EFFECT OF HUMIDITY ON VIBRATIONAL PROPERTIES OF CHEMICALLY-MODIFIED WOOD

Changes in vibrational properties of wood can be used to determine cha nges in the wood cell wall resulting from chemical modification. The d ynamic Young's modulus to specific gravity ratio (E'/gamma) and intern al friction (tan delta) for chemically modified wood compared to those for untreated wood showed major differences in cell-wall modification and lumen filling modification. Increasing the moisture content of th e cell wall also has a major effect on the vibrational properties of c hemically modified wood. In general, treatments that resulted in lower ing the moisture content of the cell wall also lowered internal fricti on within the cell wall. Vapor phase reactions with formaldehyde had t he greatest effect in stabilizing the cell wall against changes in dyn amic mechanical properties with increasing moisture content.