Original paper(Vol.45 No.4 pp.376)

Effect of temperature on bending creep of wood during moisture adsorption

Tokumoto Morihiko; Takeda Takashi; Nakano Tatuo

Abstract:The effect of temperature (20 - 80 degree) on the bending creep of wood during moisture adsorption (7% yields 16%) and desorption (16% yields 7%) was investigated by using small beams of buna (Fague crenata Blume) and hinoki (Chamaecyparis obtusa Endl.) wood. The test specimens were 120 mm radially, 3 mm tangentially and 10 mm longitudinally. The span was 100 mm and the prescribed bending loads fitting to the test temperature were applied at the center of span. The final equilibrium moisture contents were attained in one step (fast) and in 7approx.8 steps (slow) by suitable humidity schedules in a testing chamber.
Creep during moisture desorption was not dependent on temperature between 20 degree and 80 degree. On the other hand, creep during moisture adsorption was dependent not only on temperature but also on time and the range of moisture content. The difference in temperature dependence of creep between the adsorption and desorption period may be explained based on the behaviour of the amorphous region composed of molecular network. Some possible explanations are given in terms of the response of the molecular network structure in the amorphous region during desorption and adsorption.

Key Words:bending creep, adsorption, desorption, effect of temperature, response of network structure