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林业科学 ›› 2019, Vol. 55 ›› Issue (7): 128-136.doi: 10.11707/j.1001-7488.20190714

• 论文与研究报告 • 上一篇    下一篇

基于纳米压痕技术的木材胶合界面力学行为

王新洲1, 谢序勤2, 王思群3, 李延军1, 梁星宇1   

  1. 1. 南京林业大学材料科学与工程学院 南京 210037;
    2. 德华兔宝宝装饰新材股份有限公司 德清 313200;
    3. 田纳西大学可再生碳中心 诺克斯维尔 37996
  • 收稿日期:2017-04-19 修回日期:2017-09-09 出版日期:2019-07-25 发布日期:2019-08-16
  • 基金资助:
    江苏省自然科学基金青年项目(BK20180774);国家自然科学基金面上项目(30871973);江苏省高等学校自然科学研究重大项目(17KJA220004)。

Investigation of the Mechanical Behavior of Wood-Adhesive Interphase by Using Nanoindentation

Wang Xinzhou1, Xie Xuqin2, Wang Siqun3, Li Yanjun1, Liang Xingyu1   

  1. 1. College of Materials Science and Engineering, Nanjing Forestry University Nanjing 210037;
    2. Dehua Tubaobao New Decoration Material Co., Ltd. Deqing 313200;
    3. Center for Renewable Carbon, University of Tennessee Knoxville 37996
  • Received:2017-04-19 Revised:2017-09-09 Online:2019-07-25 Published:2019-08-16

摘要: [目的]研究木材胶合界面的静态和动态力学行为,探讨树脂渗透对木材管胞壁层力学性能的影响,为木质复合材料制造工艺优化和增强改性提供理论依据。[方法]采用纳米压痕静态和动态力学测试技术(Nano-DMA),对针叶材火炬松与酚醛树脂(PF)、脲醛树脂(UF)胶黏剂所形成胶合界面区域各相材料的静态弹性模量、硬度、蠕变性能以及储能模量和损耗模量等力学行为进行分析。[结果]静态力学行为方面,在界面区域,PF和UF渗透进入管胞壁层后,木材管胞壁的弹性模量(Er)和硬度(H)提高;经PF渗透后,木材管胞壁的ErH分别增加7%和26%;Burgers蠕变力学模型可有效描述胶合界面区域管胞壁的纳米压痕蠕变特性,经树脂渗透后,木材管胞壁的瞬时弹性模量增加,黏弹性模量和黏性系数减小;在保载初期,PF界面区域木材管胞壁的蠕变柔量约下降60%,UF界面区域木材管胞壁的蠕变柔量约下降58%。动态力学行为方面,随着加载频率增加,界面材料的储能模量(E'r)逐渐增大,而损耗模量(Er)和损耗因子(tanδ)呈减小趋势;当加载频率为10 Hz时,PF和UF树脂渗透使得管胞壁层的储能模量分别增加16%和29%。[结论]胶合界面区域胶黏剂进入管胞壁层,对木材管胞的静态力学性能具有增强作用,同时胶黏剂可提高管胞壁的短期抗蠕变能力;木材管胞壁具有较高的储能模量和损耗模量,而树脂的储能模量和损耗模量较低,经树脂渗透后,木材管胞壁的储能模量增加,但损耗模量和损耗因子呈下降趋势,可能对界面传递和分散应力产生不利影响。

关键词: 木材, 胶合界面, 管胞壁, 力学, 纳米压痕

Abstract: [Objective] The effects of the penetration of resin on the mechanical properties of wood cell wall in the interphase region were studied systematically, which provided the theoretical basis for the optimization of the manufacturing technology and the enhancement modification of wood-based composites.[Method] The elastic modulus, hardness, creep properties, dynamic storage modulus, and dynamic loss modulus of wood cell walls from loblolly pine (Pinus taeda)and resins (phenolic resin and urea-formaldehyde resin)in the interphase region were investigated by the means of nanoindentation and nanoscale dynamic mechanical analysis (Nano-DMA).[Result] In the static mechanical behavior, the effective penetration of resin contributed greatly to the elastic modulus (Er)and hardness (H)of cell wall of wood tracheid in the interphase region. In the interphase of wood-PF, the elastic modulus (Er)and hardness (H)of loblolly pine cell wall increased by 7% and 26%, respectively. The curve fitting goodness of fit (coefficient of determination squared value R2)was greater than 0.97, indicating Burgers model can be used to describe the mechanical indentation creep characteristics of wood tracheid cell walls. The instant elastic modulus of the wood cell wall in the interphase increased, while the viscoelastic modulus and the viscosity decreased after being penetrated with resin. In the initial period of load holding, the creep compliance of the wood cell wall decreased by about 60% and 58% after being penetrated by PF resin (phenolic resin)and UF resin (urea-formaldehyde resin), respectively, as compared to the control cell wall. In the dynamic mechanical behavior, with the increase of the loading frequency, the storage modulus E'r of the interphase increased gradually, while the loss modulus Er and loss tangent tan δ decreased. When the loading frequency was 10 Hz, the storage modulus of the cell wall layer of wood tracheid penetrated with PF resin and UF resin increased by about 16% and 29%, respectively.[Conclusion] The penetration of resins made a great contribution to the elastic modulus, hardness, and short-term creep resistance of wood cell wall. The important dynamic mechanical parameters obtained by Nano-DMA indicated that wood cell wall had a higher storage modulus and loss modulus as compared to that of the adhesives. The storage modulus of the cell wall penetrated with adhesive had an increase in comparison to the control cell wall, while the loss modulus and loss tangent showed a decreasing tendency, which will have negative effect on stress transfer and dispersion in the interphase region of wood-based composite.

Key words: wood, interphase, cell wall layer of tracheid, mechanical behavior, nanoindentation

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