Temperature dependences of the dynamic viscoelastic properties of wood and acetylated wood swollen by water or organic liquids

In this study, to summarize the changes of thermal-softening behaviors of wood and acetylated wood due to differences in the kinds of swelling liquids, the following measurements were conducted. Untreated and acetylated wood samples were swollen by various liquids and the temperature dependences of the dynamic viscoelastic properties were measured after the heating and cooling histories were unified among the samples. The results obtained are as follows. Untreated samples swollen by high-polarity liquid had lower peak temperature of tan delta, however acetylated samples had higher peak temperature of tan delta than those of untreated wood. On the other hand, untreated wood samples swollen by low-polarity liquid had higher peak temperature of tan delta, however acetylated samples had lower peak temperature of tan delta than those of untreated wood. The amount of swelling is determined by interaction between wood and liquid due to proton-accepting power and molar volumes of liquid and so on, therefore the peak temperature of tan delta and degree of reduction in dynamic elastic modulus (EA ') with increasing temperature were corresponded to the amount of swelling.