棕榈藤(rattan)是热带森林中仅次于木材和竹材、 重要的非木材林产品, 具有很高的经济价值和开发前景。 由于目前对棕榈藤的细胞结构, 尤其是藤纤维的细胞壁结构知之甚少, 严重限制了对棕榈藤材的研究和加工利用。 因此, 为构建棕榈藤材纤维细胞壁结构模型、 探索棕榈藤强韧机理, 选择高地钩叶藤为研究对象, 采用X射线衍射法(XRD), 分别测量并计算藤纤维微纤丝角、 结晶度及微晶体尺寸等结晶参数; 其中微纤丝角计算选用0.4 T法。 微纤丝角测试时, 试样沿直径方向由一侧藤皮开始依次切取尺寸为 L(长)× T(厚)× W(宽)=25 mm×0.5 mm×W的试件8片, 然后放置在温度为(20±2)℃、 相对湿度为65%±5%的调温调湿箱中平衡处理至少一周。 结晶度及微晶体尺寸测试时, 每个试样再分藤皮、 藤中和藤芯三个部分, 使用球磨机磨成粉末后放入烘箱中在(103±2)℃下烘至绝干。 研究结果表明: 高地钩叶藤微纤丝角在22.53°~49.47°间变异, 平均值为36.50°。 径向上藤皮处微纤丝角最小, 藤芯处微纤丝角最大, 说明藤皮强度比藤芯好; 轴向上微纤丝角为2 m处>梢部>中部>基部, 微纤丝角与藤龄间规律性不强。 藤茎结晶度在21.40%~36.45%间变异, 平均值为29.99%。 径向上纤维素结晶度为藤皮>藤中>藤芯; 轴向向上随藤龄减小, 结晶度呈先升后降变化趋势, 且最大值在中部、 最小值在基部。 纤维素微晶体宽度在5.72~6.19 nm间变异, 平均值为6.03 nm。 藤皮处微晶体宽度最小, 藤芯最大; 藤茎平均微晶体宽度与藤中、 藤芯一样, 随着藤茎高度的升高呈先下降后至中部达最小值后又上升的变化趋势。 微晶体长度在13.07~19.34 nm间变异, 平均值为15.59 nm。 径向上微晶体长度为藤皮>藤芯>藤中; 微晶体长度轴向随着藤茎高度上升, 均呈“降—升—降”趋势, 总体上微晶体长度基部高于梢部, 呈下降趋势。 高地钩叶藤藤茎中段比基部和梢部材质好、 藤皮比藤芯质量高。

Rattan is an important non-timber forest product inferior to timber and bamboo, with high economic value and development prospects. But little is known about the cell structure of rattan, especially the cell wall structure of fiber at present, which seriously limits the research, processing and utilization of rattan. Therefore, in order to construct the fiber wall structure model and explore the toughness mechanism of rattan, Plectocomia himalayana was chosen as the research material, and X-ray diffraction (XRD) was used to calculate the microfibril angle (MFA), crystallinity and size of microcrystals, among them 0.4T method was used to calculate the MFA. In the MFA test, eight specimens with the size of L(long)× T(thick)× W(wide)=25 mm×0.5 mm× W were selected from one side of the cortex in turn along the diameter direction of the sample, and then placed in the Temperature and Humidity Control Box with the temperature of (20±2)℃ and the relative humidity of 65%±5% for at least one week. When measuring crystallinity and microcrystalline size, each sample was divided into the cortex, middle layer and core. After grounding into powder by Ball Mill, it was put into the Oven and dried to absolute drying at (103±2)℃. The results showed that: the MFA of P. himalayana varied from 22.53° to 49.47° with an average of 36.50°. The MFA was the smallest in the cortex and the largest in the core in radial, which indicated the strength of cortex was better than that of the core. The MFA was 2 m>the tip>the middle>the base in axial, and the regularity between the MFA and the rattan age was not obvious. The cellulose crystallinity varied from 21.40% to 36.45% with an average of 29.99%, and the cellulose crystallinity was the cortex>middle layer>core in radial. Axial upward, with the decrease of rattan age, the crystallinity increased first and then decreased and the maximum value was in the middle and the minimum value was at the base. The microcrystal width of cellulose varied from 5.72 to 6.19 nm with an average of 6.03 nm. The average width of microcrystals at cortex was the smallest and the core was the largest. Like the middle layer and core, the average width of microcrystals of rattan stem decreased first, then reached the minimum in the middle and then rose with the increase of the height. The microcrystal length varied from 13.07 nm to 19.34 nm with an average of 15.59 nm. The length of microcrystals was the cortex>core>middle layer in radial; the length of microcrystals showed a downward-upward-downward trend along with the increase of rattan height in axial, and the microcrystal length at the base was higher than that at the tip, showing a downward trend. The middle part of the stem is better than the base part and the tip part, and the cortex is better than the core.