Mechanical properties of poplar wood (Populus alba) dried by three kiln drying schedules

Abstract

The influence of three drying schedules on the selected mechanical properties of poplar wood (Populus alba L.) was evaluated in terms of suitability for structural applications. For this purpose, 70 mm-thick poplar lumber was conventionally dried by three different moisture content based schedules of T 5-D 2, T 5-D 4, and T 5-D 6. In these schedules, the wet bulb depression was changed as a means of increasing of the drying intensity. After drying, the mechanical properties of the lumber, including bending properties (MOE and MOR), toughness, shear strength parallel to grain, and tensile strength perpendicular to grain, were measured. Results revealed that the severe drying schedule (T 5-D 6) caused higher reductions in the mechanical properties of the dried boards, particularly the MOE and MOR. Furthermore, toughness and tensile strength perpendicular to grain were not affected by the increasing of the wet bulb depression. The influence of all the three adopted schedules on the mechanical properties was evaluated using the drying rate, final moisture content gradient, and qualitative characteristics of the dried boards.