We demonstrated a method for selective etching of polyphenol–matrix composites which leads to improvement of the insulation properties. The selective polymer removal improved tracking properties of the 70% glass filler reinforced composites up to 56%, whereas the performance level decreased with the decrease in filler content. This technology provides an important enhancement of polymer–matrix composites' tracking properties and resistance of composites to electrical short-circuit fire.
COBISS.SI-ID: 28532263
The article reports on reciprocal influence between the sample surface and atmospheric plasma jet. We have shown that sample material and its distance from the tip of the electrode have a pronounced influence on atmospheric pressure plasma jet electromagnetic and optical characteristics, such as jet length, shape, color, voltage, current, power, electromagnetic field and concentrations of plasma species. Research was performed in collaboration with Institute of Physics, Zagreb.
COBISS.SI-ID: 28249127
The influence of RF generator frequency on plasma parameters was studied. Unlike other authors who use a single-frequency power supply we chose multiple harmonics in order to detect plasma behaviour in such a system. We found that the optical emission intensity of emitting plasma species correlates with the discharge current, whereas the jet length correlates with the voltage amplitude. A high discharge voltage is therefore suitable for treatment of insulating materials in gaps between the electrodes, but high efficiency in terms of selective removal of polymer from the composite surface can be obtained using lower circuit impedance (higher current).
COBISS.SI-ID: 27671591
Characteristics of ammonia plasma sustained by inductively coupled radiofrequency discharge has been studied in the range of powers between 50 and 1000 W and pressures between 10 and 90 Pa. In such an experimental setup pronounced differences between the E- and H-mode were observed and explained to some details. Plasma was characterized by optical emission spectroscopy (OES) and residual gas spectrometry (RGA). The plasma luminosity changed for 4 orders of magnitude and the NH2 band vanished at higher powers (H-mode). The RGA results indicated high density of NH2 radicals in the E-mode whilst in the H-mode the ammonia molecules almost entirely dissociated to H and N atoms. The N and H atoms created in the plasma recombined to the nitrogen and hydrogen molecules rather than to parent ammonia molecules on the way to the RGA.
COBISS.SI-ID: 30820135
Inductively coupled low temperature plasma discharge was verified to facilitate chemical etching to selectively remove the surface polymer from the glass filled polyphenolic composite. The etching rate inside the plasma was compared with commercially important feeding gases including H2, N2, O2 and NH3 as a function of discharge power. The protruding surface polymer was removed in volatile molecular fragments, whereas the glass additives stayed unaffected. The etching rate is shown to increase as a function of applied power inside all used gas discharges. Irrespective of the applied power, O2 plasma displayed the highest etching rate. Furthermore, by combining optical emission spectroscopy (OES) and X-ray photoelectron spectroscopy (XPS) analyses, the work is extended to mechanistically present the possible chemical pathways which lead to creation of various functional groups on the surface during the plasma–surface interactions.
COBISS.SI-ID: 6033434