TEMPERATURE-DEPENDENCE OF DYNAMIC VISCOEL ASTICITIES OF CHEMICALLY TREATED WOODS

The temperature dependence of dynamic viscoelastic properties of five kinds of chemically treated woods as well as untreated wood was invest igated. Three relaxations were detected in the untreated wood. They we re attributed to the micro-Brownian motion of the cell wall polymers, the motion of adsorbed water molecules, and the motion of CH2OH groups in the order of the decreasing temperatures at which they occurred. T he formalization treatment restricted the micro-Brownian motion to som e extent by the crosslinking of chains by OCH2 bridges and induced the relaxation attributed to the motion of OCH2 groups. Both the acetylat ion and propylene oxide treatments activated the micro-Brownian motion by the introduction of bulky groups and led to the relaxations due to the motions of the COCH3 and OCH2 groups, respectively. In the treatm ent with methyl methacrylate, relaxations attributed to the segmental motion of the main chain and the motion of the side chain of polymethy l methacrylate, in addition to the relaxations observed in the untreat ed wood, were detected. The impregnation of polyethylene glycol with a n average molecular weight of 1,000 into the cell walls activated the micro-Brownian motion and restricted the segmental motion of polyethyl ene glycol molecules.