Effect of end-taping and removal of sapwood on radial distribution of moisture content and tangential strains during radio-frequency/vacuum drying of Cedrela sinsensis log cross sections

Abstract

This study was carried out to investigate the effects of end-taping of sapwood (ETS) and removal of sapwood (ROS) treatments of log cross sections on the radial distributions of moisture content (MC) and tangential strain, according to the circumferential slicing method (CSM), during radio-frequency/vacuum (RF/V) drying of log cross sections. The MC of control and ETS samples showed an even distribution around the center but decreased closer to the periphery side. In ROS samples, the MC decreased closer to the periphery side when above the hygroscopic range but showed an even distribution at the late stage of drying. Tangential strain in ETS samples showed slight compressive stress or tensile stress through the entire area of the cross section during the initial stage of drying, although the periphery side was in tensile stress from an area starting at a relative radius of 0.7. ROS samples showed tensile stress in the heartwood around the center and the heartwood of the periphery side and showed no stress or slight compressive stress in the middle area at the initial stage of drying, after which it showed an even distribution of tensile stress throughout the entire end surface. About 90% of the total checks contained in ETS and ROS samples were observed on the periphery side starting from a relative radius of 0.7.