T. G. Shikova

Mechanism of hydrogen peroxide formation in electrolytic-cathode atmospheric-pressure direct-current discharge

The kinetics of buildup of hydrogen peroxide in an atmospheric pressure direct-current discharge with a distilled-water cathode has been experimentally measured. A kinetic reaction scheme has been proposed and analyzed to calculate peroxide concentrations in accordance with experimental data.

Reaction of Oxygen Plasma Active Species with Polyethylene

The composition of the polyethylene surface upon treatment in an oxygen plasma and its afterglow was studied by attenuated total reflectance IR spectroscopy and X-ray photoelectron spectroscopy. The oxidation of the surface at the lowest destruction rates was attained upon simultaneous action of excited O2(a1Δg) and ground-state oxygen molecules. However, O(3P) atoms are involved in both the formation of oxygen-containing groups and their destruction accompanied by polymer degradation.

Degradation kinetics of phenol and its decomposition products in the electrolyte cathode of direct-current atmospheric-pressure discharge

The degradation kinetics of phenol and the formation kinetics of its decomposition products in the liquid cathode (distilled water) of direct-current atmospheric-pressure discharge in air have been experimentally measured. The processes occurring in the liquid phase have been simulated on the basis of the previously proposed reaction kinetics scheme complemented by phenol decomposition reactions and the formation/decay reactions of its degradation products.

The oxidative modification of polypropylene surface in electrolytic-cathode atmospheric-pressure discharge

The effect of electrolytic-cathode atmospheric-pressure discharge in air on the surface of polypropylene immersed in a solution and on the hydrogen peroxide formation efficiency was studied. It was found that iron(II) sulfate admixtures lead to a substantial increase in the concentration of oxygen-containing groups on the surface and to a decrease in the concentration of hydrogen peroxide in the solution. A possible interpretations of the results is given.

Surface Oxidation and Degradation of Polyethylene in a Mixed Argon-Oxygen Plasma

Changes in surface chemical composition and the rates of formation of gaseous degradation products under the action of a mixed argon-oxygen plasma on polyethylene (PE) were studied using multiple attentuated total internal reflection (MATIR) IR spectroscopy and mass spectrometry. It was found that the dilution of a gas mixture with argon decreased the rate of degradation of the material at argon contents higher than 30%. It was demonstrated that absorbance at the absorption bands of the main oxygen-containing groups in a PE film remained unchanged over an argon concentration range from 0 to 90%. Conceivable mechanisms of processes occurring in gas and solid phases, which allowed us to describe the phenomena observed, are discussed.

The Formation Kinetics of Gaseous Products at the Initiation Step of the Oxidative Degradation of Polyethylene in an Oxygen Plasma

The results of measurements of the rates of oxygen consumption and gaseous product formation at the initial stage of the action of an oxygen plasma and its flow-afterglow zone on the surface of low-density polyethylene films are given. It was found that degradation is a multichannel process in both plasma and afterglow zones, which begins with the abstraction of hydrogen molecules without the direct binding of gas-phase oxygen. Conceivable channel mechanisms are discussed.

Kinetic Features of the Formation of Gaseous Products upon Oxygen-Plasma Surface Treatment of Polyethylene, Polypropylene, Poly(ethylene terephthalate), and Polyimide Films

The results of measurements of the rates of mass loss, formation of gaseous products, and oxygen consumption during the surface treatment of polyethylene, polypropylene, poly(ethylene terephthalate), and polyimide films in a low-pressure oxygen plasma are reported. It was shown that CO2 and H2O were produced in the same process involving O(3P) atoms for all polymers, and the kinetic characteristics of the process were determined. The specific features of the plasma-enhanced oxidative degradation associated with the chemical composition of repeating units of these materials are discussed.