Effects of Drying Schedules on Physical and Mechanical Properties in Paulownia Wood

Abstract

The effects of six drying schedules on physical and mechanical properties of Paulownia wood (Paulownia fortune Seem.) were studied. Three schedules were based on the recommendations by Forest Product Laboratory (FPL), while the other three were established based on diffusion theory. FPL schedules consisted of a mild (T₆E₃), a moderate (T₆E₄), and a severe (T₇E₄) drying schedule; diffusion schedules consisted of three initial moisture contents (MC) of 113% (Dif-1), 75.5% (Dif-2), and 53.5% (Dif-3). Boards with a commercial thickness of 5 cm were randomly dried to the final moisture content of 8 ± 2% in all six schedules. Results indicated that drying under diffusion schedules had the most improved properties due to the beneficial effect of heat upon wood plasticity. However, lower plasticity effect in FPL schedules, due to lower temperatures, resulted in lower properties in most cases.

Keywords:

• Diffusion
• Drying schedule
• Fast-growing wood species
• Forest product laboratory recommendations (FPL)
• Kiln drying
• Mechanical properties

ACKNOWLEDGMENTS

The authors are grateful to Dr. Reza Oladi (specialist in the biology of fast-growing species) and members of the academic staff at the University of Tehran for their great help in analyzing and interpretation of the results, as well as the microscopic image analyzing.