Plasma treatment of polypropylene fabric for improved dyeability with soluble textile dyestuff

The impact of plasma treatment parameters on the surface morphology, physical-chemical, and dyeing properties of polypropylene (PP) using anionic and cationic dyestuffs were investigated in this study. Argon plasma treatment was used to activate PP fabric surfaces. Activated surfaces were grafted different compounds: 6-aminohexanoic acid (6-AHA), acrylic acid (AA), ethylendiamine (EDA), acryl amide (AAMID) and hexamethyldisiloxane (HMDS). Compounds were applied after the plasma treatment and the acid and basic dyeing result that was then observed, were quite encouraging in certain conditions. The possible formed oxidizing groups were emphasized by FTIR and ATR and the surface morphology of plasma treated PP fibers was also investigated with scanning electron microscopy (SEM).PP fabric could be dyed with acid and basic dyestuffs after only plasma treatment and plasma induced grafting, and fastnesses of the dyed samples were satisfactory.     

On the thermoluminescence of textile fibres

U.V. excited thermoluminescence of ten textile fibres is investigated above liquid N₂ temperature. The results seem to indicate that the glow peak peculiarities are mainly due to structural defects or chemical impurities. The kinetic order of the process is always found to be 1.     

Influence of surface treatment on the electroless nickel plating of textile fabric

The present study is performed with an objective to acquire a deeper understanding of the properties of nickel-plated polyester fabric after conducing low temperature plasma treatment. Low temperature plasma treatment with oxygen and argon gases was employed to render a hydrophilic property of woven polyester fabrics and facilitate the absorption of a palladium catalyst in order to provide a catalytic surface for electroless nickel plating. The properties of plasma-induced electroless nickel-plated polyester fabrics were evaluated by various standard testing methods in terms of both physical and chemical performances.     

A novel surface treatment process for enhanced adhesion of ultra-high modulus polyethylene fibres to epoxy resins

Ultra-high modulus polyethylene (UHMPE) fibres have been treated using a novel 'non-plasma' treatment allowing the incorporation of various chemical functional groups onto the polymer surface. The process comprises two steps: corona discharge treatment, followed by silanization of the polymer surface by a solution of an organo-functional silane. Corona discharge treatment incorporates oxygen-containing functionalities, e.g. reactive hydroxyl groups, onto the polymer surface. The presence of reactive -OH groups provides the possibility of covalent linkage of any organo-functional silane to the corona discharge-treated polymer in the form of a fibre, film, sheet, or powder. The effectiveness of the process was assessed by examining the interlaminar fracture energy and flexural modulus and by SEM analysis of the fracture surfaces of composites fabricated from the untreated, corona discharge-treated, ammonia plasma-treated, and the amine-grafted (using the novel process) UHMPE fabric. A significant improvement in interfacial adhesion was confirmed by increases in the interlaminar fracture energies and flexural moduli. The effectiveness of the process investigated is similar to the ammonia plasma treatment. SEM analysis of the fracture surfaces indicated a change in the fracture mode from purely adhesive for unmodified fibres, through to mixed failure mode for corona-treated material, to highly cohesive-in-fibre surface for amine-grafted UHMPE fibres. XPS analysis confirmed the incorporation of the amine groups onto the surface of polyethylene treated using the novel method.     

D-shape polymer optical fibres for surface plasmon resonance sensing

We experimentally studied three different D-shape polymer optical fibres with an exposed core for their applications as surface plasmon resonance sensors. The first one was a conventional D-shape fibre with no microstructure while in two others the fibre core was surrounded by two rings of air holes. In one of the microstructured fibres we introduced special absorbing inclusions placed outside the microstructure to attenuate leaky modes. We compared the performance of the surface plasmon resonance sensors based on the three fibres. We showed that the fibre bending enhances the resonance in all investigated fibres. The measured sensitivity of about 610 nm/RIU for the refractive index of glycerol solution around 1.350 is similar in all fabricated sensors. However, the spectral width of the resonance curve is significantly lower for the fibre with inclusions suppressing the leaky modes.     

Identification of winter tires using vibration signals generated on the road surface

During the winter, traffic regulations state that automobile drivers must use winter tires on unsafe roads such as snowy expressways. The present report is concerned with the development of an automatic tire identification system that can discriminate winter tires from summer tires with high accuracy. The system detects the impact vibration signal that is specifically generated by winter tires when tread blocks with wide grooves strike the road surface during rolling. The signal is picked up by a commercially available vibration sensor. If the signal contains specified impact frequency components, the tire is judged to be a winter tire. Compared with the previous identification system, which used airborne tire/road noise, the proposed system has two advantages. First, it is unaffected by meteorological factors such as wind noise. Second, the proposed system performs well even when the target vehicle is traveling at low speed. We evaluate the performance of the system outdoors using a number of vehicles with various tires and demonstrate an overall improvement in identification accuracy for vehicles traveling at low or moderate speeds.     

Upper limit of bandwidth improvement by optical equalization of graded-index fibres

Optical equalization was suggested as a means for increasing the bandwidth of optical fibre communication links when non-optimal graded-index fibre profiles are available. In this paper it is shown that by proper choice of the length as well as of the index of the compensating fibre one can significantly increase the bandwidth capability of the link. An upper limit of this improvement is derived, which is much larger than that obtained with alternating fibres of equal lengths.     

Formation of surface membranes in developing mammalian hair fibres

Mammalian hair fibres result from complex mechanisms involving synthesis, assembly and stabilisation of keratin proteins in the follicle. The developing hair shaft consists of outer cuticle cells surrounding cortical and medullary (optional) cell types. Presumptive fibre cuticle (FC) is contained by the inner root sheath (IRS) consisting of IRS cuticle, Huxley and Henle cells which are in turn enclosed in an outer root sheath (ORS) of epidermal-like cells. In the current structural studies we have used energy filtered transmission electron microscopy (Zeiss 902A) on Merino sheep skin biopsies to examine the fine sequence of morphological changes involved in forming the fibre surface membrane and the associated underlying structural bands comprising the a-layer and exocuticle. Prior to the development of the exocuticle, FC cells demonstrate a typical plasma-membrane apposed to IRS cuticle plasma-membranes separated by an intercellular space. The formation of exocuticular lamellae is followed by degradation of the residual FC surface membrane and the appearance of intercellular laminae demonstrating a stained central band. As maturation continues cleavage between IRS cuticle and FC occurs along this central band liberating hair into the pilary canal. The mature surface consists of keratinized cells containing a well developed exocuticle and a-layer coated with paired lamina (presumably two lipid containing bilayers) of material approximately 10–12 nm thick derived from the intercellular laminae. The current observations show FC surface formation is similar to process occurring in epidermal stratum corneum and that the cuticle surface membrane of mammalian fibres is not derived from a modified plasma-membrane as previously documented.     

Short-time plasma surface modification of HDPE powder in a Plasma Downer Reactor - process, wettability improvement and ageing effects

The effectiveness of improving the wettability of HDPE powders within less than 0.1 s by plasma surface modification in a Plasma Downer Reactor is investigated. A correlation is revealed between the XPS results (O/C-ratio) and the wettability (contact angle, polar surface tension by capillary rise method). The O₂-content in the plasma feed gas has been adjusted for best wettability properties. XPS results indicate the formation of CO and COOH functional groups on the powder surface. The O/C-ratio increased from 0.0 (no oxygen on the non-treated powder) up to 0.15 for the plasma treated HDPE powder surface. With pure O₂-plasma treatment, a water contact angle reduction from >90° (no water penetration into the untreated PE powder) down to 65° was achieved. The total surface free energy increased from 31.2 to 45 mN/m. Ageing of treated powders occurs and proceeds mostly within the first 7 days of storage. Contact angle measurements and O1s/O2s intensity ratio data support that ageing is mainly a diffusion-controlled process. Nevertheless, XPS results show the presence of oxygen functional groups even after 40 days, which explains why the powder is still dispersible in water without any addition of surfactants.     

The surface modification of cellulose fibres for use as reinforcing elements in composite materials

The interest in using cellulose fibres as reinforcing elements in composite materials based on polymeric matrices is constantly growing, mainly because of the many advantages associated with this renewable material. However, the preparation of cellulose-based composites is perturbed by the highly hydrophilic character of the fibres, which is associated with a low interfacial compatibility with hydrophobic polymeric matrices, as well as with a loss of mechanical properties after moisture uptake. In order to reduce the hydrophilic character of cellulose fibres and to improve the strength of their adhesion to the matrix, it is necessary to undertake a structural modification of their surface. Several approaches have been studied, namely (i) physical treatments such as corona, plasma, laser, vacuum ultraviolet and γ-radiation treatments; (ii) chemical grafting by direct condensation, including surface compatibilisation with hydrophobic moieties and co-polymerisation with the matrix. The copolymerisation approach called upon different strategies: (i) The use of bi-functional molecules capable of reacting with the OH groups of the cellulose surface and leaving the second functions available for further exploitation; (ii) The direct activation of the surface and the subsequent graftingfrom polymerisation; and (iii) The condensation of organometallic compounds, followed by their coupling with suitable reactive molecules or macromolecules. The characterisation of the modified surfaces involved a variety of techniques, including elemental analysis, contact angle measurements, inverse gas chromatography, X-ray photoelectron and FTIR spectroscopy, water uptake, etc. The present survey reviews the different approaches proposed in the literature and critically assesses their respective merits and drawbacks.     

Plasma treatment of wood

Plasma technology was developed to create protective-decorative coatings on the wood surfaces. Experimental investigation on applying the protective coating using the low-temperature plasma energy as well as studies of the distribution of temperature fields over the section of the treated workpiece have been carried out, and the calculated results have been compared with the experimental data.     

Indium tin oxide surface treatments for improvement of organic light-emitting diode performance

We have systematically investigated the influence of UV ozone and acid (HCl) treatments (separate and combined) of the surface of indium tin oxide (ITO) on the ITO parameters and the performance of organic light-emitting diodes (OLEDs) fabricated on the treated substrates. The ITO substrates were characterized by Hall measurements, Seebeck coefficient measurements and surface-probe microscopy. After ITO characterization, two types of devices (ITO/NPB/rubrene/Alq₃/LiF/Al and ITO/TPD/rubrene/Alq₃/LiF/Al) were fabricated on the differently treated substrates. It was found that in both cases the optimal treatment was HCl followed by UV ozone, which resulted in the lowest turn-on voltage and the highest luminous efficiency. The maximum luminous efficiency in the ITO/NPB/rubrene/Alq₃/LiF/Al OLED with HCl followed by UV ozone treatment was 2.15 lm/W compared to 1.46 lm/W with UV ozone treatment only. PACS 81.65Cf; 85.60.Jb     

Plasma and surface tension model for explaining the surface effect of tritium generation at cold fusion

Summary For explaining the surface mechanism of deuterium reactions in palladium and titanium (clod fusion or neutron swapping) leading to strong tritium production and isotope shifts in palladium, the mechanism of an exotic deuterium plasma with possible short nuclear distance by thermal motion was introduced. Using a new model of the surface tension of metals, resulting in a ?swimming electron layer?, the increase of the concentration of deuterons and the decrease of their distance cause a higher cold fusion in the surface layer by orders of magnitudes compared with the bulk material. The work of one of the authors (H. Hora) was supported by the Wilhelm-Heinrich and Else Heraeus Foundation, Hanau, while being on leave at the University of Giessen, Germany.     

Scanning probe microscopy examination of the surface properties of keratin fibres

A Scanning Probe Microscope (SPM) was used to investigate the mechanical properties of the surface of hair and wool fibres. Using stiff cantilevers, penetration was achieved on the fibres under ambient conditions and at increased relative humidity (RH). The Young's modulus of the exocuticle was estimated to be 2.1GPa under ambient conditions, decreasing to 0.6GPa at 96% RH. Contrary to findings by other authors [Crossley, J.A.A., Gibson, C.T., Mapledoram, L.D. , Huson, M.G., Myhra, S., Pham, D.K., Sofield, C.J., Turner, P.S., Watson, G.S., 2000. Atomic force microscopy analysis of wool fibre surfaces in air and under water. Micron 31, 659-667; Gibson, C.T., Watson, G.S., Mapledoram, L.D., Kondo, H., Myhra, S., 1999. Characterisation of organic thin films by atomic force microscopy-application of force vs. distance analysis and other modes. Applied Surface Science 144-145, 618-622; Blach, J., Loughlin, W., Watson, G.S., Myhra, S., 2001. Surface characterization of human hair by atomic force microscopy in the imaging and f-d modes. Journal of Cosmetic Science 23, 165-174], the surface lipid layer could not be penetrated using soft cantilevers in force-distance (f-d) mode in water. Attempts were made to remove the lipid layer from the surface both physically and chemically so as to examine the influence of the lipid on f-d measurements. Using both techniques, it was not possible to remove lipid without damaging the fibre, suggesting that the lipid is an integral part of the surface rather than a discrete surface layer. Adhesion measurements on the surface of wool, nylon and polyethylene, showed that in water and at high RH, the surface of keratin fibres is more akin to a polyamide. At low RH and in liquid paraffin, the surface is more akin to a hydrocarbon, suggesting it is capable of altering its structure in response to different environments.     

Atomic force microscopy characterization of the surface wettability of natural fibres

Natural fibres represent a readily available source of ecologically friendly and inexpensive reinforcement in composites with degradable thermoplastics, however chemical treatments of fibres are required to prepare feasible composites. It is desirable to characterize the surface wettability of fibres after chemical treatment as the polarity of cellulose-based fibres influences compatibility with a polymer matrix. Assessment of the surface wettability of natural fibres using conventional methods presents a challenge as the surfaces are morphologically and chemically heterogeneous, rough, and can be strongly wicking. In this work it is shown that under atmospheric conditions the adhesion force between an atomic force microscopy (AFM) tip and the fibre surface can estimate the water contact angle and surface wettability of the fibre. AFM adhesion force measurements are suitable for the more difficult surfaces of natural fibres and in addition allow for correlations between microstructural features and surface wettability characteristics.     

Identification of single archaeological textile fibres from the cave of letters using synchrotron radiation microbeam diffraction and microfluorescence

Single 2000-year-old archaeological fibres from textile fragments excavated in the Cave of Letters in the Dead Sea region were investigated by a combined approach using microscopy (optical and SEM), X-ray microbeam diffraction and X-ray microbeam fluorescence. In comparison with modern reference samples, most of the fibres were identified as wool, some as plant bast fibres (flax). The molecular and supermolecular structure of both keratin (wool) and cellulose (flax) were found completely intact. In many fibres, mineral crystals were intimately connected with the fibres. The fluorescence analysis of the dyed wool textiles suggests the possible use of metal-containing mordants for the fixation of organic dyes. PACS 61.10.Nz; 78.70.En; 81.05.Lg     

Study of surface treatment processes for improvement in the wettability of silicon-based materials used in high aspect ratio through-via copper electroplating

We report the improvements in wetting characteristics of silicon-based materials with copper electrolyte by various surface treatments to achieve uniform and void free copper deposition in high aspect ratio through-via electroplating. The contact angles of samples such as native silicon, thermally oxidized silicon, silicon nitride, deep reactive ion etched silicon etc, with copper electrolyte, were measured before and after the surface treatments. The wetting of copper electrolyte with silicon nitride coated silicon samples was found to be more than that with thermally oxidized samples. Due to its better wettability, silicon nitride was later used as an insulating layer instead of commonly used silicon oxide in the electroplating experiments. After the SC1 wet surface treatment, the contact angles of all the samples were found to be significantly lower, thus making the surface more suitable for electroplating applications. X-ray photoelectron spectroscopy results verified the presence of polar functional groups on the samples surface, which has helped to improve wetting with copper electrolyte. The conclusions drawn by the experimental results were employed in the high aspect ratio through-via copper electroplating; and void free copper interconnects, having aspect ratio as high as 20, were fabricated.     

Methods to determine surface energies of natural fibres: a review

To tailor the interaction across composite interfaces especially for the development of green composites, i.e. composites made completely from renewable materials, information about the fibre surfaces is required. We review the current state of the art of methods to determine the surface tension of natural fibres and discuss the advantages and disadvantages of techniques used. Although numerous techniques have been employed to characterise surface tension of natural fibres, it seems that commonly used wetting techniques are very much more affected by the non-ideal character of natural fibres. Inverse Gas Chromatography (IGC) is a much better suited technique to determine the surface energetic properties of natural fibres than wetting techniques. The surface tension of natural reinforcements, determined using IGC, was reported for nanosized bacterial cellulose as well as bamboo, cornhusk, flax, hemp and sisal, covering a wide range of cellulose content. The effect of methods to separate/extract fibres from the plants as well as of a few surface modification procedures on the fibre surface properties is also reviewed. The dispersive part of the natural fibre surface tension γ ^d _S varies from 32 to 61 mJ/m². The fibre surface tension increases with increasing cellulose content of natural fibres. We also found that a higher basicity (Donor Number, K _B to Acceptor Number, K _Aratio) was observed for fibres containing more cellulose. This may be reflective of higher crystalline cellulose content in the surfaces of the fibres, as only the ether linkage of the cellulose is labile for hydrogen bonding.     

Optimization of the alkali treatment process of date palm fibres for polymeric composites

The global interest in environmentally friendly material over the past few years has led to the development of new research areas in the field of renewable materials and biocomposites. Within this scope, several researches have been conducted to modify natural fibres aiming at an improved compatibility with polymeric matrices. In this study, fibres from the spadix stem of the date palm tree were treated with sodium hydroxide over different times. The effect of the alkali treatment on the structure, thermal and mechanical behaviour of the fibres was verified through chemical analysis, FTIR spectroscopy, TGA, and tensile testing. Comparing the different alkalisation parameters, promising results are obtained with a 2% sodium hydroxide solution over a treatment time of 2 h.     

Plasma hydrogenated,reactively sputtered aluminium oxide for silicon surface passivation

The intentional addition of hydrogen during reactive sputtering of AlO_x films has led to a dramatic improvement of the surface passivation of crystalline silicon wafers achieved with this technique. The 5 ms effective minority carrier lifetime measured on 1.5 Ω cm n‐type CZ silicon wafers is close to the 6 ms of a control wafer coated by atomic layer deposition (ALD) of AlO_x. Hydrogen‐sputtered films also provide excellent passivation of 1 Ω cm p‐type silicon, as demonstrated by an effective lifetime of 1.1 ms. It is likely that the improved passivation is related to the formation of an interfacial silicon oxide layer, as indicated by FTIR measurements. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)