| 概要 |
この研究では,比重および組織･構造と電気伝導とのかかわりを明らかにする目的で,北海道産広葉樹20樹種の電気伝導率を,①細胞壁の量にかかわる因子,②木材構成要素の量および形態にかかわる因子と関係づけて検討した.含水率が一定のとき,電気伝導率と電気伝導率への含水率の影響は,細胞壁量や構成要素が木材中に占める体積割合との間に明確な相関関係を認めることができず,樹種の相違によって大きな変動を認めた.一方,...単位体積当りの含有水分量(水分リテンション)が一定のとき,細胞壁量と電気伝導率との間には高い相関関係が認められた.さらに水分リテンションが変化することによる電気伝導率の変化にも,細胞壁量が敏感に関与していることを明らかにした.したがって,含水率が同じでも樹種の相違によって電気伝導率が異なる原因は,同一含水率でも比重が異なれば水分リテンションに変化を生じ,さらに水分の存在状態にも変化を生じるためであると推定した.また,細胞壁の電気伝導率には樹種によっても変動を認めた.すなわち,樹種が異なることによる電気伝導率の相違は,細胞の形態や細胞壁構造にも関係していることを考慮すべきであろう.これらの考察結果は,組織･構造と水分リテンションとの関係が十分に明らかになれば,電気伝導率が木材細胞壁量にかかわる因子を有効に評価するための指標となることを示唆している.
The conductivities of 20 hardwood species were studied in relation to the quantitative indices of cell wall and of the elements constituting hardwood, in order to investigate a principle of variation in electrical conductivity among species and also to examine if it is possible to use electrical conductivity as an index of specific gravity. The conductivity at a given moisture content and the effect of moisture content on conductivity had large variation among species in those relationships to the quantitative indices of cell wall and elements. On the other hand, if the concentration of moisture per unit volume of wood (moisture retention) was constant, high correlations between the conductivity and the indices such as basic density and cell wall percentage were obtained. It was apparent that conductivity change with moisture retention was also highly correlated to the indices. Therefore it was assumed that the conductivity variation at a given moisture content was mainly caused by the difference of moisture retention with specific gravity and also by the quality change of adsorbed water with moisture retention among species. The intra-structure of cell wall and the cell dimension may be also important factors in the conductivity difference among species, because the conductivity of cell wall itself was shown to have the variation among species. The results suggested that, if the relationship between moisture retention and wood structure was sufficiently realized and more data were accumulated, electrical conductivity could be a reasonable index for specific gravity as well as for moisture content.続きを見る
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