Comparisons of the photostability of esterified wood

The light stability of wood panel treated with acetic anhydride, succinic anhydride, maleic anhydride, and phthalic anhydride was compared. Results from the solid state CP/MAS C-13 NMR analyses revealed that the esterification of holocelluloses occurred mainly at the C-6 position in the amorphous cellulose component. After lightfastness testing, the change in the color of wood treated with phthalic anhydride was greater than that subject to the other treatments. The color difference and yellowness index of acetylated wood after irradiation were significantly less than controls, indicating that acetylation inhibited the photoyellowing of wood. In addition, results obtained from diffuse reflectance UV-VIS spectral analyses clearly demonstrated that the amount of chromophores generated in wood treated with phthalic anhydride was more than that of the untreated control after photodegradation, and that the amount of chromophores on the irradiated acetylated wood surfaces was much less than that of the others. Acetylation reduced the formation of colored derivatives on the wood surfaces and consequently inhibited the photodiscoloration of wood. (C) 2001 Elsevier Science Ltd. All rights reserved.