Surface study of composite photocatalyst based on plasma modified activated carbon fibers with TiO2

Composite photocatalyst was prepared by the nitrogen plasma modification of active carbon fibers (ACF) loaded with TiO₂ using a tetrabutyl titanate hydrolyzing process. The surface morphology was characterized by SEM. The specific surface area and the pore size distribution of ACF were compared by N₂ adsorption before and after modification loaded TiO₂. The surface chemical functional groups and the performance of photocatalyst were investigated by XPS and formaldehyde decomposition respectively. The results show that after carrier surface nitrogen plasma modification, the surface morphology of composite photocatalyst barely changed, the surface area and pore volume decreased slightly, XPS revealed that nitrogen plasma modification could remarkably change the distribution of the oxygen functional groups on the carrier surface and adsorbing oxygen species on the surface of the composite photocatalyst increased. The efficiency of formaldehyde photocatalysis purification was improved by modification.     

Surface modification and characterizations of basalt fibers with non-thermal plasma

Atmospheric-pressure non-thermal plasmas have been increasingly promoted for polymer surface modification. In this paper, atmospheric-pressure plasmas of oxygen, argon, hydrogen and mixture gases of nitrogen and hydrogen were used to surface modification of basalt fibers in order to illuminate their chemical durability, surface active groups and roughness etc. The plasma-induced surface changes on morphologies and active groups were characterized by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The results exhibited a remarkable increase in chemical stability and excellent adhesion, accompanied by extensive etching and by the implantation of both oxygen- and nitrogen-containing polar groups such as NH₂, OH and so forth. Etching of oxygen was mainly a consequence of ion bombardment, yielding low molecular weight and roughness, while surface chemical modifications of mixture of hydrogen and nitrogen were mainly due to the action of neutral species on the plasma-activated basalt fiber surface. The possible formation mechanism of functional groups on the basalt fiber surface was presented.     

Penetration depth of atmospheric pressure plasma surface modification into multiple layers of polyester fabrics

Penetration depth of plasma surface modification of polyester fabrics was investigated. An eight-layer stack of woven polyester fabrics was exposed to a helium/oxygen atmospheric pressure plasma jet. Water-absorption time was used to evaluate surface hydrophilicity on the top and the bottom sides of each fabric layer and water capillary rise height was recorded as a measure of modification effectiveness for each fabric layer. Surface morphology and chemical compositions of each fabric layer in the stack were analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). After atmospheric pressure plasma jet treatment, the top side of the polyester fabric became more hydrophilic. The penetration of plasma surface modification into the fabric layers was deeper for fabrics with larger average pore sizes. It was found that helium/oxygen atmospheric pressure plasma jet was able to penetrate 8 layers of polyester fabrics with pore sizes of 200 μm.     

Nitrogen plasma functionalization of low density polyethylene

Low density polyethylene (LDPE) films have been treated with different nitrogen containing plasmas with the purpose of incorporating nitrogen functional groups on its surface and analyzing the changes experienced in their surface tension. Effects of a dielectric barrier discharge (DBD) at atmospheric pressure and a microwave discharge (MW) at reduced pressure are compared with those obtained by using an atom source supplied with N₂ and mixtures Ar + NH₃ as plasma gas. X-ray photoelectron spectroscopy (XPS) analysis has provided information about the chemical surface changes whereas the surface topography of the treated samples has been examined by atomic force microscopy (AFM). Non-destructive depth profiles of oxygen and carbon have been obtained for the treated and one month aged samples by means of the non-destructive Tougaard's method of XPS background analysis. Generally, an oxygen enrichment of the deeper region of treated LDPE surfaces has been observed. Chemical derivatization of the treated samples has shown that a DBD plasma with a mixture of Ar + NH₃ was the most efficient treatment for nitrogen and amine group functionalization. It is argued that the high concentration of NH* species in this plasma is the most important factor in enhancing the nitrogen functionalization of this polymer. It has been also found that the observed increase in hydrophilicity and surface tension cannot be attributed to the anchored nitrogen functional groups formed on plasma treated LDPE. Differences in the plasma activation behaviour of LDPE and that of other polymers subjected to similar treatments are stressed.     

Effect of acidic surface functional groups on Cr(Ⅵ) removal by activated carbon from aqueous solution

The activated carbon with high surface area was prepared by KOH activation.It was further modified by H2SO4 and HNO3 to introduce more surface functional groups.The pore structure of the activated carbons before and after modification was analyzed based on the nitrogen adsorption isotherms.The morphology of those activated carbons was characterized using scanning electronic microscopy (SEM).The surface functional groups were determined by Fourier transform infrared spectroscopy (FTIR).The quantity of those ...     

Surface modification of a polyester non-woven with a dielectric barrier discharge in air at medium pressure

In this paper, a polyester non-woven is plasma treated with a dielectric barrier discharge (DBD) in air at medium pressure (5.0 kPa) and at different discharge powers. Results show that an increasing power leads to a better plasma treatment of the sample. The barrier discharge is characterized by a voltage and current waveform, by a Lissajous figure and by Lichtenberg figures. The surface properties of the plasma treated samples are examined using X-ray photoelectron microscopy (XPS) and scanning electron microscopy (SEM). XPS analysis reveals that surface oxidation by the formation of oxygen-containing functional groups enhances the surface wettability. SEM analysis shows that the sample is not etched by the used barrier discharge. This is due to the low surface energy density of the DBD used in this paper. Therefore, a DBD in air at medium pressure provides an efficient modification of the chemical surface properties of textiles without destroying the physical structure.     

Surface characterisation of plasma treated flexible substrates for waveguide-on-flex application

This paper reports the physical and chemical effects of argon, nitrogen and oxygen plasma treatments on the surface properties of flexible circuit materials. Both KaptonHN™ and Vecstar™ films selected as optical flexible substrates under plasma irradiation were studied by atomic force microscope (AFM), contact angles, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The etch rate enhancement of the polymeric materials is more pronounced in oxygen plasma than in argon or nitrogen plasma. The increases of surface functional groups (-COOH, -CNOH) of plasma-modified polymer films are correlated with the increased presence of polar component in surface free energy. While the plasma treatment on KaptonHN™ substrates have been widely discussed in literature, the detailed characterisation of both pristine and different plasma surface modified Vecstar™ films is reported and compared for the first time.     

The impact of corona modified fibres’ chemical changes on wool dyeing

The main contribution of the present work was to study the impact of Corona-treated wool fabrics’ induced surface properties on dye-bath exhaustion, in order to optimize different dyeing systems. Firstly, the differing chemical aspects of a woven wool fabric's surface were determined using two dissimilar analytical skills (XPS and polyelectrolyte titration). With the intention to establish the ability of low-temperature plasma treatment to change wool fibre morphology which could have an impact on sorption properties, fabrics were dyed with blue acid and blue metal-complex dyes, and dyeing behaviour were studied by means of on-line VIS spectrophotometry. Finally, dyed samples were colourimetricaly evaluated and colour differences calculated. The results provided evidence that the overall carbon C 1s content was decreased while oxygen and nitrogen atoms were increased when using ionized air for fabric modification. It has also been noted that the amount of positive-charged functional groups in various pH ranges are higher for Corona-treated wool fabric in comparison with the untreated that improves hydrophylicity and dyeing properties.     

Differences between effects of ions in plasma on the edge surface of carbon material and those on the basal surface

We studied the effects of argon (Ar) plasma treatment of different surfaces of pyrolytic graphite (PG), which is an anisotropic material, on the PG surface structure, at various sheath voltages but keeping the other plasma parameters constant. We call a surface parallel to the substrate surface a basal surface, and one orthogonal to the substrate surface an edge surface. The experiment revealed that the Ar plasma treatment induces various effects depending on the carbon structure. The contact angle with water on the PG surfaces was decreased by the Ar plasma treatment. Also, X-ray photoelectron spectroscopy (XPS) analysis of the PG surfaces after the Ar plasma treatment revealed that oxygen-containing functional groups had been introduced onto the PG surfaces. The modification effect was greater for the edge surfaces than for the basal surfaces of the PG. Based on these results, we developed a model of ion effects on the basal and edge surfaces of the carbon surface structure.     

Surface modification mechanism of magnesium oxysulfate whiskers via wet chemical method

Magnesium oxysulfate whisker (MOSW) was produced using magnesite and sulfuric acid as raw materials by hydrothermal method and further modified by taking zinc stearate as modifier via wet chemical method. The influences of the amount of modifier, slurry concentration, modification duration, modification temperature and the stirring rate on the surface modification were investigated. The effects of surface modification in functional groups, morphology and electron binding energies of surface elements of MOSW were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The mechanism of modification was analyzed by studying the microstructure model of the surface of MOSW, which was modified by zinc stearate. The results show that the coordination is generated by the Mg element and O in carboxylic ion of modifier, and the chemical bond could be obtained by modification. Moreover, the surface of MOSW bonds the molecules of zinc stearate, and it becomes rough. Then, the hydrophobicity of MOSW is also improved significantly. In addition, the 1s electron binding energies of Mg and O on the surface of MOSW decrease by 1.2 and 0.2 eV, respectively.     

Modification of polystyrene with a highly reactive cold oxygen plasma

Samples of biaxially oriented polystyrene (PS) were exposed to an extremely non-equilibrium oxygen plasma. The neutral gas kinetic temperature was 70 °C, the electron temperature was about 3 eV, the plasma density was about 2 × 10¹⁵ m^− 3, and the neutral oxygen atom density was 4 × 10²¹ m^− 3. The plasma was created with an electrodeless radiofrequency discharge and the samples were kept at a floating potential. The plasma treatment time was between 1 and 50 s. The samples were characterized by high-resolution X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), microbalance, and water contact-angle (WCA) measurements. The etching rate was found to be relatively independent of the treatment time, at about 9 nm/s. The corresponding probability for oxidation with O atoms was calculated from the known flux of O atoms onto the surface, and was close to 6 × 10^− 4. The AFM did not show any appreciable increase in the surface roughness due to the plasma treatment. Both the XPS and the WCA measurements showed a well-activated surface after just a second of plasma treatment. The rapid functionalization was explained by the huge flux of O atoms onto the sample surface. The tilting of the samples during the XPS characterization made it possible to conclude that the oxygen-containing functional groups were concentrated at the surface of the film, at a depth much smaller than that examined by XPS. The functional groups found using XPS were the standard C-O, O-C-O, C = O, O-C═O as well as -O-CO-O-. The appearance of functional groups with a high degree of oxidation, like carboxyl and carbonate, was attributed to the oxygen's interaction with the aromatic phenyl rings. The ageing results showed that the concentration of the oxygen functional groups did not change much, but the contact angle of the water drop increased moderately during the first day and remained almost unchanged after subsequent ageing.     

等离子体改性1Cr18Ni9Ti不锈钢钝化膜的耐蚀性

等离子体改性１Ｃｒ１８Ｎｉ９Ｔｉ不锈钢钝化膜的耐蚀性雷明凯，袁力江，孔常静，张仲麟（大连理工大学大连１１６０２４）电子回族共振（ＥＣＲ）微波等离子体具有高电子密度和离化率，低放电粒子溅射率及无极放电设计等优点［１－２］，为金属钝化膜的改性提供了有效和...     

Surface modification of high performance PBO fibers using radio frequency argon plasma

The radio frequency argon plasma was applied to improve surface properties of the PBO fiber. The fiber tensile strength was measured, and the surface chemical components, topography and wettability were analyzed by X-ray photoelectron spectroscopy (XPS), atomic force microscopy and dynamic contact angle analysis (DCAA), respectively. Results suggested that over 90% of the fiber tensile strength was reserved after treatment at lower power levels. The surface oxygen atoms increased with a very small extent and the O/C ratio increased from 0.25 to 0.29. The plasma sputtering caused scission of chemical bonds and damage to the surface crystallizing layers, and thus created many active functional groups and roughened surface. However, at high power conditions the more effective ablation and sputtering effects dramatically reduced the tensile strength, surface oxygen contents and roughness. The fiber surface wettability was markedly increased as a result of the functionalization and roughening effects, but the calculated polar and dispersive free energy did not agree well with the measured surface chemical components due to the different effective depths of the surface layers analyzed by DCAA and XPS. The increased roughness was considered to be another reason. The treated fiber exhibited better adhesion with bismaleimide resin, but the maximum interlaminar shear strength of the PBO/bismaleimide composite could not be reproduced by increasing the treatment time at lower power level conditions.     

等离子体浸没离子注入改善45钢的摩擦学性能

采用灯丝放电和射频(RF)辉光放电等离子体浸没离子注入(PⅢ)工艺对45钢表面进行了氮离子注入强化处理。通过X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、显微硬度、针-盘磨损和电化学腐蚀试验等测试手段，分析比较了经灯丝放电PⅢ和RF辉光放电PⅢ改性后试样表面元素的浓度分布、显微硬度、摩擦磨损性能和耐腐蚀性能。结果表明：不同条件下的氮离子注入均能提高45钢表面的显微硬度、耐磨性和抗腐蚀性能；且RF辉光放电PⅢ处理后试样的显微硬度提高了76．8％，摩擦系数下降到0．3，与灯丝放电PⅢ处理后的试样相比，其表面强化效果更加明显。     

Surface modification of cyclic olefin copolymer substrate by oxygen plasma treatment

Cyclic olefin copolymer (COC) substrate surface was modified by plasma treatment under oxygen atmosphere. The surface properties were evaluated by contact angle measurement, atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS). It was found that the surface acquired oxygen containing polar functional groups such as C-O, C = O, which increased in number as the plasma treatment time increased. As revealed by AFM profile, these changes were accompanied by a slightly increase in roughness. The adhesive ability between the coating layer (ITO) and the COC surface can be improved after optimum plasma treating procedure, which can be proofed by the optical microscope observation after boiling test.     

Effect of acidic surface functional groups on Cr（VI） removal by activated carbon from aqueous solution

The activated carbon with high surface area was prepared by KOH activation. It was further modified by H2SO4 and HNO3 to introduce more surface functional groups. The pore structure of the activated carbons before and after modification was analyzed based on the nitrogen ad-sorption isotherms. The morphology of those activated carbons was characterized using scanning electronic microscopy (SEM). The surface functional groups were determined by Fourier transform infrared spectroscopy (FTIR). The quantity of those groups was measured by the Boehm titration method. Cr(Ⅵ) removal by the activated carbons from aqueous solution was investigated at different pH values. The results show that compared with H2SO4, HNO3 destructs the original pore of the activated carbon more seriously and induces more acidic surface functional groups on the activated carbon. The pH value of the solution plays a key role in the Cr(Ⅵ) removal. The ability of reducing Cr(Ⅵ) to Cr(Ⅲ) by the activated carbons is relative to the acidic surface functional groups. At higher pH values, the Cr(Ⅵ) removal ratio is im-proved by increasing the acidic surface functional groups of the activated carbons. At lower pH values, however, the acidic surface functional groups almost have no effect on the Cr(Ⅵ) removal by the activated carbon from aqueous solution.     

STUDY OF MICROSTRUCTURE ON PAN-ACFS PREPARED BY DIFFERENT ACTIVATION METHODS

1. IntroductionPorous solids play an important role in the fields of separation and purification. Ac-tivated carbon fiber (ACF) is a kind of typically ndcroporous carbonaceous adsorbent,which developed from organic precursors either by physical activation or chemical activa-tion. There are many advant8ges for ACFs comparing with conventional activated carbons(AC), including very faSt adsorption/desorption rates. ACFs can be used in the fOrm ofcloth, paPer or felt and so on. Furthermore A…     

碳纤维复合贴片的界面行为研究

采用低温等离子体法对碳纤维进行表面处理,并在微波固化条件下将碳纤维与环氧树脂复合成形,制得碳纤维复合贴片.采用X射线光电子能谱仪对碳纤维表面的元素组成进行了表征,采用扫描电镜和能量散射光谱(EDS)对碳纤维/树脂界面区的形貌和元素分布进行了表征.结果表明:碳纤维经处理后,其表面氨基官能团的含量增大,有利于纤维与树脂的化...     

Arc plasma nitriding of graphite surface towards production of a hard carbon nitride case

Electrode grade graphite substrates were exposed in a nitrogen plasma produced in a pot type 35 kW dc extended arc furnace/reactor operating in non-transferred mode. Different gas (Ar, N₂, H₂) configurations were employed to nitride graphite for 15-20 min in the thermal plasma. Characterization of the plasma-nitrided graphite surface made by XRD revealed the presence of carbon nitride in a mixed form consisting of different phases. The 120-160 μm thick nitrided case exhibited enhanced microhardness values by more than 7 times. XPS studies confirmed the carbon and nitrogen bonding in the nitrided layer/case grown on surface. A comparison of morphologies between the un-nitrided and nitrided graphite surface showed a significant difference in the microstructure. Micro Raman spectra of the nitrided graphite surface showed further evidence of nitrogen incorporation and corroborate the XPS and SEM results. The new compound, carbon nitride, which was recently predicted from theoretical studies, is found to have been formed by the interaction between carbon (graphite) and nitrogen plasma due to a favourable free energy condition available in the high temperature plasma ambient.     

Influence of pore size on penetration of surface modification into woven fabric treated with atmospheric pressure plasma jet

One of the biggest difference between atmospheric pressure plasma jet (APPJ) and other plasma surface treatment is that only one side (top) of substrate is contacted with plasma jet at atmospheric pressure while in other plasmas two sides (top and bottom) of substrate are both contacted with plasma. The modification of the bottom side of woven fabric treated by APPJ is largely dependent on the penetration of active species in plasma jet, which is accordingly affected by plasma parameters and the structure of materials. In order to investigate the influence of pore size on penetration of surface modification into woven fabric treated with APPJ, four kinds of polyester woven fabrics with different pore sizes were used as the model porous medium. Two groups of parallel polyester fibers are respectively and tightly pasted on the top and bottom side of each fabric. Penetration of plasma effects through the pores was detected by changes in contact angle on the bottom side before and after APPJ treatment. It was further demonstrated by changes in surface morphology and chemical composition using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) analyses. The degree of penetration of APPJ surface modification was increased with the increasing pore size. Complete penetration was realized in fabric with pore size larger than 200 μm and nearly no penetration was found in fabric with the pore size smaller than 10 μm. This is attributed to more active species in plasma jet diffusing through the larger pores in fabric. Those species can reach the bottom side without losing their modifying ability during the movement process. Therefore the pore size might be a more important factor affecting penetration of APPJ surface modification into woven fabric.