竹束去青程度对竹束单板层积材物理力学性能的影响

Effect of Removing Bamboo Green on Physical and Mechanical Properties of Laminated Bamboo-bundle Veneer Lumber

采用通过帚化技术去青后的慈竹竹束单板,制备了28 mm厚的竹束单板层积材,探讨了竹束去青程度对竹束单板层积材的尺寸稳定性、静曲强度、弹性模量和水平剪切强度的影响。研究结果表明:随竹束去青程度的提高,竹束表面的明度L*呈上升趋势,红绿轴色度指数a*和黄蓝轴色度指数b*增加,色差ΔE*增大;竹束去青程度越高,竹束表面的静态接触角越小,对应制得的竹束单板层积材的尺寸稳定性越好,干态静曲强度、弹性模量和水平剪切强度变化不大或稍有减小,但经过28 h处理后的强度均表现出更小的削减;不去青对竹束单板层积材强度降低的影响是最大的;针对水平剪切强度,A、B、C、D组板材均符合GB/T 20241—2006《单板层积材》标准要求,A、B、C组达到《重组竹》(报批稿)规定的9V-12H级别。

We employed the process of removing bamboo green and bamboo brooming , and produced Neosinocalamus affinis into laminated bamboo-bundle veneer lumber （ BLVL） with the thickness of28 mm.We studied the effect of removing bamboo green upon BLVL in dimensional stability , modulus of rupture （ MOR ） , modulus of elasticity （ MOE ） and horizontal shearing strength .The lightness （ L＊） was in a rising trend with increasing degree of removed bamboo green , and the red hue （ a＊） , yellow hue （ b＊） and aberration （ΔE＊） were enlarged .The higher degree of removed bamboo green was , the smaller contact angle of bamboo-bundle was obtained , and the better dimensional stability of corresponding BLVL was .As the degree of bamboo green removal increased , BLVL exhibited a slight decreasing value in modulus of rupture , modulus of elasticity and horizontal shearing strength before 28 hours’ treatment, while less strength reduction after 28 hours’ treat-ment .The ones without removal of bamboo green suffered most severe strength reduction .For horizontal shearing strength , A, B, C, and D veneer lumber could meet the standard requirement of GB /T 20241-2006 , and A, B and C, except for D, could reach the 9V-12H level of Bamboo scrimber standard.