UNSTEADY-STATE DIFFUSION OF MOISTURE IN GIANT TIMBER BAMBOO (PHYLLOSTACHYS BAMBUSOIDES SIEB AND ZUCC)

This paper presents the results of a study to determine the rate of mo isture movement in giant timber bamboo (Phyllostachys bambusoides Sieb . & Zucc.) when exposed to three different temperatures (20 C, 30 C, a nd 40 C) at two ranges of moisture content (0 to 7.5%, and 7.5 to 15%) . Edge-coated samples measuring 6 mm (R) x 30 mm(T) x 150 mm (L) were exposed to a given temperature-humidity combination in a conditioning chamber. The weight of a sample was continuously monitored over time a nd the weight-time data were analyzed using the Boltzmann solution to the unsteady-state form of Fick's diffusion equation. Diffusion coeffi cients ranged from 7.3 x 10(-12) to 7.8 x 10(-11) m(2)/sec. They were greater at the higher moisture content range. They increased with temp erature such that the Arrhenius equation fits the data well, giving me an activation energies of 39,875 and 35,889 J/mole for the lower and h igher moisture ranges, respectively. The calculated diffusion coeffici ent was approximately twice as high during desorption as during adsorp tion.