Chemical and morphological modification of softwood and hardwood surfaces by an oxygen glow discharge plasma

High-energy radiation preferentially degrades cellulose and enriches lignin content at wood surfaces particularly in hardwoods. Accordingly, we hypothesize that a similar effect will occur at surfaces exposed to plasma. We test this hypothesis by plasma-treating pine and poplar veneers and assessing changes in the lignin and holocellulose-derived sugar-content of veneers; quantifying etching of pellets containing lignin and cellulose, and observing etching of different cell wall layers in pine and Homalium. The majority but not all of our results support our hypothesis. Lignin-rich regions of wood cell walls were easier to see after plasma treatment. We discuss the potential uses of plasma-etching for the study of wood ultrastructure and the creation of wood surfaces with self-bonding properties, and conclude that plasma-etching can be used as an alternative to chemical pretreatments for ultrastructural studies of the distribution of lignin in wood cell walls.