Particle alignment effects on mechanical properties of cellulose nanocrystal thin films
Particle alignment effects on mechanical properties of cellulose nanocrystal thin films
复制标题
颗粒排列对纤维素纳米晶薄膜力学性能的影响
DOI：
10.1039/d2ma00870j
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发表时间：
2023
影响因子：
5
通讯作者：
Davis, Chelsea Simone
中科院分区：
文献类型：
--
作者：
Son, Hyeyoung;Smith, Dawson Michael;Li, Zhaofan;Chang, Taehoo;Xia, Wenjie;Davis, Chelsea Simone
由于其各向异性的力学性能，纤维素纳米晶薄膜作为可持续材料越来越受到人们的关注。以前的计算工作已经表明，CNC膜的断裂机制随颗粒相对于加载方向的排列而变化。然而，由于超薄数控薄膜的脆性，在实验上测量其机械各向异性是一项具有挑战性的工作。在这里，开发了一种新的实验方法，在观察断裂机制的同时，确定数控对准对弹性模量的影响。在这种方法中，将单轴拉伸应变施加到层叠在有机硅衬底上的数控薄膜上，并将机械工作台安装在显微镜上。在机械测试过程中，通过测量在低应变下垂直于拉伸应变方向形成的皱纹的波长来计算出的模数。随着颗粒与加载方向偏移量的增加，CNC膜的弹性模量呈指数衰减。通过进行粗晶模拟，比较错位角和断裂应变以外的裂纹张开方向，观察到错位对断裂机制的影响。
Cellulose nanocrystal (CNC) thin films are of increasing interest as sustainable materials due to their anisotropic mechanical properties. Previous computational work has shown that the fracture mechanisms of CNC films vary as a function of particle alignment with respect to the loading direction. However, it is challenging to experimentally measure the mechanical anisotropy of extremely thin CNC films due to their brittleness. Here, a new experimental approach was developed to identify the effect of CNC alignment on modulus while simultaneously observing the fracture mechanisms. In this method, uniaxial tensile strain is applied to a CNC film laminated on a silicone substrate with a mechanical stage mounted over a microscope. The modulus calculated by measuring the wavelength of wrinkles that formed perpendicular to the tensile strain direction at low strains during mechanical testing. The elastic modulus of CNC films decayed exponentially as the misalignment of particles to the loading direction increased. By carrying out coarse-grained modeling and comparing the misalignment angle with the crack opening direction beyond the fracture strains, fracture mechanism dependence on misalignment was observed.