Abstract

Bamboo utilization is restricted by its tubular culm. An attempt was made to understand flattening mechanisms of a half-tubular bamboo culm in hot linseed oil. The half tubular culm of Dendrocalamus asper Backer was pressed into a flatter shape under a constantly applied load while being softened in hot linseed oil. Specimen height, used to calculate the degree of flatness, was recorded as a function of time. Effects of linseed oil temperature (80–180 °C) and properties of bamboo specimens, i.e. initial moisture content (0–46 %), volume fraction of vascular bundles (35–55 %) and thickness (3–5 mm), on the flattening behavior were examined. The presence of moisture in bamboo reduced the temperature at which deformation began and increased the final board flatness. Higher volume fraction of vascular bundles reduced the rate of deformation. Linseed oil temperature of at least 120 °C was required to achieve good quality flat boards and to avoid immediate springback after load removal. Flattening of relatively thick bamboo specimens was limited as a result of non-uniform softening throughout the specimen thickness.