木質材料 遠赤外線くん煙熱処理スギ材の材質特性

Abstract

Logs of Sugi (Cryptomeria japonica D. Don) were treated by a smoke-heating system with increased far-infrared radiation. Logs were smoke-heated for about 35 hours at a temperature inside the logs of more than 80°C. No damage was found in the logs by the treatment. After the treatment, the changes of some wood qualities (bending strength, shrinkage, swelling, degree of crystallinity, amounts of chemical components) were examined. The modulus of elasticity (MOE) in bending of sapwood increased about 13% by the treatment, whereas in heartwood almost no difference in bending strength between the smoke-heated and control logs was found. The degree of crystallinity increased about 8% in sapwood, almost corresponding to the increase ratio of MOE. The smoke-heated logs increased both their shrinkage and swelling in heartwood, but decreased both of them in sapwood. The results obtained here suggested almost no difference in wood qualities between the smoke-heated and control logs. This fact indicates that smoke-heating of logs did not causes any thermal deterioration in wood.