Effect of Low-Pressure Nitrogen DC Plasma Treatment on the Surface Properties of Biaxially Oriented Polypropylene, Poly (Methyl Methacrylate) and Polyvinyl Chloride Films

In this study, commercial biaxially oriented polypropylene （BOPP）, polyvinyl chlo- ride （PVC） and poly （methyl methacrylate） （PMMA） films were treated with nitrogen plasma over different exposure times in a Pyrex tube surrounded by a DC variable magnetic field. The chemi- cal changes that appeared on the surface of the samples were investigated using Fourier transform infrared （FT4R） spectroscopy and attenuated total reflectance Fourier transform infrared （ATR- FTIR） spectroscopy after treatment for 2 min, 4 min and 6 rain in a nitrogen plasma chamber. Effects of the plasma treatment on the surface topographies and contact angles of the untreated and plasma treated films were also analyzed by atomic force microscopy （AFM） and a contact angle measuring system. The results show that the plasma treated films become more hydrophilic with an enhanced wettability due to the formation of some new polar groups on the surface of the treated films. Moreover, at higher exposure times, the total surface energy in all treated films increased while a reduction in contact angle occurred. The behavior of surface roughness in each sample was completely different at higher exposure times.

Effect of Electron Irradiation on Polypropylene Films

Effects of both electron beam irradiation on the properties of polypropylene （PP） films and the irradiation on the different layers of a multilayer PP film are studied. A Fourier transform infrared spectroscope was used to investigate the chemical structure of the films. The results showed that the chemical properties of the first layer were improved, that is, more functional groups responsible for dye ability and hydrophilicity of the film were produced on its surface, while noticeable improvement was not detected on the surface of other layers. This was also confirmed by testing the dye ability of the layers. However, the results obtained by atomic force microscopy showed that the electron irradiation caused some topographical changes, not only on the surface of the first layer but also on the others.

Surface Modification of Poly Vinyl Chloride (PVC) Using Low Pressure Argon and Oxygen Plasma

In this study, commercial poly vinyl chloride （PVC） films were treated by oxygen and argon plasmas in a cylindrical glass tube which was surrounded by a DC variable magnetic field, with different sample positions in the plasma reactor and also different exposure durations. Effects of the plasma treatment on the hydrophilic properties of the films were studied by mea- suring the water drop contact angle on the surface of the samples. The surface topography of the untreated and plasma treated films was analyzed and compared by atomic force microscopy （AFM）. The optical characteristic changes in treated samples were investigated using reflective spectrophotometry. Also, the chemical changes which appeared on the surface of the samples were investigated using Fourier transform infrared spectroscopy （FTIR）. The results show that the plasma treated PVC becomes more hydrophilic with an enhanced wettability. A sharp de- crease in the water contact angle may also be a consequence of the surface texturization. The aging effect on wettability of the samples was also investigated. The results show that the effect of oxygen plasma on the surface properties of the samples is more pronounced compared with that of argon plasma.

Structure,morphology and electrical resistance of W_(x)N thin film synthesized by HFCVD method with various N_(2) contents

Tungsten nitride(W_(x)N)thin films with good crystalline structure,high quality and relatively low resistivity were deposited by hot filament chemical vapor deposition(HFCVD)technique at different mixtures of N2 and Ar gases.Experimental data demonstrate that different N_(2) contents in gas mixture strongly affect microstructure,phase formation,texture morphology and resistivity of the W_(x)N films.According to X-ray diffraction(XRD)patterns,the growth of tungsten nitride films promotes δ-WN phase for lower N_(2) contents in gas mixture.At higher N_(2) contents,a phase transition is observed in the tungsten nitride films.Both hexagonal δ-WN and cubic β-W_(2)N phases coexist,and WN phase approximately disappears with N_(2) contents in the gas mixture increasing.Scanning electron microscope(SEM)images for deposited films at lower N_(2) contents in gas mixture indicate a definite dense columnar nanostructure.The electrical resistivity results exhibit a significant drop for the W_(x)N thin films with N_(2) contents in the mixed gas increasing.The changes in N_(2) content in gas mixture are found to be responsible for variation in the film resistivity values.Thus,the deposited tungsten nitride thin film at higher N_(2) contents in gas mixture has noncolumnar microstructure and lower resistivity,which may be used as a superior diffusion barrier.

Excellent photocatalytic performance under visible-light irradiation of ZnS/rGO nanocomposites synthesized by a green method

ZnS/graphene nanocomposites with different graphene concentrations （5, 10 and 15 wt.%） were synthesized using L-cysteine as surfactant and graphene oxide （GO） powders as graphene source. Excellent performance for nanocomposites to remove methylene blue （MB） dye and hexavalent chromium （Cr（VI）） under visible-light illumina- tion was revealed. TEM images showed that ZnS NPs were decorated on GO sheets and the GO caused a significant decrease in the ZnS diameter size. XRD patterns, XPS and FTIR spectroscopy results indicated that GO sheets changed into reduced graphene oxide （rGO） during the synthesis process. Photocurrent measurements under a visible- light source indicated a good chemical reaction between ZnS NPs and rGO sheets.