Characterization of non-thermal dielectric barrier discharges at atmospheric pressure in presence of microfibrillated cellulosic foams

Abstract

Plasma processing of sustainable polymers from renewable resources has recently gained significant interest. This work reports the ignition of plane-to-plane dielectric barrier discharges at atmospheric pressure operated in nominally high-purity helium with microfibrillated cellulose (MFC) foams derived from woody biomass taking up the entirety of the gas gap. Over the whole range of experimental conditions examined, discharge ignition and propagation mostly occurs through the foam from one electrode to the other (volume discharge). For outgassed foams, current–voltage characteristics suggest a glow-like discharge regime at 60 kHz and a filamentary behaviour at 10 kHz. However, optical imaging reveals localized emission patterns in both cases. Significantly less plasma-induced damage is observed through the MFC foams at 10 kHz than at 60 kHz. From these findings, the apparent homogeneous regime at 60 kHz seems to result from multiple discharges sustained in localized damaged zones. For non-outgassed samples exposed to the helium gas flow, gaseous species trapped in the MFC foams yielded to a significant increase of the discharge power and thus caused more significant damage to the cellulosic material.