Marcel Simor

Atmospheric-pressure diffuse coplanar surface discharge for surface treatments

We report results from a plasma source; a diffuse coplanar surface discharge (DCSD), which is capable of generating macroscopically uniform thin layers of diffuse plasmas in air and other reactive gases at atmospheric pressure. DCSD is a type of dielectric barrier discharge generated on the surface of a dielectric barrier with embedded electrodes, which appears to be advantageous to surface treatment and deposition processes. Preliminary results on hydrophilization of polypropylene nonwoven fabric are also presented.

Atmospheric-pressure plasma treatment of polyester nonwoven fabrics for electroless plating

Abstract Atmospheric-pressure non-thermal plasmas have been increasingly promoted for polymer surface modifications. In this paper, atmospheric-pressure nitrogen plasma was used to render a polyester nonwoven fabric hydrophilic and facilitate absorption of a palladium catalyst in order to provide a catalytic surface for the deposition of electroless nickel. The plasma was produced in a surface barrier discharge generating a thin plasma layer in good contact with the fabric fibers. The optimum quality nickel coating was obtained for a 1 s treatment time. Treatment times in excess of 1 s resulted in a reduction of the nickel plating deposition rate, uniformity and adhesion values. The plasma-induced surface changes were characterized by liquid strike-through time measurements, X-ray photoelectron spectroscopy, and scanning electron microscopy. Because of atmospheric-pressure operation, very short treatment times, and its robustness the method has the potential to be used in line with standard metal plating lines.

Hydrophilization of polypropylene nonwoven fabric using surface barrier discharge

Abstract Surface dielectric barrier discharges (SDBD), which find widespread industrial applications in ozone production, were used to hydrophilize light-weight polypropylene nonwoven fabric (PPNF) samples. The samples were treated in nitrogen plasma generated by SDBD at atmospheric pressure. The hydrophilicity of the samples was examined as a function of the storage time using a standard strike-through test. The surface chemical composition was characterized by X-ray photoelectron spectroscopy. Because of very short treatment times obtained (∼1 s) and its simplicity the method has the potential to be used in-line with standard high-speed PPNF production lines, laminating, printing and metal plating lines, etc.

The Influence of Surface DBD Plasma Treatment on the Adhesion of Coatings to High-Tech Textiles

The surface of high-performance poly(ethylene terephthalate) (PET) fibers is difficult to wet and impossible to chemically bond to different matrices. Sizing applied on the fiber surface usually improves fiber wetting, but prevents good adhesion between a matrix and the fiber surface. The present study demonstrates that the plasma treatment performed by Surface dielectric barrier discharge (Surface DBD) can lead to improved adhesion between sized PET fabric and polyurethane (PU) or poly(vinyl chloride) (PVC) coatings. Moreover, it points out that this plasma treatment can outperform current state-of-the-art adhesion-promoting treatment. Plasma treatment of sized fabric was carried out in various gaseous atmospheres, namely N2, N2 + H2O, N2 + AAc (acrylic acid) and CO2. The adhesion was assessed by a peel test, while wettability was evaluated using strike-through time and wicking rate tests. Changes in fiber surface morphology and chemical composition were determined using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. Only the CO2 plasma treatment resulted in improved adhesion. As indicated by the analyses, increased surface roughness and the incorporation of specific oxygen-containing groups were responsible for enhanced adhesion. The results presented were obtained using a plasma reactor suitable only for batch-wise treatment. As continuous treatment is expected to provide higher homogeneity and, therefore, even better adhesion, a scaled-up Surface DBD plasma system allowing continuous treatment is presented as well.

Mechanism for negative corona current pulse in CO2-SF6 mixtures

Current waveforms of first negative corona pulses have been measured in CO2–SF6 mixtures over a pressure range extending from 6.65 to 50 kPa and various overvoltages. Effects of changing cathode secondary electron emission were studied using a copper cathode coated by CuI and graphite. For a given set of experimental conditions it is concluded that in the mixtures containing up to 30% of SF6 the negative corona pulse is associated with the formation of a cathode-directed streamer-like ionizing wave in the immediate vicinity of the cathode. This is in contrast to the discharge behaviour in air–SF6 and N2–SF6 mixtures, where in similar conditions the discharge develops according to a multi-avalanche Townsend mechanism.