Catalytic Acetylation of Pinus radiata (D. Don) with Limited Supply of Acetic Anhydride Using Conventional and Microwave Heating

This study outlines the effect of catalyst (potassium acetate) and microwave heating on the rate and degree of acetylation in radiata pine. Sapwood samples were impregnated with potassium acetate dissolved in two different solvents (water and methanol). Catalyst loaded samples were dried and impregnated with acetic anhydride followed by conventional and microwave heating. The degree of acetylation was evaluated by weight percent gain (WPG) and characterized by Fourier transform infrared spectroscopy using attenuated total reflection (FTIR-ATR). Effect of catalyst loading, reaction temperature, and reaction time on the degree of modification and rate of reaction was investigated. A reaction time of 30 min gave rise to 20.6% weight gain in a catalyzed system while it was only 2.7% in uncatalyzed condition. No significant difference in the WPG and rate of reaction was found when water and methanol were used as solvents. Under catalytic condition 21.6% weight gain was obtained after 10 min of microwave heating. Potassium acetate was found to have no adverse effect on dimensional stability of wood.