Grafting of gold nanoparticles on polyethyleneterephthalate using dithiol interlayer

Two different procedures of grafting of polyethyleneterephthalate (PET), modified by plasma treatment, with gold nanoparticles (nanospheres) are studied. In the first procedure the PET foil was grafted with biphenyl-4,4′-dithiol and subsequently with gold nanoparticles. In the second one the PET foil was grafted with gold nanoparticles previously coated by the same dithiol. X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and electrokinetic analysis were used for characterization of the polymer surface at different modification steps. Gold nanoparticles were characterized by ultraviolet–visible spectroscopy. The first procedure was found to be more effective. It was proved that the dithiol was chemically bonded to the surface of the plasma activated PET and it mediates subsequent grafting of the gold nanoparticles.     

Measurement of lifetimes of thin carbon stripper foils produced by ion-beam sputtering

Thin carbon stripper foils used in high-intensity proton accelerators and heavy-ion accelerators must have long lifetimes. Thin carbon foils were fabricated by ion-beam sputtering using reactive and inert gas ions. The lifetime of the foils was measured using a KEK 650-keV high-intensity DC H⁻ (negative hydrogen ion) beam; changes in the foil thickness and surface deformations during irradiation were investigated. The lifetime of a typical stripper foil fabricated by heavy-ion-beam (Ar and Kr) sputtering was 60-70 times longer than that of the best commercially available foils. This paper reports a fabrication method for carbon stripper foils, along with an investigation of their lifetimes and changes in foil thickness during beam irradiation.     

Influence of size effect on the springback of sheet metal foils in micro-bending

To analyze the unloading springback of sheet metal foils after micro-bending process, a constitutive model is proposed based on the surface layer model by which the sheet foil is divided into surface layer and inner portions. For the inner portion, each grain is envisaged as a composite, comprised of grain interior and grain boundary work-hardened layer. The classical composite model is then used to calculate its flow stress. For the surface layer portion, a model without grain boundary strengthening is constructed to represent the flow stress in this zone. The developed method is verified through the comparison of the calculated strain–stress curves with the tensile test results of four kinds of pure copper sheet foils with different thicknesses ranging from 0.1 mm to 0.6 mm. To investigate the effect of thickness and grain size on the springback of pure copper sheet foils, three-point bending tests are carried out. A finite element (FE) model for predicting the springback in micro-bending process is further developed, which takes into account the deformation behavior and orientation of each grain. The influences of grain size and thickness on the springback of sheet foils are investigated. The research results show that the decrease of sheet foil thickness or the increase of grain size results in a big springback. The scatter of springback angle is mainly attributed to the elastic anisotropy of surface grains and increases with the reduction of grains along the thickness direction. A good agreement between the experimental results and the analytical calculations shows that the developed FE model can predict the springback of sheet metal foils well in micro-bending process.     

Measurement of lifetimes of thin carbon stripper foils produced by ion-beam sputtering

Thin carbon stripper foils used in high-intensity proton accelerators and heavy-ion accelerators must have long lifetimes. Thin carbon foils were fabricated by ion-beam sputtering using reactive and inert gas ions. The lifetime of the foils was measured using a KEK 650-keV high-intensity DC H⁻ (negative hydrogen ion) beam; changes in the foil thickness and surface deformations during irradiation were investigated. The lifetime of a typical stripper foil fabricated by heavy-ion-beam (Ar and Kr) sputtering was 60–70 times longer than that of the best commercially available foils. This paper reports a fabrication method for carbon stripper foils, along with an investigation of their lifetimes and changes in foil thickness during beam irradiation.     

Effect of impurities in charge-exchange carbon foil on foil thickness reduction

Carbon thin foils are commonly used as a charge stripping material in particle accelerators. Depending on the original foil thickness, changes in thickness during beam irradiation vary: thin foils (∼10 μg/cm²) thicken by build-up, medium thickness foils (∼15 μg/cm²) remain unchanged, and thick foils (∼20 μg/cm²) become thinner. The thickness reduction differs even under identical manufacturing processes and conditions.The factor causing foil thinning is unknown. On the basis of the low sputtering rate of carbon, it can be said that impurities contained in the foil cause foil thinning.Carbon foils contain impurities such as water. These impurities dissociate and combine with carbon and then evaporate. Taking this into consideration, we examined the gas composition during beam irradiation, to determine which impurity causes foil thinning. As a result, we found that oxygen contained in the foil plays a role in foil thinning.     

Plastic anisotropy of ultra-thin rolled phosphor bronze foils and its thickness strain evolution in micro-deep drawing

Metal foils are highly advantageous for producing microcomponents with high-aspect-ratio three-dimensional shapes by miniaturizing the process dimensions in sheet-metal-forming technologies. To characterize existing rolled metal foils at manufacturing sites and to clarify the impact of its strong anisotropic properties on micro-sheet formability, tensile tests and micro-deep drawing tests were performed on phosphor bronze foils with thicknesses of 20–300 μm. Focusing on the Lankford value (r-value) as a useful parameter for conventional sheet-metal-formability, the relation between the r-value of ultra-thin rolled foil and its applicability in micro-deep drawing is investigated. Ultra-thin rolled foil is characterized with a higher r-value due to the strong texture of {1 1 0} and {1 1 1} textures. Although the in-plane tendency of the r-value showed a strong correlation with the thickness distribution of micro-drawn cups, the obtained higher r-value for thinner foils does not correspond to the lower formability of thinner metal foils. As relevant parameter for indicating the forming limit for thin-rolled metal foils, the nonuniformity in thickness due to surface roughening is introduced. The importance of a geometrical anisotropy, such as orientation of surface topography and defects, for the unstable deformation of ultra-thin rolled metal foils is experimentally demonstrated.     

Measurement of carbon sputtering yield by N ion beam and lifetime dependence of resulting foils on thickness

Carbon stripper foils with a higher nitrogen content were made by ion beam sputtering with reactive nitrogen gas. Such foils seem to be very useful as strippers for high-intensity heavy ion accelerators. To know further characteristics of the lifetime of such carbon foils, we have measured the sputtering yield of the carbon source material at a sputtering voltage of 4–15 kV and the lifetime dependence of such foils on thickness. Lifetime measurement was performed with a 3.2 MeV Ne⁺ ion beam. The sputtering yield on average showed 0.75 atoms/ion at over 9 kV sputtering voltage. The lifetime of the foils noticeably depends on the foil thickness, and the thickness range as practical stripper foil is to be around 15 to 33 μg/cm². Two foils made at 13 kV showed extremely long lifetimes of 6800 and 6000 mC/cm² at maximum and the foils made above 10 kV lived longer than about 900 mC/cm², which correspond to about 270 and 40 times longer than commercially available best foils. We measured the thickness ratio of nitrogen to carbon in each foil made at the different sputtering voltages and at the different irradiation stages (mC/cm²) by RBS method. We also inspected the structure of a nitrided carbon foil by transmission electron microscopy.     

Characterization and cytocompatibility of carbon films

Carbon layers on polyethyleneterephtalate (PET) backing were prepared by 3 different deposition methods as evaporation, sputtering and photo induced chemical vapor deposition. UV-Vis, Raman spectroscopy, Rutherford backscattering techniques, goniometry and electrical resistance measurement were used for the characterization of the layers. Surface morphology of the layers was determined by AFM technique and the thickness was determined by SEM and profilometry. Adhesion and proliferation of 3T3 cells by method in vitro were studied. It was found that the properties of the deposited carbon layer depend on the deposition method. The layers prepared by sputtering are composed from oxidized amorphous carbon in the form of disordered graphite. Contact angle of deposited carbon layers decreases in comparison to pristine PET. The electrical resistance of carbon layer also decreases, a dramatic decrease being observed especially after carbon flash evaporation. The carbon deposition has no significant influence on surface roughness, but the surface morphology is strongly influenced. Adhesion of 3T3 fibroblast didn't show any significant difference between PET, sputtered and CVD layers. Proliferation of 3T3 fibroblast has shows differences due to the surface morphology and also wettability of the surface which is linked to the chemical composition.     

A study of very thin DLC foils as a gas barrier

Measurements of vacuum tightness and mechanical strength of diamond-like carbon (DLC) foils in the thickness range of 1–7 μg cm⁻² have been performed with a purpose to evaluate suitability of foils as a gas barrier. Hydrogen and argon at pressures from 10⁻² Pa to 20 kPa were used as test gases. The permeation rate specified as conductance density was found for the best sample of self-supporting foil to be around 1.5×10⁻³ l and 3.3×10⁻⁴ l s⁻¹ cm⁻² for H₂ and Ar, respectively. Conductance density of the same foils mounted on the frames with a mesh along the apertures as support was about twice higher than that for the self-supporting ones, likely due to the mechanical imperfections of the foil assemblies of the first ones. On the other hand, mesh-supported foils as thin as 3 μg cm⁻² and of 5 mm in diameter were withstanding the pressure of up to 18 kPa, while self-supporting foils of the same thickness ruptured at around 1.2 kPa. There was no observed relation between thickness of the foil and its mechanical properties and permeation rate. This suggests that rather tears and pinholes present in foils are the limiting factors of the foil–vacuum tightness and strength. Results obtained in the studies, presented in this work, demonstrate the ability of very thin DLC to isolate a high vacuum beam line from a gas cell in a variety of applications and ability to withstand the gas pressure relevant, in particular, to some gas-filled ionization chambers.     

Fast and simultaneous growth of graphene,intermetallic compounds,and silicate on Cu–Ni alloy foils

A graphene bilayer was grown on copper–nickel alloy foils (30 at-% Ni: 70 at-% Cu designated as a 30Ni–70Cu) via an inductively coupled plasma–chemical vapor deposition chamber, and was characterized. The first layer fully covered the foil, while there was partial coverage of the second layer. At the same time, the alloy catalyst produced a compound of magnesium silicate in some regions and of copper sulfide in other regions on which a graphene monolayer simultaneously grew without any discontinuity or boundaries of the 1st graphene monolayer between simultaneous growth and graphene-only growth regions. Compared with Cu foils, the alloy foils led to faster growth of the graphene film in graphene-only growth regions, while maintaining the same quality, homogeneity, and thickness uniformity as a monolayer graphene grown on Cu. Raman spectroscopy and scattering demonstrated that the 2D and D bands of the Raman spectra were in the same position for the monolayer graphene on 30Ni–70Cu regardless of the grown regions and for the graphene on the Cu with a full width at half maximum of ∼38 cm⁻¹ ranging from 30 to 55 cm⁻¹ of 2D, and without a D band in the spectra of the graphene monolayer and bilayer. Thus the resulting graphene growth is affected primarily by the Cu catalyst, partly by the compounds grown simultaneously with the graphene monolayer on the foil surface via thermal reactions of the impurities dissolved in the alloy matrix, and partly by the Ni. The quality of the graphene is dependent on the major composition of Cu catalyst in the alloy foils. On the other hands, the alloying element of Ni governs the growth kinetics unless the alloy foils is covered with the intermetallic compounds and silicate.     

Influence of oxygen and nitrogen plasma treatment on polyethylene terephthalate (PET) polymers

In this paper we present surface modification of polyethylene terephthalate (PET) polymer, which is commonly used as synthetic vascular graft. Surface modification was made by oxygen and nitrogen plasma at different treatment times. Plasma was created by means of an RF generator at a discharge power of 200 W and gas pressure fixed at 75 Pa. The surface of PET polymer was modified in order to achieve improved attachment of fucoidan, which is a bioactive coating with antithrombogenic properties. In our study we analysed chemical modification of plasma treated surfaces by X-ray photoelectron spectroscopy (XPS), while the changes in morphology and surface roughness were observed with atomic force microscopy (AFM). Our results indicate that attachment of fucoidan is improved by oxygen plasma treatment, especially due to surface roughening.     

铝电解电容器用不同工艺腐蚀箔的对比研究

利用金相显微镜分析软质交流腐蚀箔、直交流腐蚀箔及硬质交流腐蚀箔的表面及断面蚀孔形貌,监测腐蚀箔恒电流阳极氧化过程中的升压曲线,并测试腐蚀箔阳极氧化后的比容、漏电流、抗拉强度及折弯次数.结果表明,软质交流腐蚀箔的蚀孔形貌呈灌木状;直-交流腐蚀箔的蚀孔呈乔木和灌木状分布,蚀孔中有部分大而稀疏的隧道孔,扩面倍率最小;而硬质交流腐蚀箔的蚀孔呈蜂窝状,孔洞细密,扩面倍率最大.直-交流腐蚀箔的漏电流最小,硬质交流腐蚀箔的抗拉强度及折弯次数最大.     

Improvement of adhesion of fucoidan on polyethylene terephthalate surface using gas plasma treatments

Attachment of polysaccharide fucoidan to the polyethylene terephthalate (PET) polymer surface was studied by X-ray photoelectron spectroscopy (XPS). Fucoidan has antithrombogenic and anticoagulant properties and is therefore a promising coating for vascular graft implants for improving their hemocompatibility. Samples of PET polymer were first modified by nitrogen plasma treatment in order to change the surface wettability and to introduce amino groups to the surface, which act as a linker for further binding of fucoidan. Plasma treated samples were then incubated for 30 min in fucoidan solution. The presence of fucoidan layer on the polymer surface was demonstrated by appearance of S2p signal in the XPS spectra of the coated PET samples. The procedure for immobilization of fucoidan on PET surface was optimized by varying pH value of fucoidan solution from 5 to 7.4. The best results were obtained when using lower pH value pH = 5. At these conditions the thickness of the fucoidan coating was estimated to about 7 nm.     

Plasma processing for surface optical modifications of PET films

The plasma interaction with the surface produces modifications of its chemical structure or morphology. Surface modifications through cold plasma occur, thanks to the high plasma reactivity and ability to affect the surface of materials.The present work shows the surface modification of polyethylene terephthalate (PET) films after the exposure both to low-pressure plasma (film deposition by plasma enhanced chemical vapour deposition) and to an atmospheric pressure dielectric barrier discharge (surface etching). After plasma treatment we have analysed the effect on the PET surface.For the atmospheric pressure plasma-treated samples, contact angle and atomic force microscope analysis enable us to determine roughness changes. For the low-pressure plasma samples, contact angles and Fourier transform infrared absorption spectroscopy analysis are used to estimate the chemical composition of the deposition and focused ion beam analysis to collect the image and calculate the thickness of plasma deposition.Both plasma treatments (film deposition and etching) cause changes in optical properties as indicated by reflectivity measurements.     

Plasma surface treatment of polymers with inductivity-coupled RF plasmas driven by low-inductance antenna units

Plasma surface treatment of polymers has been carried out with argon/oxygen mixture plasmas driven by multiple low-inductance antenna units. Kinetic energy distribution of argon ions from the argon/oxygen mixture plasmas onto polymers showed considerable suppression of ion energies sufficiently less than 10 eV. Polyethyleneterephthalate (PET) films were exposed to argon/oxygen mixture plasma for 1-5 min on a water-cooled substrate holder. The etching depth of PET surface increased with increasing plasma-exposure time and the etching rate was 118 nm/min. Surface roughness of PET surface (root-mean-square value) increased from 0.5 nm to 2.7 nm with increasing plasma-exposure time from 0 min (original sample) to 5 min. Hard X-ray photoelectron spectroscopy (HXPES) was carried out for analysis of chemical bonding states of the PET surface. The HXPES analyses exhibited nano-surface modification of the PET surface without suffering degradation of molecular structures beneath.     

Structural, chemical and biological properties of carbon layers sputtered on polyethyleneterephtalate

Carbon layers on polyethyleneterephtalate (PET) backing were prepared by sputtering from graphite target. UV-VIS, Raman spectroscopy, RBS (Rutherford backscattering) and ERDA (Elastic Recoil Detection Analysis) techniques were used for the characterization of the layers. Surface morphology of the layers was determined by AFM technique and the adhesion of 3T3 mouse fibroblasts on the layers was studied in vitro. It was found that the properties of the deposited carbon layer depend on the sputtering time. The concentration of conjugated double bonds, fraction of amorphous hydrogenated carbon (a-C:H) containing oxygen and surface roughness are increasing functions of the sputtering time. The changes of the layer surface morphology with increasing sputtering time were also observed. For the sputtering times up to 30' the number of adhering 3T3 cells increases with increasing sputtering time. For longer sputtering times, however, the cell adhesion becomes lower probably due to unfavorable changes in roughness and morphology of the layer.     

Characterization of beryllium foil produced by hot rolling

Beryllium foil is important for a number of aerospace applications including honeycomb structures and metal-matrix composites. In this study, a method of producjng beryllium foil directly from powder or flake is demonstrated. A variety of foils were produced in the thickness range 90–300 m, free from defects such as pinholes and excessive surface roughness, and exhibiting sufficient formability for honeycomb manufacture. Foil produced directly from powder or flake exhibits crystallographic texture, microstructure, and formability equivalent to foil produced from more massive precursors.     

PET recycled and processed from flakes with different amount of water uptake: characterization by DSC,TG, and FTIR-ATR

Recycled PET from bottles was processed from flakes, which containing different amounts of water uptake. After this process, they are subjected to characterization by differential scanning calorimetry (DSC), thermogravimetry (TG), and Fourier-transform infrared spectroscopy with an attenuated total reflectance accessory (FTIR-ATR). From the DSC and TG results it can be postulate an increase in the proportion of short-molecular-weight distribution in the PET chains, due to the hydrolytic degradation of recycled PET during the thermopressing in presence of water. This hydrolytic degradation probably formed more polar groups on the surface of the processed and recycled PET, like carboxyl groups, as observed by FTIR-ATR.     

Contact angle analysis of low-temperature cyclonic atmospheric pressure plasma modified polyethylene terephthalate

Polyethylene terephthalate (PET) films are modified by cyclonic atmospheric pressure plasma. The experimentally measured gas phase temperature was around 30 °C to 90 °C, indicating that this cyclonic atmospheric pressure plasma can treat polymers without unfavorable thermal effects. The surface properties of cyclonic atmospheric pressure plasma-treated PET films were examined by the static contact angle measurements. The influences of plasma conditions such as treatment time, plasma power, nozzle distance, and gas flow rate on the PET surface properties were studied. It was found that such cyclonic atmospheric pressure plasma is very effective in PET surface modification, the reduced water contact angle was observed from 74° to less than 37° with only 10 s plasma treatment. The chemical composition of the PET films was analyzed by X-ray photoelectron spectroscopy (XPS). Atomic force microscopy (AFM) was used to study the changes in PET surface feature of the polymer surfaces due to plasma treatment. The photoemission plasma species in the continuous cyclone atmospheric pressure plasma was identified by optical emission spectroscopy (OES). From OES analysis, the plasma modification efficiency can be attributed to the interaction of oxygen-based plasma species in the plasma with PET surface. In this study, it shows a novel way for large scale polymeric surface modification by continuous cyclone atmospheric pressure plasma processing.