Properties of chemically and mechanically isolated fibres of spruce (Picea abies [L.] Karst.).: Part 2:: Twisting phenomena

The twisting behaviour of chemically and mechanically isolated fibres of spruce (Picea abies [L.] Karst.) was examined. Mechanical isolation was carried out using very fine tweezers to obtain fibres with an unmodified cell wall assembly. Chemical isolation was achieved using hydrogen peroxide and glacial acetic acid, leading to partial degradation of lignin and hemicelluloses. Besides normal adult wood, compression wood and opposite wood fibres were investigated. Fibre twisting while drying increased with higher microfibril angles in the S2 layer, and was significantly less pronounced for mechanically isolated compared to chemically macerated fibres. A simple model is introduced that takes into account the interdependency between lateral cell-wall shrinkage and the microfibril angle in the S2 cell wall.