Mechanical Properties of Acetylated Wood

Acetylation of wood produces increased dimensional stability and increases some strength, properties. Acetylated wood may be ideal for products where precision tolerances are required–this is one reason to study its properties. The tests done were run according to ASTM test standards on three species: Pinus ponderosa, Quercus rubra, and Acer saccharum. For each test an equal amount of treated and untreated samples were tested of equal size. Equilibrium moisture contents were less for the acetylated specimens. The reduction for the acetylated specimens in moisture content were 45 percent for oak, 56 percent for maple, and 63 percent for pine. Values of density were found to be higher for the acetylated specimens also. The density increases were 7.4 percent for maple, 9.0 percent for oak, and 9.8 percent for pine. According to the ASTM tests definite increases were found in compressive strength, hardness, fiber stress at the proportional limit, and work to the proportional limit. Other changes shown were an increase in pine and decreases in oak and maple for modulus of rupture. Modulus of elasticity remained constant with some decrease in shear strength parallel to the grain. Bulking, which was permanent, showed up in all treated specimens. The increases in strength values were believed to be due to the decrease in equilibrium moisture content and the increase in density.

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