熱帯産材の粘弾性(第1報) : 加熱乾燥による収縮について

It has been thought hitherto that a remarkable creep occured at some period of drying, and this was assumed to be due to the plastic nature of wood, derived from the non-equilibrium of moisture.
This report deals with the rheological properties of three tropical woods. In the present paper is discussed the shrinkage of tropical wood during drying. For the examination of this paper, there are used thin specimen(300μ thickness) of radial plane of sliced veneer of three tropical woods(Spinarl : Anisoptera thurfer, Manggasinoro : Shorea philippinensis, Makore : Minusops hecklii). The experimental temperatures were 40゜, 60゜ and 80℃. The shape and dimension of the specimens are shown in Fig. 1. Test specimens were dried from the initial moisture content of about 290% to 5%. (Fig. 2)
Experimental results are summarized as follows :
The shrinkage during drying at 40゜, 60゜ and 80℃ are shown in Fig.3, 4 and 5, and the relation between the rate of shrinkage per unit time and drying time from green condition at 40゜, 60゜ and 80℃. are shown in Fig. 6, 7 and 8.
1 ) In the drying of sliced veneer, the shrinkage is dependent on the arrangement of structure and specific gravity of wood.
2 ) The maximum value for the rate of shrinkage per unit time is hardly dependence on the temperature, but the moisture content for the maximum value of rate of shrinkage per unit time exists between 40 and 50% without regard to temperature.