A Method for Studying Dynamic Sorption Behavior of Small Wood Samples

Abstract

A method for determining mass changes (∼ 0.0001 g) in small (∼ 4-mm cubes) wood samples using the resonance of small mechanical springs mounted on piezoelectric sensors is presented. The size of the sample allows individual heartwood or sapwood, earlywood, latewood, and compression wood samples to be measured in an oscillating relative humidity environment and compared in terms of time constant and moisture gain. Since the apparatus is cost effective, many replicates can be achieved in one experiment. The use of small wood samples such that all tracheids are exposed removes the effect of structure on bound water transport. This, in combination with the ability to measure the response to small perturbations in relative humidity, presents the possibility to determine gaseous diffusion coefficients as a function of moisture content for individual wood types.

Preliminary, representative results of a study comparing the effect of drying temperature on sorption behavior of wood dried at 20, 90, and 150°C are presented.

Keywords:

• Bound water diffusion
• Measurement of small mass changes
• Wood drying