The total heat of wetting in water has been determined calorimetrically on extractive-free wood (red pine and beech) as well as on the major components derived from it. The major components used for the present tests were; holocellulose, α-cellulose, hemicelluloses, lignin-carbohydrate complex, and lignin. Especially, acetyl glucomannan and acetyl glucuronoxylan were used in order to get informations on the native state of hemicellulose in wood.
The results obtained are as follows:
(1) The total heat of wetting of extractive-free red pine and beech wood in water are 20.49 cal/g and 19.67cal/g, respectively.
(2) The total heat of wetting of α-cellulose is almost the same as those of the wood.
(3) Of the materials tested, hemicelluloses had the highest total heat of wetting; acetyl glucomannan: 26.80cal/g, arabinoglucuronoxylan: 30.18cal/g and acetyl glucuronoxylan: 24.42cal/g.
(4) The total heat of wetting of lignin is markedly affected by the method used for the preparation of samples. The values for lignin such as milled wood lignin and alcohol lignin, are lower than those of the other major components. The value for Klason lignin is somewhat larger than those for lignin mentioned above.
(5) From these results it is possible to estimate the relative contributions of its three major components to the total heat of wetting of wood. The proportion of contributions of the three components to the total heat of wetting of extractive-free red pine wood is 0.43 for cellulose, 0.38 for hemicelluloses and 0.19 for lignin. Also the values for beech wood are 0.36, 0.48 and 0.16, respectively.
