木材の高温領域における力学分散(<小特集>木質材料小特集)

概要

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The temperrature dispersion of the elastic modulus of Hinoki wood (Chamaecyparis obtusa Sieb.et Zucc.) occuring at about 200℃ was investigated in longitudinal vibration at various frequencies.The results are summarized as follows. (1) There existed the elastic temperature dispersions in the elastic modulus across the grain E_R, the elastic modulus along the grain E_L and the elastic modulus in a direction 45 degree from the grain direction E_<45> below 250℃ at low frequencies from 1 Hz to 100 Hz. (2) The temperature of the dispersion shifted toward higher temperature as the measuring frequency became low. The values of the enthalpy of activation ΔH^≠, the free energy of activation ΔF^≠, and the entropy of activation ΔS^≠ for the elastic dispersion of wood were estimated (Table I). The values of the apparent activation energy of E_<45> was a little larger than that of E_R. (3) The temperature of the dispersion shifted toward higher temperature by repeating the measurement of the elastic modulus. It may be considered that changes of wood substance took place, for example crystallization or thermal decomposition by heat treatment.
社団法人日本材料学会の論文
1990-09-15