Cellulose Nanocrystals vs. Cellulose Nanofibrils: A Comparative Study on Their Microstructures and Effects as Polymer Reinforcing Agents
Cellulose Nanocrystals vs. Cellulose Nanofibrils: A Comparative Study on Their Microstructures and Effects as Polymer Reinforcing Agents
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DOI：
10.1021/am302624t
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发表时间：
2013-04-24
影响因子：
9.5
通讯作者：
Wiesenborn, Dennis P.
中科院分区：
文献类型：
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作者：
Xu, Xuezhu;Liu, Fei;Wiesenborn, Dennis P.
纤维素纳米晶体（CNCs）和纤维素纳米纤丝（CNFs）都是纳米级纤维素纤维，在聚合物纳米复合材料中显示出增强作用。CNCs和CNF在形状、大小和组成上不同。本研究系统地比较了它们的形态、晶体结构、在聚氧化乙烯（PEO）基体中的分散性能、与基体的相互作用以及由此产生的对基体聚合物的增强作用。通过溶液浇铸获得包含至多10重量%纳米纤维的透明PEO/CNC和PEO/CNF纳米复合材料。采用扫描电子显微镜（SEM）、广角X射线衍射（WXRD）、透射电子显微镜（TEM）、傅里叶变换红外光谱（FTIR）、动态力学分析仪（DMA）和拉伸测试等方法对纳米纤维素纤维及其复合材料的上述性能进行了研究。在相同的纳米纤维素浓度下，由于CNF较大的长径比和纤维缠结，CNF导致比CNC更高的强度和模量，但由于其相对较大的纤维团聚体，导致更低的断裂应变。采用Halpin-Kardos和Ouali模型对复合材料的弹性模量进行了模拟，模拟结果与实验值吻合较好。这种类型的系统的比较研究，可以帮助开发的标准，选择合适的纳米纤维素作为生物基纳米增强材料的聚合物纳米复合材料。
Both cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) are nanoscale cellulose fibers that have shown reinforcing effects in polymer nanocomposites. CNCs and CNFs are different in shape, size and composition. This study systematically compared their morphologies, crystalline structure, dispersion properties in polyethylene oxide (PEO) matrix, interactions with matrix, and the resulting reinforcing effects on the matrix polymer. Transparent PEO/CNC and PEO/CNF nanocomposites comprising up to 10 wt % nanofibers were obtained via solution casting. Scanning electron microscopy (SEM), wide-angle X-ray diffraction (WXRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), dynamic mechanical analyzer (DMA), and tensile testing were used to examine the above-mentioned properties of nanocellulose fibers and composites. At the same nanocellulose concentration, CNFs led to higher strength and modulus than did CNCs due to CNFs' larger aspect ratio and fiber entanglement, but lower strain-at-failure because of their relatively large fiber agglomerates. The Halpin-Kardos and Ouali models were used to simulate the modulus of the composites and good agreements were found between the predicted and experimental values. This type of systematic comparative study can help to develop the criteria for selecting proper nanocellulose as a biobased nano-reinforcement material in polymer nanocomposites.