Modification of surface properties of polyamide 6 films with atmospheric pressure plasma

To investigate the effect of the different plasma gases treatment on the surface modification of atmospheric pressure plasma, polyamide 6 films were treated using pure helium (He), He/O₂ and He/CF₄, respectively. Atomic force microscopy (AFM) showed rougher surface, while X-ray photoelectron spectroscopy (XPS) revealed increased oxygen and fluorine contents after the plasma treatments. The plasma treated samples had lower water contact angles and higher T-peel strength than that of the control. The addition of small amount of O₂ or CF₄ to He plasma increases the effectiveness of the plasma treatment in polymer surface modification in terms of surface roughness, surface hydrophilic groups, etching rate, water contact angle and bonding strength.     

Influence of absorbed moisture on desizing of poly(vinyl alcohol) on cotton fabrics during atmospheric pressure plasma jet treatment

This paper studies the influence of moisture absorption of cotton fabrics on the effectiveness of atmospheric pressure plasma jet (APPJ) on desizing of polyvinyl alcohol (PVA). Cotton fabrics with three different moisture regains (MR), namely 1.8%, 7.3%, and 28.4% corresponding to 10%, 65%, and 98% of relative humidity respectively, are treated for 16 s, 32 s, 48 s, and 64 s. X-ray photoelectron spectroscopy analysis indicates that the plasma treated PVA has higher oxygen concentration than the control. Mass loss results show that the fabric with the highest MR has the largest mass loss after 64 s plasma exposure. Solubility measurement reveals that the sample with the lowest MR has the highest desizing efficacy and the percent desizing ratio reaches 96% after 64 s exposure plus a 20 min hot wash, which is shown as clean as the unsized sample through scanning electron microscopy analysis. The yarn tensile strength test results show that APPJ has no negative effect on fabric tensile strength.     

Photoemission study of fluorination atmospheric pressure plasma processes on EPDM: Influence of the carrier and fluorinating gas

Fluorination plasma treatments at atmospheric pressure were used to modify the surface composition of EPDM elastomer. In this study, two different precursors (CF₄ and SF₆) and two carrier gases (He and Ar) were used for the surface modification of EPDM elastomer. The surface modifications were studied by means of X-ray photoelectron spectroscopy. We have observed a strong influence of the gas selection on the extent of the surface modification induced with these treatments. In general terms, the use of CF₄ generates a higher concentration of fluorine in the elastomer surface. On the other hand, the use of He as carrier gas also increases the effectiveness of the modification process. The fluorine uptake varies between 2 and 13%, although the formation of fluorine-containing functional groups was detected when the amount of fluorine on the surface exceeded 7%. After all treatments, an important oxygen uptake was observed, with amounts three or four times higher than the untreated elastomer.     

Influence of He/O2 atmospheric pressure plasma jet treatment on subsequent wet desizing of polyacrylate on PET fabrics

The influence of He/O₂ atmospheric pressure plasma jet (APPJ) treatment on subsequent wet desizing of polyacrylate on PET fabrics was studied in the present paper. Weight loss results indicated that the weight loss increased with an increase of plasma treatment time. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) showed an increased surface roughness after the plasma treatment. SEM also showed that the fiber surfaces were as clean as unsized fibers after 35 s treatment followed by NaHCO₃ desizing. X-ray photoelectron spectroscopy (XPS) analysis indicated that oxygen-based functional groups increased for the plasma treated polyacrylate sized fabrics. The percent desizing ratio (PDR) results showed that more than 99% PDR was achieved after 65 s plasma treatment followed by a 5 min NaHCO₃ desizing. Compared to conventional wet desizing, indicating that plasma treatment could significantly reduce desizing time.     

Helium/oxygen atmospheric pressure plasma jet treatment for hydrophilicity improvement of grey cotton knitted fabric

The influence of atmospheric pressure plasma jet (APPJ) treatment on the hydrophilicity of grey cotton knitted fabric (GCKF) was investigated. For comparison, specimens which had undergone different treatments were tested by contact angle measurement, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), fourier-transform infrared attenuated total reflectance spectroscopy (FTIR-ATR) and X-ray diffraction (XRD). The results imply that helium/oxygen APPJ could improve the hydrophilicity of GCKF by modifying the surface properties. In addition, combining dewaxing processes with He/O₂ APPJ treatment was found to tremendously improve the hydrophilicity of GCKF. The mechanism of this was also confirmed by Ruthenium Red staining which showed most of pectic substances inside the cotton fiber existed beneath the waxy layer and on top of the cellulose microfibril.     

The aging of atmospheric plasma-treated ultrahigh-modulus polyethylene fibers

The aging effects of atmospheric plasma treatments on UHMPE fibers are studied. UHMPE fibers are treated for 0.5 and 1 min with He/O₂/air gas and for 2 and 4 min with He/air gas by atmospheric pressure plasma on a capacitively coupled device at a frequency of 5 kHz. The samples are tested for fiber/epoxy interfacial shear strength at time intervals of 0, 3, 15 and 30 days after initial plasma treatment. Scanning electron microscopy shows micro-cracks on each set of treated fibers, which is not affected by aging over the 30 day study. Interfacial shear strengths (IFSS) for plasma-treated fibers are 2–3 times as high as that of the control. The IFSS for the plasma treated fibers remains constant up to 15 days and then decreases afterwards. XPS Analysis shows a slight increase in atomic concentration of oxygen and nitrogen for each plasma-treated sample. For the He/O₂/air plasma-treated samples, XPS analysis shows an observable increase in C–OH bonds, C=O bonds and COOH bonds, while for the He/air plasma-treated samples, there is a slight increase in C–OH and O=C–O bonds. After 30 days, a decrease in oxygen content for all plasma-treated samples is manifested.     

Temporal gas temperature of atmospheric pressure air plasma

In this paper, temporal gas temperature in plasma was measured by Rayleigh scattering in a passive way since synchronization was difficult due to the randomness of current pulses. The plasma was generated between a 10 mm pin-to-plane gap connected to a H.V DC voltage through a 130 MΩ resistor and a skin sample was placed on a grounded plate. Even the plasma can be touched by a human hand without any feeling of warmth, the peak temperature could be 337 K then decrease to 295 K over 60 μs at 1 mm. Moreover, the applied voltage dramatically affects peak current and the peak temperature. Therefore, the transient “high” temperature cannot be touched and the so-called “cold” plasma might not be “cold”.     

Surface cleaning of metal wire by atmospheric pressure plasma

In this study, the possible application of atmospheric pressure dielectric barrier discharge plasma for the annealing of metallic wire is examined and presented. The main purpose of the current study is to examine the surface cleaning effect for a cylindrical object by atmospheric pressure plasma. The experimental setup consists of a gas tank, plasma reactor, and power supply with control panel. The gas assists in the generation of plasma. Copper wire was used as an experimental cylindrical object. This copper wire was irradiated with the plasma, and the cleaning effect was confirmed. The result showed that it is possible to remove the tarnish which exists on the copper wire surface. The experiment reveals that atmospheric pressure plasma is usable for the surface cleaning of metal wire. However, it is necessary to examine the method for preventing oxidization of the copper wire.     

Modification of hydrophobic acrylic intraocular lens with poly(ethylene glycol) by atmospheric pressure glow discharge: A facile approach

To improve the anterior surface biocompatibility of hydrophobic acrylic intraocular lens (IOL) in a convenient and continuous way, poly(ethylene glycol)s (PEGs) were immobilized by atmospheric pressure glow discharge (APGD) treatment using argon as the discharge gas. The hydrophilicity and chemical changes on the IOL surface were characterized by static water contact angle and X-ray photoelectron spectroscopy to confirm the covalent binding of PEG. The morphology of the IOL surface was observed under field emission scanning electron microscopy and atomic force microscopy. The surface biocompatibility was evaluated by adhesion experiments with platelets, macrophages, and lens epithelial cells (LECs) in vitro. The results revealed that the anterior surface of the PEG-grafted IOL displayed significantly and permanently improved hydrophilicity. Cell repellency was observed, especially in the PEG-modified IOL group, which resisted the attachment of platelets, macrophages and LECs. Moreover, the spread and growth of cells were suppressed, which may be attributed to the steric stabilization force and chain mobility effect of the modified PEG. All of these results indicated that hydrophobic acrylic IOLs can be hydrophilic modified by PEG through APGD treatment in a convenient and continuous manner which will provide advantages for further industrial applications.     

Wettability and sizing property improvement of raw cotton yarns treated with He/O2 atmospheric pressure plasma jet

Raw cotton fiber is water repellent due to the existence of the water repellent cuticle layer. This study is designed to systematically investigate how He/O₂ atmospheric pressure plasma jet (APPJ) treatments influence the wettability and the sizing property of cotton yarns. Water absorption time and adhesion of the sizing agent to the cotton roving are used to evaluate the improvement of wettability and sizing property of the yarn respectively. The water absorption time decreases with the increase of the treatment time and the oxygen flow rate, and the decrease of the jet to substrate distance (JTSD). An optimal water absorption time of 0.8 s is obtained with a treatment time of 20 s, JTSD of 1 mm and O₂ flow rate of 0.2 L/min. Scanning electron microscopy (SEM) shows that the etching effect increases with the decrease of the JTSD and X-ray photoelectron spectroscopy (XPS) presents increased oxygen contents after the plasma treatments. An increase of O-CO bonds while a decrease of C-OH/C-O-C bonds are observed when the JTSD is set at 2 mm. However, a remarkable increase of both C-OH/C-O-C and O-CO bonds are achieved when the JTSD is 1 mm. The roving impregnation test results show a nearly doubled adhesion of sizing and a slightly improved breaking elongation, indicating that the plasma treatment does effectively enhance the bonding strength between the fiber and the sizing.     

The influence of moisture on atmospheric pressure plasma etching of PA6 films

The moisture in the substrate material may have a potential influence on atmospheric pressure plasma treatment. In order to investigate how the existence of moisture affects atmospheric pressure plasma treatment, polyamide 6 (PA6) films were treated by helium, helium/oxygen (O₂) plasmas using atmospheric pressure plasma jet (APPJ) at different moisture regain. The film surfaces were investigated using contact-angle measurements, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) to characterize the surfaces. The exposure of PA6 film surfaces to the plasmas led to the etching process on the surfaces and changes in the topography of the surfaces. It was shown that the etching rate and the surface roughness were higher for the 9.33% moisture regain (relative humidity 100%) group than that of the 1.61% moisture regain (relative humidity 10%) group with the same plasma gas and power.     

Atmospheric pressure plasma treatment of wool fabric structures

Polyaniline-wool (PAN-WF), poly(3,4-ethylenedioxythiophene)-wool (PEDOT-WF), polypyrrole-wool (PPy-WF) fabrics were successfully prepared via atmospheric pressure plasma process. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), Fourier Transform Infrared Spectroscopy (FTIR) and four-probe resistance measurements were used to study the properties of the plasma polymer coated wool fabrics. The effects of the addition of iodine doping on the morphology and electrical properties of the fabrics were examined. The lowest electrical resistance was measured to be 7.7 × 10³ Ω cm for PEDOT-I₂-WF sample after washing with water two times.     

新型大气压微波等离子体炬的仿真研究

设计了一种新型的大气压微波等离子体炬结构。入射主频为2 450 MHz,基于HFSS软件对其进行了仿真研究。在仿真过程中,对该结构的各个参数进行了优化,并得出对场强分布的影响规律。结果表明,探针的使用对腔内场分布有很大影响。根据优化参数对微波等离子体炬进行了仿真模拟,在等离子体发生腔产生了高幅值的电场强度,品质因数达到2×104,可以在大气压下激发等离子体。     

Measurement of optical signals as a plasma propagation in the atmospheric pressure plasma jet columns

The propagation of plasma jets with argon gas is characterized in terms of two factors, the effect of electric field distribution along the tube and the effect of voltage polarity, from the observed results of optical signals along the entire column of plasma. The optical signal of plasma propagates from the high electric-field region of high-voltage electrode toward the low field region of the open air-space, regardless of the polarity of the voltage. The optical intensity and the propagation velocity are higher for the positive voltage than for the negative voltage. Moreover, the length of plasma plume exited from the end of the glass tube into the open air is shorter for the negative voltage. When the optical intensity is strong enough, a secondary peak signal follows the primary peak. In the plasma column on the inside of the glass tube, the optical intensity and the propagation velocity depend on the strength of the electric field; they are both high at the high-field region of voltage terminal and decay toward the end of the tube. The velocity is as fast as 10⁴ m/s at the high-field region and slows down to 10³ m/s at the low-field region of the glass-tube end. However, the plasma accelerates drastically to be (10⁴–10⁵) m/s after exiting the glass tube toward open air, even though the electric field is a quite low and thus the optical signal decays low before fading out. The experimental observations present in this report are explained with the propagation of the plasma diffusion waves.     

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通过测量大气压介质阻挡放电等离子体辐射信号,建立偶极子辐射模型,利用快速傅立叶变换,计算了大气压介质阻挡放电等离子体中离子速度分布。计算结果表明,速度分布偏离麦克斯韦分布,并且随着放电过程的进行,离子速度及相对离子数进行有规律的变化。     

Small size plasma tools for material processing at atmospheric pressure

A small size radiofrequency plasma jet source able to produce cold plasma jets at atmospheric pressure is presented. The surface modification of polyethylene terephtalate, polyethylene and polytetrafluorethylene foils is performed by using a scanning procedure. The contact angle measurements reveal that the treatment leads to hydrophilicity increase. The roughening of surface, specific to each material is noticed. A significant improvement of adhesion is obtained as result of atmospheric plasma treatments.     

Surface physical-morphological and chemical changes leading to performance enhancement of atmospheric pressure plasma treated polyester fabrics for inkjet printing

Without any preprocessing, polyester fabric has lower ability to hold on water due to the smooth morphology and chemistry property of polyester fibers. Therefore, patterns directly printed with pigment inks have poor color yields and easily bleed. In this paper, atmospheric pressure plasma was used to pretreat polyester fabric in order to provide an active surface for the inkjet printing. The results showed that surface-modified polyester fabrics could obtain the effects of features with enhanced color yields and excellent pattern sharpness. SEM images indicated that the rough surface of plasma treated fibers could provide more capacities for the fabric to capture inks and also facilitate the penetration of colorant particles into the polyester fabric. XPS analysis revealed that air + 50%Ar plasma introduced more oxygen-containing groups onto the fabric surface than air plasma. Although AFM images indicated that etching effects generated by air plasma treatments were more evident, the air/Ar plasma treated sample has higher K/S value and better color performance. These studies have also shown that the chemical modification of plasma appears to be relatively more significant for improving the effect of inkjet printing.     

大气压介质阻挡射流放电离子速度分布的测量

通过测量大气压介质阻挡放电等离子体辐射信号,建立偶极子辐射模型,利用快速傅立叶变换,计算了大气压介质阻挡放电等离子体中离子速度分布。计算结果表明,速度分布偏离麦克斯韦分布,并且随着放电过程的进行,离子速度及相对离子数进行有规律的变化。     

纳秒脉冲空气辉光放电等离子体及应用

采用基于半导体断路开关的纳秒脉冲高压电源,在两个金属电极之间产生放电区间为1 600 mm×100 mm×25 mm的常压辉光空气等离子体。等离子体发生器采用负高压针电极阵列与平板阳极结构,针电极的直径为1 mm,长度为20 mm,针电极之间的间隔为20 mm,针电极与平板零电位之间的距离为25 mm,在每个负高压针电极末端周围同时形成圆锥形辉光放电,在平板地电极则形成大面积辉光放电。采用电压探针测量了该新型等离子体的放电特性,结果表明：放电脉冲的上升时间为26 ns,最高脉冲输出峰值电压为27 kV;利用该辉光等离子体对幅宽为1 000 mm聚四氟乙烯薄膜进行了表面改性处理,处理后其表面接触角由原来的124°降到69°,亲水性能大为提高。