欢迎访问林业科学,今天是

林业科学 ›› 2018, Vol. 54 ›› Issue (1): 174-180.doi: 10.11707/j.1001-7488.20180120

• 研究简报 • 上一篇    

不同生长期毛竹材细胞壁力学性能与微纤丝角

刘苍伟1, 苏明垒1, 王思群2, 王新洲3, 赵荣军1, 任海青1, 王玉荣1   

  1. 1. 中国林业科学研究院木材工业研究所 北京 100091;
    2. 田纳西大学可再生碳中心 诺克斯维尔 37996;
    3. 南京林业大学材料科学与工程学院 南京 210037
  • 收稿日期:2016-07-25 修回日期:2017-03-09 出版日期:2018-01-25 发布日期:2018-03-01
  • 基金资助:
    国家自然科学基金面上项目(31370562,31370563);浙江省林业工程重中之重一级学科开放基金(2014lygcz005)。

Cell Wall Mechanical Properties and Microfibril Angle of Phyllostachys edulis in Different Growth Period

Liu Cangwei1, Su Minglei1, Wang Siqun2, Wang Xinzhou3, Zhao Rongjun1, Ren Haiqing1, Wang Yurong1   

  1. 1. Research Institute of Wood Industry, CAF Beijing 100091;
    2. Center for Renewable Carbon, University of Tennessee, Knoxville 37996;
    3. School of Materials Science and Engineering, Nanjing Forestry University Nanjing 210037
  • Received:2016-07-25 Revised:2017-03-09 Online:2018-01-25 Published:2018-03-01

摘要: [目的]以不同生长期的毛竹材纤维细胞壁为研究重点,在纳米尺度下分别表征不同竹龄毛竹材纤维细胞壁的结构特征和力学性能,阐明成熟毛竹材纤维细胞壁的结构特征和力学性能与幼龄竹和过熟竹的差异,为竹材的科学采伐和竹材分级、改性及重组研究与合理利用提供理论依据。[方法]采用滑走显微制片法观察毛竹材横切面显微结构并精准确定其纳米压痕测试部位,应用纳米压痕技术结合非包埋制样法对0.5年幼龄毛竹、4.5年成熟毛竹和10.5年过熟毛竹材纤维细胞壁力学性能进行研究;利用广角X-射线散射法结合高斯拟合算法对不同竹龄毛竹材纤维细胞壁的微纤丝角进行测算。[结果]毛竹材竹肉横切面显微结构表明,毛竹主要由薄壁组织细胞和维管束组成,维管束由导管和包裹着导管周围的厚壁纤维细胞组成;对其厚壁纤维细胞壁的纳米压痕测试结果表明,3个生长发育期的毛竹材细胞壁力学性能指标有较大不同,其中0.5年幼龄毛竹材的细胞壁弹性模量和硬度最小,分别为10.7 GPa和0.358 GPa,4.5年成熟毛竹材的细胞壁弹性模量和硬度均为最大,分别为19.6 GPa和0.498 GPa,10.5年过熟毛竹材的细胞壁硬度和弹性模量居二者之间,分别为17.6 GPa和0.445 GPa;微纤丝角测试结果同样表明不同生长发育期毛竹材细胞壁的微纤丝角不同,其中0.5年幼龄毛竹材微纤丝角最大,为13.5°,4.5年成熟毛竹材微纤丝角度最小,为8.43°,而10.5年过熟毛竹材微纤丝角介于二者之间,为11.9°。[结论]生长期对毛竹材纤维细胞壁力学性能和微纤丝排列均有影响,幼龄毛竹材纤维细胞壁力学性能与成熟毛竹材纤维细胞壁力学性能有较大差别,随着竹龄增大达到成熟期时,毛竹材纤维细胞壁力学性能达到最大,但毛竹材并不是生长期越长其细胞壁力学性能越好,而是随着竹材老化其力学性能呈下降状态。处于成熟期的毛竹材其纤维细胞壁微纤丝排列与主轴的夹角呈较小状态,也决定了其具有较优的力学性能。依据3个竹龄毛竹材纤维细胞壁力学性能和微纤丝角测量结果,本研究在细胞壁水平阐明了毛竹材在成熟期时其微观力学性能优于幼龄毛竹材和过熟毛竹材。

关键词: 毛竹, 生长期, 细胞壁力学性能, 微纤丝角

Abstract: [Objective] Bamboo age is a key factor for logging and utilization of bamboo, and hence we focused on the fiber cell wall of different growth period. The characteristic and mechanical performance of fiber cell wall of moso bamboo aged 0.5 a, 4.5 a, and 10.5 a were investigated to find out the differences of characteristic and mechanical performance among immature, mature and overmature moso bamboo at nano-scale, which provided a new theoretical basis for the research of scientific logging, classification, modification and reorganization and rational utilization of bamboo in the future.[Method] The sections made by microtome and ultramicrotome were used to observe microstructure of the cross-section and then choose the precise area for nanoindentation experiments. Nanoindentation experiment combined with non-embedding method was used to investigate the mechanical properties of fiber cell wall, and the wide-angle X-ray scattering method with the Gaussian quasi legitimate calculation was applied to obtain the value of micrfibiril angle of moso bamboo.[Result] The observation of cross-section indicated that the parenchyma cells and vascular bundles were the main components of moso bamboo, and the vascular bundle was consisted of the vessel and thick walled fiber cells that surrounded the vessels. The mechanical properties of moso bamboo fiber exhibated significant differences among different growth period. The nanoindentation result showed that the mechanical properties of immature moso bamboo fiber cell wall were lower than those of mature and overimature moso bamboo. The value of elastic modulus and hardness were 10.7 GPa and 0.358 GPa, respectively. The mature moso bamboo showed the highest elastic modulus and hardness, 19.6 GPa and 0.489 GPa. The elastic modulus and hardness of overmature moso bamboo were 17.6 GPa and 0.445 GPa,respectively. The microfibril angle tests indicated that they were diverse among bamboos in different growth period. The mean microfibril angle of 0.5 a immature moso bamboo with 13.5° is higher than the others, and the 4.5 a mature moso bamboo with 8.43° is lowest, while the miscrofibril angle of 10.5 a overmature moso bamboo is 11.9°.[Conclusion] Based on the result it was concluded that the growth period have an influence on the fiber cell wall mechanical properties and microfibril angle of moso bamboo. The micromechanical properties showed apparent differences between the immature and mature moso bamboo, it was enhanced with bamboo age and achieved optimal micromechanical performances at mature, however, the reduced elastic modulus and hardness slightly decreased with bamboo age after the maturity. The angle between the microfibril arrangements and cell axis was least when the moso bamboo was mature, which account for its better mechanical properties. As a consequently, this study illustrates the micromechanical properties of the 4-5 years old moso bamboo was better than that of the immature and overmature moso bamboo at cell wall level.

Key words: Phyllostachys edulis, growth period, cell wall mechanical properties, microfibril angle

中图分类号: