毛竹材立杆高度对竹壁厚度、竹秆直径以及表面元素分布影响研究
The Study of the Effect of Bamboo Stem Height on Thickness, Diameter and Surface Element Distribution of Bamboo Stem

为系统了解竹材在高度方向的性能特点，本文以毛竹材(5年竹龄)为对象，研究了竹壁厚度(壁厚)、直径以及表面元素与立杆高度关系，结果表明：1) 随着立杆高度增加，竹材壁厚与直径均减小。当立杆高度小于1.20 m时，壁厚和直径与立杆高度分别存在高度相关的线性关系和二次函数关系；当立杆高度大于1.20 m时，壁厚和直径与立杆高度都是高度相关的一次线性关系，且单位高度的壁厚和直径降低量均小于高度小于1.2 m时的降低量；2) 基于竹材在高度方向的壁厚和直径分布特点而开发的梯形竹条，与常规矩形竹条相比，体积出材率和重量出材率分别提高11.30%与10.90%左右；3) 在竹材高度方向上，无论是竹黄(高度2.0 m除外)，竹青或者竹肉表面，碳、氧等元素含量分布相对比较均匀，说明立杆高度对元素含量分布影响比较小；4) 在竹材厚度方向，碳元素平均含量：竹青 > 竹黄 > 竹肉；氧元素平均含量：竹肉 > 竹黄 > 竹青；抽提物和灰分的平均含量：竹黄 > 竹肉 > 竹青。
The effect of bamboo stem height (5 years growth ages) on bamboo thickness, diameter and element distribution is studied to understand the property features in height directions systematically. The results indicate that (1) bamboo thickness and diameter decrease with increasing bamboo height and there exist critical height for bamboo stem, which is 1.20 m. When the stem height is less than critical heights, the relationships of bamboo thickness and diameter with heights are linear functions and quadratic functions respectively, and the reduction of stem thickness and diameter per meter in height direction is more than that when the stem height is more than critical heights with the relationships being both linear functions. In other words, when the stem height is lower than critical heights, the diameter and thickness tapering grade are more than that higher than critical heights; (2) the outturn ratios of T-strips according to volume and weight and are 11.3% and 10.9% higher than that of conventional rectangular strips; (3) the element distribution on the height directions is evenly; (4) the distribution laws of carbon ratio are: bamboo green bamboo yellow bamboo culm; the distribution laws of oxygen ratio are: bamboo culm bamboo yellow bamboo green; the distribution laws of extracts and ash are: bamboo yellow bamboo culm bamboo green.