Endowed with excellent mechanical properties, cellulose nanopaper provides a promising design strategy for addressing the dilemma between the strength and toughness of engineering materials. Anisotropic nanopaper with highly aligned nanofibers can achieve high mechanical properties. In this paper, we develop a multiscale tension-shear model that correlates both the strength and toughness with the microstructure to quantitatively understand the exceptional properties of anisotropic cellulose nanopaper. By formulating a relationship between the interfacial macroscopic performance and nanoscale parameters involving the self-healing of hydrogen bonds, we establish a microstructure-based constitutive model of cellulose nanopaper to describe its nonlinear mechanical behavior. It is theoretically suggested that engineering the nanofiber size enables cellulose nanopaper to realize strengthening and toughening. Meanwhile, multiple mechanical properties of the nanopaper can be simultaneously enhanced by increasing the hydrogen bond density. A scaling relation is proposed to correlate the mechanical properties of cellulose nanopaper with the microstructure parameters. The developed model predictions agree well with the relevant experimental data. The constitutive model can also be extended to describe the mechanical response of cellulose bulk materials. This work can not only help understand the fundamental deformation mechanisms of cellulose nanopaper, but also help design high-performance nanocellulose structural materials.

具有出色的机械性能，纤维素纳米纸为解决工程材料的强度和韧性之间的难题提供了一种有前途的设计策略。具有高度排列的纳米纤维的各向异性纳米纸可以实现高机械性能。在本文中，我们开发了一种多尺度的拉伸剪切模型，该模型将强度和韧性与微观结构相关联，以定量地了解各向异性纤维素纳米纸的优异性能。通过制定界面宏观性能与涉及氢键自我修复的纳米级参数之间的关系，我们建立了基于微结构的纤维素纳米纸本构模型，以描述其非线性力学行为。从理论上讲，对纳米纤维尺寸进行工程处理可使纤维素纳米纸实现增强和增韧。同时，可以通过增加氢键密度同时增强纳米纸的多种机械性能。提出了比例关系以使纤维素纳米纸的机械性能与微观结构参数相关。所开发的模型预测与相关实验数据非常吻合。本构模型也可以扩展为描述纤维素散装材料的机械响应。这项工作不仅可以帮助理解纤维素纳米纸的基本变形机理，而且可以帮助设计高性能的纳米纤维素结构材料。可以通过增加氢键密度同时增强纳米纸的多种机械性能。提出了比例关系以使纤维素纳米纸的机械性能与微观结构参数相关。所开发的模型预测与相关实验数据非常吻合。本构模型也可以扩展为描述纤维素散装材料的机械响应。这项工作不仅可以帮助理解纤维素纳米纸的基本变形机理，而且可以帮助设计高性能的纳米纤维素结构材料。可以通过增加氢键密度同时增强纳米纸的多种机械性能。提出了比例关系以使纤维素纳米纸的机械性能与微观结构参数相关。所开发的模型预测与相关实验数据非常吻合。本构模型也可以扩展为描述纤维素散装材料的机械响应。这项工作不仅可以帮助理解纤维素纳米纸的基本变形机理，而且可以帮助设计高性能的纳米纤维素结构材料。所开发的模型预测与相关实验数据非常吻合。本构模型也可以扩展为描述纤维素散装材料的机械响应。这项工作不仅可以帮助理解纤维素纳米纸的基本变形机理，而且可以帮助设计高性能的纳米纤维素结构材料。所开发的模型预测与相关实验数据非常吻合。本构模型也可以扩展为描述纤维素散装材料的机械响应。这项工作不仅可以帮助理解纤维素纳米纸的基本变形机理，而且可以帮助设计高性能的纳米纤维素结构材料。