アミン類による木材の膨潤と剛性の変化

Abstract

膨潤剤による木材の可塑化の基礎的問題として, ヒノキおよびマカンバを用いて, 木材に対する膨潤効果が水より大きいアミン類 (n-ブチルアミン, エチレンジアミン, ホルムアミド, n-ブチルアミン-水混合物, エチレンジアミン-水混合物) による木材の体積膨潤と膨潤木材のRT-およびRL-方向の剛性の関係を検討した。水による膨潤に対してこれら膨潤剤による膨潤比は1. 2 - 1. 5の範囲で, せん断応カ-ヒズミ線図を比較すれば, 水で膨潤した木材に比べてアミン類で膨潤した木材では比例限度が不明確となり, 破壊までの平均剛性率が著しく低下する。X線回折の結果から, この平均剛性率の低下はセルロースのミセル内膨潤に基づくものではない。ミセル内膨潤を起こさない範囲でアミンによる木材の膨潤は同時に破壊ヒズミの増大をともなうが, アミンがセルロースのミセル内膨潤を起こす濃度以上となれば, 膨潤木材は比較的小さいヒズミで破壊に至る。

The swelling of wood in n-butylamine, ethylenediamine, formamide and some amine-water mixtures, and the torsional properties of the swollen wood have been determined for Hinoki (Chamaecyparis obtusa ENDL.) and Makanba (Betula maximowiczii REGEL) to obtain the fundamental knowledges about the plasticization of wood with swelling agents. Wood swells in n-butylamine, ethylenediamine and formamide 1.2 to 1.5 times the swollen volume in water (Table 1). The shearing stress-strain curves of the swollen wood show that these swelling agents diminish the elastic region and lower the average rigidity (Fig. 1 and 2, Table 2). A particular increase in the deformation has been observed for wood swollen in formamide. In both n-buthylamine- and ethylenediamine-water mixtures, the swelling of wood increases with increasing amine fraction in the mixtures (Fig. 4). Average rigidity of wood swollen with the 1:3 or amine-richer mixtures falls to one third of that of water swollen wood (Table 3). From X-ray studies of wood swollen with water, ethylenediamine, formamide and ethylenediamine-water mixture, it has been found that the intramicellar swelling of wood occurs as wood is treated with ethylenediamine and ethylenediamine-water mixture containing 65% or more amine (Fig. 7 and 9). These experimental facts suggest that the fall in average rigidity is not essentially due to the intramicellar swelling of cellulose. The maximum deformation of the swollen wood increases three to four times that of the non-swollen wood with increasing swelling within a limit of intermicellar swelling (Fig. 8).