Effects of heat-treatment patterns on the collapse-shrinkage characteristics in plantation-grown Eucalyptus timber
Eucalyptus, widely planted in south China, is the most potential tree species used for high value-added solid wood products supplanting natural forest.However, collapse characteristics during heat-treatment process severely restrains its above-mentioned potenial.In order to explore the effects of heat-treatment patterns on the collapse-shrinkage characteristics, the total shrinkage and amount of collapse were measured by means of image analysis technique on wood from low-density plantation-grown eucalypt (Eucalyptus urophylla and E.grandi) and high-density ones (E.cloeziana and E.pellita) under continuous and intermittent heat-treatment conditions,respectively. The results showed that 1) with continuous heat-treatment temperature rising, the total shrinkage and collapse increase rapidly on low-density eucalypt, which was resulted from the instantaneous collapse in more wall-thickness fibre and parenchyma cells being transformed into the residual collapse,while slightly increase on high-density eucalypt,which may be brought on by only a few wall-thickness fibre cells and some parenchyma cells collapse occurring; 2) with intermittent heat-treatment temperature increasing, except the total shrinkage and collapse increasing slightly on high-density eucalypt, while the total shrinkage and collapse in low-density eucalypt decrease rapidly, the main reasons are that, on one hand, the more fibre cells participating in instantaneous collapse occurance are easier to be recovered,while the parenchyma cells being concerned with instantaneous collapse development are more difficult to be recovered, on the other hand, the instantaneous collapsed cells under high temperature may last the shorter time whenever reducing 10％ mc, it may be probable for the instantaneous collapsed wall-thickness fibre cells to be recovered and for the instantaneous collapsed parenchyma cells to be transformed into the residual collapse. Accordingly, we can draw a conclusion that the continuous heat-treatment pattern may be more suitably applied to high-density eucalypt wood,while intermittent heat-treatment pattern is fit for low-density eucalypt one.
Continuous heat treatment Intermittent heat treatment Total shrinkage Amount of collapse Instantaneous collapse Plantation-grown Eucalyptus
WU Yi-qiang HAYASHI Kazuo PENG Wan-xi LIU Yuan
College of Material Science and Engineering, Central South University of Forestry & Technology Chang Faculty of Agriculture, Ehime University, Matsyama, Japan,790-8566 College of Material Science and Engineering, Central South University of Forestry & Technology Chang
国际会议
郑州
英文
2007-10-23（万方平台首次上网日期，不代表论文的发表时间）