MECHANICAL-PROPERTIES OF CHEMICALLY TREATED WOOD

Molecular configurations of cellulose, hemicelluloses and lignin molecules are well documented. All three polymers seem to constitute separate entities in wood, but the ultrastructure is not known; neither is known how the polymers act together to impart the properties which determine the industrial utilization of wood and its fibers. In an attempt to gain more knowledge, species of solid wood are treated with chemicals to produce swelling, substitution, etc., with measurements of mechanical properties on the same slender sample before and after treatment. Methods to measure axial stiffness, creep and axial compression strength are developed. The treatments give distinct changes, which may partly be related to individual polymers. Stiffness, creep and strength change "independently." Changes are sometimes slow and associated with a transient increase of creep.