【作者】 孟庆华； 李博； 冯西桥；

【Author】 Qinghua Meng;Bo Li;Xi-Qiao Feng;Institute of Biomechanics and Medical Engineering, Department of Engineering Mechanics, Tsinghua University;

【机构】 清华大学工程力学系生物力学与医学工程研究所；

【摘要】 纤维素纳米纸是一种可再生的生物纳米材料,具有优越的力学性能和广阔的应用前景。它的出现为解决工程材料强度和韧性之间的矛盾提供了新的设计策略。其力学行为的研究,可以揭示其微观结构与力学性能之间的关系,能够为其工程应用提供重要的参考。因此,本文提出了裂纹桥联模型来描述纤维素纳米纸的桥联增韧机理及其断裂韧性与微观结构之间的关系,并详细地讨论了纳米纤维的尺寸效应对纤维素纳米纸断裂韧性的影响。结果表明纳米纤维的桥联增韧机理对纤维素纳米纸的力学性能起到了重要的作用。增大纳米纤维的长度或减小纤维的半径都能够有效地提高纤维素纳米纸的断裂韧性。为了使纤维素纳米纸取得最佳的增韧效果,给出了纳米纤维的最优几何尺寸范围。本文不仅阐明了纤维素纳米纸的潜在增韧机理,而且能够为其他先进功能材料的设计和优化提供一定的借鉴。更多还原

【Abstract】 Cellulose nanopaper is a renewable biological nanomaterial, which has superior mechanical properties and potential applications. Its emergence provides a new design strategy for addressing the conflict between strength and toughness of engineering materials. Analyzing the mechanical behavior to reveal the relations between its microstructure and mechanical properties provides an important guide for engineering application. To this end,a crack-bridging model is proposed to reveal the bridging-toughening mechanism of cellulose nanopaper and correlate its fracture toughness with microstructure. The effects of nanofiber size on the fracture toughness of cellulose nanopaper are discussed in detail. It is found that the bridging-toughening mechanism of nanofibers plays a vital role in mechanical properties of cellulose nanopaper. Increasing the length of nanofibers or decreasing their radius can effectively enhance the fracture toughness of cellulose nanopaper. An optimal nanofiber geometry is suggested to achieve a high toughening effect of cellulose nanopaper. This work not only sheds light on the underlying toughening mechanisms of cellulose nanopaper, but also provides guidelines for the design and optimization of other advanced functional materials.更多还原