The drying defects，such as splits，checks and collapses，are developed during the drying of Eucalyptus urophylla×E.grandis. In order to improve the dried wood quality by reducing those drying defects，the reasons that caused the collapse was explored. The effect of two pretreatments，i.e.，microwave and freezing，on wood permeability，drying rate and characteristics of collapse，were investigated. The results indicated that the permeability was more or less increased，the drying rate was raised and the collapse was reduced by using these treatments. On the control and microwave treated wood，it was observed that the crumples or wrinkles took place on borders of heartwood and sapwood. It was also seen that some wood fibers were twisted and squashed each other，their pit chambers were narrowed and the twist bands which vicinity squashed and collapsed in opposite directions were formed. The width of the twist band included 5—20 cells and the depth of the collapse was 0.76 mm on the control wood. While the width of the twist band included 5—10 cells and the depth of the collapse was 0.35 mm on the microwave treated wood. No considerable collapses were found and twist bands with a width of 1—2 cells were observed vaguely on the freezing treated wood.
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
References
[1]刘元.热处理对桉材皱缩的作用[J].林业科学,1994,30(2):140-144.
[2]江泽慧，费本华，王喜明，等.桉树木材干燥特性与工艺及其皱缩研究现状[J]. 木材工业,2002,16 (4):3-6.
[3]王欣,王喜明,蒙景军.干燥工艺条件对预冻处理皱缩特性的影响[J].内蒙古农业大学学报，2000,21(1):95-98.
[4]王喜明，王军，刘晓丽. 木材皱缩评价指标的研究[J]. 林业科学，2000，36（3）：130-132.
[5]王喜明，刘晓丽，薛振华，等. 预冻处理减少木材皱缩的研究[J]. 林业科学，2003，39（5）：96-99.
[6]陈太安，顾炼百. 汽蒸处理回复赤桉干燥皱缩的研究[J].南京林业大学学报：自然科学版，2004，28（3）：34-36.
[7]郭明辉，勾锐.木材皱缩的研究现状及发展趋势[J].世界林业研究，2005，18（1）：39-42.
[8]苗平，张耀丽，庄寿增，等.尾巨桉木材的渗透性对皱缩的影响[J].南京林业大学学报：自然科学版，2010，34（5）：83-86.
[9]江泽慧，王喜明.桉树人工林木材干燥与皱缩[M].北京：中国林业出版社，2003.
[10]王喜明．木材皱缩[M]．北京：中国林业出版社，2003.
[11]Choong E T.Collapse and moisture flow in kilndrying and freezedrying of woods[J]. Wood Science，1973,6(2):127-135.
[12]Yany J L. Anattempt to reduce collapse through introducing cell wall deformations[J]. Wood and Fiber Science，1998,30 (1):81-89.
[13]Chafe S C. The distribution and interrelationships of collapse，volumetric shrinkage，moisture content and density in tress of Eucalyptus regnans F.Muell[J]. Wood Sci Tech，1985,19(4):329-345.
[14]Innes T C. Collapse and internal checking in the latewood of Eucalyptus regnans F. Muell[J]. Wood Sci Tech,1996，30(6): 373-383.
[15]John F Siau. Wood: Influence of moisture on physical properties[R].Virginia： Polytechnic Institute and State University，1995.
[16]王喜明，薛振华，石丽慧，等.微波改性木材的初步研究[J]. 木材工业，2002,16（6）：16-19
PDF(1903926 KB)
