Abstract
UDC 621.382:537.525
The results of the studies related to the effect of loading under the action of low-temperature air plasma on the surface of a polypropylene (PP) film are given. A gravimetric method was used to study the kinetics of the etching of the polymer. The formation rates of gaseous products and oxygen uptake rate at the air plasma treatment of the PP film at direct current discharge were obtained using mass-spectrometry. A longitudinal electric field strengths was determined by the current compensation technique in a two-probe circuit. The emission intensity of several oxygen and hydrogen atomic lines and N2, NO, CO emission bands were measured in order to determine rotational and effective vibrational temperatures of the N2(С3Πu) molecules, effective vibrational temperatures of the NO(A2Σ) state, concentration of O(3P) atoms. Numerical solution of the Bolzmann equation gave the electron energy distribution function (EEDF). It was shown that the presence of a polymer film leads to the 10% growth of the field strength but does not have any influence on the gas temperature. Even small loading of the reactor with a PP film brings in a definitely lower emission intensity of both the lines of atomic oxygen and N2, NO bands. A higher load results in the change of the ratio of the main PP film plasma-induced oxidative degradation products such as CO2, CO, H2O, H2. The calculated EEDF made it possible to analyze the action of the heterogenic reaction products on the rate coefficient for the electron impact excitation of some states. Gaseous products of PP film plasma-etching have a strong impact on electrophysical parameters of the discharge and the kinetic characteristics of etching. All that should be taken into account in future research and development of new technologies of plasma-processing of polymeres.
Keywords: loading effect, air plasma, plasma-chemical etching, gaseous products, reduced electric field strength, vibrational and rotational temperature of N2, kinetics.