Off-axis photoelasticity by anisotropic molecular deformation of uniaxially aligned cellulose nanofiber films
Off-axis photoelasticity by anisotropic molecular deformation of uniaxially aligned cellulose nanofiber films
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DOI：
10.1016/j.carpta.2021.100166
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发表时间：
2021-12
影响因子：
5.5
通讯作者：
K. Uetani;Takuya Uto
中科院分区：
文献类型：
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作者：
K. Uetani;Takuya Uto
我们报道了细菌纤维素纳米纤维（CNFs）单向排列膜的光弹性的角度依赖性，通过施加相对于CNF取向的0°-90°的离轴应力。当应力方向靠近CNF轴向时，光弹性系数为正，当应力方向靠近CNF横向时，光弹性系数为负。在玻璃纸薄膜的离轴光弹性和纤维二糖模型中两个原子之间拉伸的密度泛函理论（DFT）计算中也观察到正到负的光弹性。另一方面，与玻璃纸薄膜不同，CNF薄膜表现出5 ~−10 TPa−1的正、负不对称光弹性，反映了晶体模量张量的各向异性。我们发现纤维素晶体的存在或不存在通过限制分子变形来控制光弹性的各向异性。
We report the angle dependence of the photoelasticity for unidirectionally aligned films of bacterial cellulose nanofibers (CNFs) by applying the off-axis stress at 0°–90° with respect to the CNF orientation. The photoelastic coefficient was positive when the stress direction was close to the CNF axial direction, and it was negative when the stress was applied close to the lateral direction. The positive to negative photoelasticity was also observed in the off-axis photoelasticity of the cellophane film and in the density functional theory (DFT) calculations for the stretching between two atoms in the cellobiose model. On the other hand, unlike the cellophane film, the CNF film showed a positively and negatively asymmetric photoelasticity of 5 to −10 TPa−1, reflecting the anisotropy of the crystal modulus tensor. We found that the presence or absence of cellulose crystals controls the anisotropy of photoelasticity by constraining the molecular deformation.