On the composition of reactive species in air plasma jets and their influence on the adhesion of polyurethane foam to low-pressure polyethylene

Abstract

In this paper, non-thermal plasma sources based on the high-frequency sinusoidal coaxial dielectric barrier discharge (DBD) using fast flowing ambient air as feedstock gas at atmospheric pressure are described. These single- and multi-tube sources are able to generate low- and high-power turbulent plasma jets. Experimental results on both the spatio-temporal behavior of plasma inside the DBD and parameters of plasma jet(s) outside the discharge zone are presented. These results are complemented by information on the composition of reactive species generated by high-power airflow DBD. This information has been obtained from analysis of the emissive spectra of the discharge zone and plasma jet in the UV–visual region. The basic set of elementary plasma-chemical processes responsible for the generation of reactive species in the discharge zone and their further changes in hot air plasma jet is also presented. Although the oxygen concentration in the working gas is high, the concentration of reactive species in the plasma jet is enough for effective surface treatment. This is proved by the essential improvement in the adhesion of polyurethane foam (PF) to low-pressure polyethylene (PE) after treatment by the hot air plasma jet. The changes in the spatial microstructure of the scaffolds on PE surfaces taking place after plasma treatment have been established. The reasons for the adhesion improvement are discussed. The results obtained are of both scientific and practical interest, since PE pipes covered with PF are used in the housing and community sectors, the oil and gas industry, etc.