SWELLING OF WOOD .1. SWELLING IN WATER

The rate and maximum swelling of several North American wood species i n water have been obtained with a computer interfaced linear variable displacement transformer. Since wood swells extremely fast in water ev en at room temperature, this apparatus made it possible for the first time, to obtain accurate rate data on the swelling of wood in water. T he strict linear dependence of swelling on the temperature suggests a chemical mechanism. The activation energies obtained from Arrhenius pl ots ranged from 32.2 KJ/mole for sitka spruce to 47.6 KJ/mole for suga r maple. Although the two hardwoods exhibited greater maximum tangenti al swelling compared with the two softwoods, the maximum swelling appe ars to be correlated with the wood density. Generally both the rate an d maximum swelling of the woods were increased by removal of extractiv es and the activation energies were reduced.