SWELLING OF WOOD .2. SWELLING IN ORGANIC LIQUIDS

The rate and maximum swelling of several North American wood species i n 40 organic liquids have been obtained with a computer interface line ar variable displacement transformer. Since wood swells very fast in s ome organic liquids, even at room temperature, this apparatus made it possible to obtain accurate rate data on the swelling of wood in organ ic liquids. It was found that many similarities existed between wood a nd cellulose maximum swelling within various solvent chemical classes. Hence, it appears that cellulose is the primary wood polymer responsi ble for the major amount of swelling of wood. In general, all the liqu ids, with a molar volume greater than 100cc or with a small hydrogen b onding parameter, caused very little equilibrium swelling. The logrith m of the rate of wood swelling (lnk) in the liquids was inversely corr elated with the solvent molecular weight as well as with the molar vol ume of the solvent, that is, the larger the solvent molecular size, th e slower the rate of swelling. The lnk also was strongly correlated wi th the maxmium tangential swelling of wood. The maximum tangential swe lling for all wood species was linearly correlated with the solvent ba sicity (donor number). Other solvent properties such as solubility par ameter, dipole moment, dielectric constant, and surface tension showed very weak correlations with the maximum tangential swelling of wood i n organic liquids.