Temperature dependence of the dynamic viscoelasticity of bases of Japanese cypress branches and the trunk close to the branches saturated with water

With the aim of obtaining findings on the dynamic properties of branches and their bases, as well as their support mechanisms, the present study examined the temperature dependence of the dynamic viscoelasticity of Japanese cypress samples saturated with water to clarify the responses in different regions, and identified factors influencing the characteristics. In the bases of the branches: E' sharply decreased at approximately room temperature and significantly decreased at around 20 and 60 A degrees C; a peak and shoulder peak of EaEuro(3) or tan delta were noted at around 20 A degrees C, and there was another peak of tan delta at around 60-80 A degrees C; and mechanical relaxation was noted at around 20 A degrees C and 60-80 A degrees C. On the other hand, in some regions, including the trunks, branches, and their bases, mechanical relaxation was only noted on the high-temperature side. However, boiling treatment with about 12 % weight loss inhibited mechanical relaxation, and there were decreases in E', EaEuro(3), and tan delta at approximately room temperature. The bases of the branches of Japanese cypress are considered to develop its elasticity and viscosity to tolerate external stress by accumulating an extract, which enhances the strength of lignin.