Unsteady-State Diffusion of Moisture In Giant Timber Bamboo (Phyllostachys Bambusoides Sieb. & Zucc.)
Keywords:Diffusion, Fick's law, activation energy, bamboo
This paper presents the results of a study to determine the rate of moisture movement in giant timber bamboo (Phyllostachys bambusoides Sieb. & Zucc.) when exposed to three different temperatures (20 C, 30 C, and 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 and the weight-time data were analyzed using the Boltzmann solution to the unsteady-state form of Fick's diffusion equation.
Diffusion coefficients ranged from 7.3 x 10~12 to 7.8 x 10~11 m2/sec. They were greater at the higher moisture content range. They increased with temperature such that the Arrhenius equation fits the data well, giving mean activation energies of 39,875 and 35,889 J/mole for the lower and higher moisture ranges, respectively. The calculated diffusion coefficient was approximately twice as high during desorption as during adsorption.
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