4种竹材微纤丝角变异及其对抗弯性质的影响

采用X线衍射技术研究4种常见经济型竹种撑篙竹、粉单竹、吊丝竹、青皮竹的微纤丝角变异以及撑篙竹材质生成过程中微纤丝角（MFA）在纵向和径向位置的变化趋势，并探讨微纤丝角对竹材抗弯强度（MOR）和抗弯弹性模量（MOE）影响。4种3年生竹材的平均微纤丝角由大到小顺序为粉单竹＞吊丝竹＞撑篙竹＞青皮竹，分别为10.46°、9.73°、9.66°和9.52°，竹种间的微纤丝角差异甚微，变化范围在0.53°～1.48°；在径向上，撑篙竹与其他3种竹材微纤丝角从内侧到外侧到竹黄均呈增加趋势。方差分析表明，径向部位对微纤丝角有显著性影响。撑篙竹微纤丝角受竹龄影响不显著，随竹龄的增加呈现先增加后降低的趋势；在纵向上，不同竹龄的微纤丝角沿竹秆高度方向变化趋势不尽相同，受纵向部位影响显著。微纤丝角对4种竹材的抗弯性质都有一定程度的影响，只有粉单竹的抗弯强度和抗弯弹性模量与微纤丝角的相关性比较显著。研究结果以期为竹林培育和竹材合理加工利用提供理论依据。

Variation of Microfibril Angle of Four Bamboo Species and Its Effect on Bending Properties

The variations of the microfibril angle (MFA) of 4 bamboo species with high economic value were studied by the X-ray diffraction technology,including Bambusa pervariabilis (1-,2-,3-year-old) and B.chungii,B.textilis and Derdrocalamns minor (3-year-old).The longitudinal and radial variations of MFA in developmental B.pervariabilis were analyzed and compared with other three bamboo species.The influence of MFA on the bending strength (MOR) and modulus of elasticity (MOE) of bamboo was discussed.Bamboo blocks were cut from the middle of internode.MFA was measured by a Powder X-ray diffraction (XRD) from Panalytical in Netherlands.The determination of the mechanical properties of bamboo referred to the national standard GB/T15780-95，“Test method for physical and mechanical properties of bamboo”.The average MFA of 4 bamboo species was in the order (from large to small) of B.chungii＞D.minor＞B.pervariabilis＞B.textilis with the correspongidng values of 10.46°,9.73°,9.66°,and 9.52°,respectively.Small differences presented in MFA among 4 bamboo species,and the variation ranged from 0.53° to 1.48°.There existed an increasing tendency in MFA from the inner to the periphery of bamboo culms for B.pervariabilis and other 3 bamboo species.MFA of B.pervariabilis increased,then decreased with bamboo age.Longitudinal variations of MFA in B.pervariabilis took irregular pattern with different ages.Variance analysis indicated that the radial position and longitudinal position had a significant effect on MFA,but not the bamboo age.The mechanical properties of 4 bamboo species were all influenced by MFA,in which MOR and MOE in B.chungii with MFA showed a strong positive correlation.The results of this paper will provide a theoretical basis for bamboo plantation and the rational processing and utilization of bamboo.