Dimensional Stability and Dynamic Viscoelastic Property of Wood Acetylated with Acetic Anhydride Solution of Glucose Pentaacetate

Spruce wood specimens were acetylated with a 3-15% acetic anhydride (AA) solution of glucose pentaacetate (GPA) at 120 degrees C for 8hrs, and their dimensional stability and viscoelastic property were compared to those of the untreated and normally acetylated ones. The GPA was certainly introduced into the wood cell wall during the acetylation and it gave higher dimensional stability. At room temperature, the dynamic Young's modulus (E) of wood along the radial direction was enhanced by 10% with the introduction of GPA, while its mechanical loss tangent (6) remained unchanged. These changes indicated the anti-plasticising effect of GPA molecules in the wood cell wall. On heating in the absence of moisture, the GPA-acetylated wood exhibited a marked drop in E' and a clear delta peak above 150 degrees C, whereas the E' and delta of the untreated wood were quite stable up to 200 degrees C during the measurement. The remarkable thermal softening of the GPA-acetylated wood was attributed to that of wood components plasticised with GPA.