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.

Multi-hollow surface dielectric barrier discharge: an ozone generator with flexible performance and supreme efficiency

“…Since the correct evaluation of ozone production yield requires precise determination of the discharge power, the concentration of ozone and the working gas flow, considerable attention was devoted herein to measurements of them. It was confirmed and experimentally demonstrated (even though both current-and charge-based methods are in principle equivalent) [52] that Lissajous figure methods serve best for correct determination of the discharge power, while determination of power through the direct integration of the product u(t)i(t), where i(t) is measured by Pearson current probe, leads to systematically lower values of the power calculated (by a factor of 0.7), leading to notable overestimation of the ozone production yield.…”

Pin-to-plane self-pulsing discharge in transversal airflow: interaction with a substrate of plasma filaments blown out from the discharge zone

“…Eventually, the decay processes lead to the RPS amount diminishing and to shortening of the effective plasma jet length enriched with RPS. The said effect is especially strongly expressed in the plasma jets created by discharge in the longitudinal airflow-their visible length is much shorter in comparison with the length of the plasma jets created in the flow of He and Ar [32]. To be fair, we will note that under some conditions (but not always) the propagation of ionization waves ('plasma bullets') along the plasma jet is possible.…”

Plasma degradation of contaminated PPE: an energy-efficient method to treat contaminated plastic waste

“…The emergence of surface-bound N species is clearly observed in the N 1 s XPS data with the appearance of features at around 401.3 and 400.9 eV that are consistent with N–(C = O)– and C-NR 2 (R = C, H) moieties. This is not surprising given the presence of N atoms in the air plasma 35 , 36 , 41 , 42 . However, ground state N ( 4 S) is known to be unreactive to saturated hydrocarbon species and is only likely to react with CH 2 or CH radical centres already present on the polymer surface yielding chemically bound N moieties 43 , 44 .…”