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In this study, the effect of an atmospheric-pressure plasma treatment on the surface properties of sugar maple (Acer saccharum March.) and black spruce (Picea mariana (Mill.) was analyzed by contact angle measurement and a water-based coating pull-off testing. The plasma gases used were Ar, N2, CO2, and air. It was found that the wettability with water and the coating adhesion of maple and spruce can be highly influenced by the nature of the plasma gas used and the plasma treatment time. For example, in the case of sugar maple, coating adhesion increased by 66% after 1.5 s of exposure to argon plasma. Repetition of the contact angle measurement one and two weeks after the initial plasma treatment showed that the plasma-induced modification is not permanent. Improvements in wettability and adhesion were also obtained with simpler, cheaper air plasmas, a result promising for the development of advanced plasma reactors operating at atmospheric pressure, specially designed for the wood industry.

The effect of O 2 addition in the gas feed of an open-to-air N 2 -O 2 dielectric barrier discharge (DBD) on the surface modification of sugar maple hardwood samples is reported. After treatment by N 2 -O 2 plasma, an increase of the contact angle with water and a decrease of the contact angle with diiodomethane was observed. X-ray photoelectron spectroscopy and Fourier-transform infra-red analyses further reveal a decrease of the O/C as well as increase of the C=O peak and surface aromaticity. When O 2 is added to the nominally pure N 2 DBD, the discharge transits from a homogeneous regime to a filamentary regime with increased dissipated power and neutral gas temperature. As a result, surface modification by N 2 -O 2 plasmas becomes similar to those occurring under a low-temperature heat treatment of wood surfaces. In such conditions, a mechanism involving the thermally-activated deacetylation and depolymerisation of hemicelluloses and cross-linking between lignin and furfural and hydroxylmethylfurfural, leading to the increase of wood hydrophobicity is proposed.

The interaction between hardwood (Sugar Maple) and softwood (Black Spruce) surfaces and N and O atom species produced in the flowing late afterglow of a surface‐wave microwave plasma column in N2‐O2 gas mixtures was investigated using a NO titration method combined with optical emission spectroscopy. Results showed two distinct atom loss regimes following their interaction with wood surfaces: a recombination regime at low oxygen concentrations (<1% O2) and an etching regime by O atoms at higher oxygen concentrations (>1% O2). The etching reaction was confirmed by surface profilometry measurements, with the formation of sub‐millimetre trenches between low‐density early wood and high‐density late wood regions. Recombination dynamics of O and N atoms over smooth and roughened wood regions are also compared.