve the wettability or the adhesion of polymers. So it is of interest to compare these two types of discharges and their respective effect on a polymer surface. This is the aim of an extensive study we have undertaken. The first step presented here is the comparison of a filamentary discharge in air with a glow discharge in helium. Helium is the most appropriate gas to realize a glow discharge at atmospheric pressure. Air is the usual atmosphere for a corona treatment. The plasma was characterized by emission spectroscopy and current measurements. The surface transformations were indicated by the water contact angle, the leakage current measurement and the X-ray photoelectron spectroscopy. Results show that the helium GDBD is better than air FDBD to increase polypropylene wettability without decreasing the bulk electrical properties below a certain level. Contact angle scattering as well as leakage current measurements confirm that the GDBD clearly results in more reproducible and homogeneous treatment than the FDBD.     

Modification of Polyimide in Barrier Discharge Air-Plasmas: Chemical and Morphological Effects

Chemical and physical modifications of polyimide (PI) surfaces caused by an air plasma have been studied. The plasma-induced surface changes of PI were investigated by using a local dielectric barrier discharge (DBD) in air at atmospheric pressure and room temperature as a function of the plasma exposure time and plasma power, while the excitation frequency was kept constant at about 130 kHz. The first results obtained in this work suggest that DBDs operating in air at atmospheric pressure can be an efficient alternative plasma source for surface treatment of polymers: a short time air plasma treatment of few seconds leads to chemical and physical changes including the rise of wettability, surface oxidation, and enhancement of surface roughness. Therefore, this simple kind of dry surface treatment seems to be an effective, low cost method for production of well-adhering subsequent layers such as metal films, paints, glues, etc. on DBD pretreated polymers.     

Fabrication and study of supercapacitor electrodes based on oxygen plasma functionalized carbon nanotube fibers

Dry-spun Carbon Nanotube(CNT) fibers were surface-modified by atmospheric pressure oxygen plasma functionalization using a well controlled and continuous process. The fibers were characterized by scanning electron microscopy(SEM), Raman spectroscopy, and X-ray Photoelectron Spectroscopy(XPS). It was found from the conducted electrochemical measurements that the functionalized fibers showed a 132.8%increase in specific capacitance compared to non-functionalized fibers. Dye-adsorption test and the obtained Randles-Sevcik plot demonstrated that the oxygen plasma functionalized fibers exhibited increased surface area. It was further established by Brunauer-Emmett-Teller(BET) measurements that the surface area of the CNT fibers was increased from 168.22 m~2/g to 208.01 m~2/g after plasma functionalization. The pore size distribution of the fibers was also altered by this processing. The improved electrochemical data was attributed to enhanced wettability, increased surface area, and the presence of oxygen functional groups, which promoted the capacitance of the fibers. Fiber supercapacitors were fabricated from the oxygen plasma functionalized CNT fiber electrodes using different electrolyte systems. The devices with functionalized electrodes exhibited excellent cyclic stability(93.2% after 4000 cycles), flexibility, bendability, and good energy densities. At 0.5 m A/cm~2, the EMIMBF4 device revealed a specific capacitance, which is 27% and 65% greater than the specific capacitances of devices using EMIMTFSI and H_2 SO_4 electrolytes,respectively. The practiced in this work plasma surface processing can be employed in other applications where fibers, yarns, ribbons, and sheets need to be chemically modified.     

Activation of Spruce Wood Surfaces by Plasma Treatment After Long Terms of Natural Surface Inactivation

Surface inactivation is a phenomenon that causes poor adhesion. A wood surface exposed to contaminants such as dust or atmospheric grime can experience surface inactivation. Inactivation mechanisms can reduce the attractive forces on the wood surface and lead to a decrease in wettability. Plasma treatment has been applied to recover inactivated wood surfaces for better adhesion and bonding. Plasma treatment technology is very simple and the cost is rather low. In addition, this treatment produces no environmental pollution. In this study, low pressure plasma treatment was applied to reactivate the surfaces of spruce wood for glue bonding and to increase wettability after a 9-year period of natural surface inactivation. Changes in contact angles, surface energy, surface colour and bonding strength of inactivated and oxygen plasma treated wood surfaces were studied. Wettability, bonding and other mechanical strength properties of plywood panels increased with the oxygen plasma treatment.     

Surface characteristic of poly(p‐phenylene terephthalamide) fibers with oxygen plasma treatment

Oxygen plasma is widely employed for modification of polymer surfaces. Plasma treatment process is a convenient procedure that is also environmentally friendly. This study reports the effects of oxygen plasma treatment on the surface properties of poly(p‐phenylene terephthalamide) (PPTA) fibers. The surface characteristics before and after oxygen plasma treatment were analyzed by XPS, atomic force microscopy (AFM) and dynamic contact angle analysis (DCAA). It was found that oxygen plasma treatment introduced some new polar groups (O? C?O) on the fiber surface, increased the fiber surface roughness and changed the surface morphologies obviously by plasma etching and oxidative reactions. It is also shown that the fiber surface wettability was improved significantly by oxygen plasma treatment. Copyright © 2008 John Wiley & Sons, Ltd.     

Novel AC and DC Non-Thermal Plasma Sources for Cold Surface Treatment of Polymer Films and Fabrics at Atmospheric Pressure

Novel types of non-thermal plasma sources at atmospheric pressure based on multi-pin DC (direct current) diffusive glow discharge and AC (alternative current) streamer barrier corona have been elaborated and tested successfully for cold surface treatment of polymer films [polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET),] and polyester fabric. Results on physical properties ofdischarges mentioned and output energy characteristics of new plasma sources as well as data on after-treatment changes in wettability of films and fabrics are presented. The main goal of this study was to find out the experimental conditions for gas discharge and surface processing to achieve a remarkable wettability change for a short treatment time.     

On the Use of Atmospheric Pressure Plasma for the Bio-Decontamination of Polymers and Its Impact on Their Chemical and Morphological Surface Properties

Low temperature atmospheric pressure plasma processes can be applied to inactivate micro-organisms on products and devices made from synthetic and natural polymers. This study shows that even a short-time exposure to Ar or Ar/O₂ plasma of an atmospheric pressure plasma jet leads to an inactivation of Bacillus atrophaeus spores with a maximum reduction of 4 orders of magnitude. However, changes in the surface properties of the plasma exposed material have to be considered, too. Therefore, polyethylene and polystyrene are used as exemplary substrate materials to investigate the effect of plasma treatment in more detail. The influence of process parameters, such as type of operating gas or jet-nozzle to substrate distance, is examined. The results show that short-time plasma treatment with Ar and Ar/O₂ affects the surface wettability due to the introduction of polar groups as proofed by X-ray photoelectron spectroscopy. Furthermore, atomic force microscopy images reveal changes in the surface topography. Thus, nanostructures of different heights are observed on the polymeric surface depending on the treatment time and type of process gas.     

Physical and chemical analysis of plasma-treated cotton fabric subjected to wrinkle-resistant finishing

Cotton fabrics were treated with oxygen plasma gas and/or wrinkle-resistant finishing agent with polycarboxylic acid. The results of wicking rate, contact angle and wettability tests revealed that the atmospheric plasma treatment significantly improved hydrophilicity of cotton fiber. Such improvement greatly enhances the effectiveness of post-finishing processes. The study showed that chemical composition of cotton fabric surface changed after plasma and wrinkle-resistant treatment. Chemical composition of surface of treated cotton specimens was evaluated with different characterization methods, namely, FTIR-ATR and EDX. The experimental results are thoroughly discussed.     

Plasma Treatment of Glass Surfaces Using Diffuse Coplanar Surface Barrier Discharge in Ambient Air

We report a study on the treatment of flat glass surfaces by ambient air atmospheric pressure plasma, generated by a dielectric barrier discharge of coplanar arrangement of the electrode system—the diffuse coplanar surface barrier discharge (DCSBD). The plasma treatment of glass was performed in both static and dynamic modes. With respect to wettability of the glass surface, treatment in static mode resulted in non-uniform surface properties, whereas dynamic mode provided a fully uniform treatment. A water contact angle measurement was used to determine the efficiency of plasma treatments in dynamic mode and also to investigate a hydrophobic recovery of plasma treated glass surfaces. The X-ray photoelectron spectroscopy measurements showed a decrease of overall carbon concentrations after plasma treatment. A deconvolution of C1s peak, showed that a short plasma treatment led to decrease of C–C bonds concentration and increases of C–O and O–C=O bond concentrations. An enhancing influence of the glass surface itself on DCSBD diffuse plasma was observed and explained by different discharge onsets and changes in the electric field distribution.     

Effect of cold atmospheric plasma treatment on hydrophilic properties of fluorosilicone rubber

Vulcanized fluorosilicone rubber for aviation was treated by argon and oxygen cold atmospheric plasma (CAP) in order to modify its hydrophilic properties. The sample's chemical composition was analyzed by X‐ray photoelectron spectroscopy (XPS). The static contact angle, surface free energy, and adhesion strength were used to indicate the hydrophilic properties. Additionally, the surface morphologies of the specimens were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results showed that the contact angle declined from 101.5° to 22°, and the surface energy rose from 21.3 to 71.2 mJ/m² after they were treated by argon plasma. Alternatively, the water contact angle decreased to 25.5°, and the surface energy increased to 70.6 mJ/m² after they were treated by oxygen plasma. In addition, the SEM and AFM images of the samples illustrate that the treated surface of fluorosilicone rubber becomes rougher than the non‐treated surface. The concentrations of carbon (C) and fluorine (F) elements of the material' surface decreased and the contents of O element greatly enriched after plasma treatment. Additionally, chemical group C―O and C―OH appeared after the treatment. However, the hydrophilic effect of the plasma treatment is aged after the specimens were stored for 8–12 h. Copyright © 2016 John Wiley & Sons, Ltd.     

Surface modification of low density polyethylene (LDPE) film by low pressure O2 plasma treatment

In this work, low pressure glow discharge O₂ plasma has been used to increase wettability in a LDPE film in order to improve adhesion properties and make it useful for technical applications. Surface energy values have been estimated using contact angle measurements for different exposure times and different test liquids. In addition, plasma-treated samples have been subjected to an aging process to determine the durability of the plasma treatment. Characterization of the surface changes due to the plasma treatment has been carried out by means of Fourier transformed infrared spectroscopy (FTIR) to determine the presence of polar species such as carbonyl, carboxyl and hydroxyl groups. In addition to this, atomic force microscopy (AFM) analysis has been used to evaluate changes in surface morphology and roughness. Furthermore, and considering the semicrystalline nature of the LDPE film, a calorimetric study using differential scanning calorimetry (DSC) has been carried out to determine changes in crystallinity and degradation temperatures induced by the plasma treatment. The results show that low pressure O₂ plasma improves wettability in LDPE films and no significant changes can be observed at longer exposure times. Nevertheless, we can observe that short exposure times to low pressure O₂ plasma promote the formation of some polar species on the exposed surface and longer exposure times cause slight abrasion on LDPE films as observed by the little increase in surface roughness.     

The Role of Dielectric Barrier Discharge Atmosphere and Physics on Polypropylene Surface Treatment

Dielectric barrier discharge (DBD) is the discharge involved in corona treatment, widely used in industry to increase the wettability or the adhesion of polymer films or fibers. Usually DBD's are filamentary discharges but recently a homogeneous glow DBD has been obtained. The aim of this paper is to compare polypropylene surface transformations realized with filamentary and glow DBD in different atmospheres (He, N₂, N₂ + O₂ mixtures) and to determine the relative influence of both the discharge regime and the gas nature, on the polypropylene surface transformations. From wettability and XPS results it is shown that the discharge regime can have a significant effect on the surface transformations, because it changes both the ratio of electrons to gas metastables, and the space distribution of the plasma active species. This last parameter is important at atmospheric pressure because the mean free paths are short (m). These two points explain why in He, polypropylene wettability increase is greater by a glow DBD than by a filamentary DBD. In N₂, no significant effect of the discharge regime is observed because electrons and metastables lead to the same active species throughout the gas bulk. The specificity of a DBD in N₂ atmosphere compared to an atmosphere containing oxygen is that it allows very extensive surface transformations and a greater increase of the polypropylene surface wettability. Indeed, even in low concentration and independently of the discharge regime, when O₂ is present in the plasma gas, it controls the surface chemistry and degradation occurs.     

Surface Modification by Atmospheric Pressure Air Plasma Treatment to Improve Dyeing with Natural Dyes: An Environment Friendly Approach for Leather Processing

The present study describes surface modification of leather using environment friendly atmospheric pressure dielectric barrier discharge (DBD) process to improve dyeing with natural dyes. Leather samples were exposed to dielectric barrier discharge produced in air. DBD plasma treatment changes morphology and chemical composition of the surface of leather samples. The chemical changes at leather surface are confirmed by Fourier transform infrared spectrometer. The morphology and chemical composition of leather surface is studied using scanning electron microscope and X-ray photoelectron spectroscopy. We observed significant improvement in dye uptake properties after air plasma treatment. Different species formed in plasma are identified using optical emission spectroscopy. Untreated and plasma treated samples were dyed with Eco-Garnet Brown, Eco-Hill Brown III, Eco-Turkey Red and Eco-Smoke Grey natural dyes. Dyeing behavior was assessed by spectroscopic measurement and by measuring fastness (wash and rub) properties. This has clearly indicated an increase in color intensity of plasma exposed leather as well as an increase in the dye uptake as compared to the untreated leather. Best results were obtained with Eco-Hill Brown III and Eco-Smoke Grey dyes. The study reveals that atmospheric pressure plasma has potential to become dry and eco-friendly process to modify leather surface to improve dye uptake properties with natural dyes.     

Plasma surface modification of poly (l-lactic acid) and poly (lactic-co-glycolic acid) films for improvement of nerve cells adhesion

Radio frequency (RF) plasma treatment in O₂ was applied to modify the surface of poly (l-lactic acid) (PLLA) and poly (d,l-lactic acid-coglycolic acid) (PLGA) as biodegradable polymers. The surface structure, morphology, wettability and surface chemistry of treated films were characterized by water drop contact angle measurement, scanning electron microscope (SEM), optical invert microscope, differential scanning calorimetry (DSC) and ATIR–FTIR spectroscopy. The cell affinity of the oxygen plasma treated film was evaluated by nervous tissue B65 cell culture in stationary conditions. The results showed that the hydrophilicity increased greatly after O₂ plasma treatment. The results showed that improved cell adhesion was attributed to the combination of surface chemistry and surface wettability during plasma treatment. Cell culture results showed that B65 nervous cell attachment and growth on the plasma treated PLLA was much higher than an unmodified sample and PLGA. Surface hydrophilicity and chemical functional groups with high polar component play an important role in enhancing cell attachment and growth.     

Effect of carbon fiber surface treatments on the flexural strength and tribological properties of short carbon fiber/polyimide composites

Pitch‐based short carbon fibers (CFs) were treated by air oxidation and cryogenic nitrogen, respectively. Thereafter the treated and untreated CFs were incorporated into polyimide (PI) matrix to form composites. The CFs before and after treatment were examined by XPS and SEM.The flexural strength of the specimen was determined in a three‐point test machine and the tribological properties of PI composites sliding against GCr15 steel rings were evaluated on an M‐2000 model ring‐on‐block test rig. The results show that the surface of the treated CFs became rougher. Lots of active groups formed on the CF surface after air oxidation.The treatment can effectively improve the mechanical and tribological properties in their PI composites due to the enhanced fiber‐matrix interfacial bonding. Copyright © 2008 John Wiley & Sons, Ltd.