Optimization of the mechanical performance of bacterial cellulose/poly(L-lactic) acid composites.
Optimization of the mechanical performance of bacterial cellulose/poly(L-lactic) acid composites.
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DOI：
10.1021/am900817f
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发表时间：
2010
影响因子：
9.5
通讯作者：
F. Quero;M. Nogi;H. Yano;K. Abdulsalami;S. Holmes;B. Sakakini;S. Eichhorn
中科院分区：
文献类型：
--
作者：
F. Quero;M. Nogi;H. Yano;K. Abdulsalami;S. Holmes;B. Sakakini;S. Eichhorn
了解复合材料中纳米纤维和聚合物树脂之间界面的性质具有挑战性，因为纤维之间以及基体与纤维之间可能发生相互作用的复杂性。能够选择最有效的应力传递增强材料数量，从而节省成本和重量，也是复合材料设计的关键部分。首次报道了使用拉曼光谱研究层压细菌纤维素（BC）/聚（L-乳酸）酸（PLLA）树脂复合材料的微机械性能，作为了解这些复合材料中基本应力传递过程的手段，同时也作为选择适当的加工和增强纤维体积分数的工具。研究了两种形式的 BC 网络，即一种培养 3 天，另一种培养 6 天。发现后者的机械性能在杨氏模量、失效应力和断裂功方面高于前者。然而，发现它们的比杨氏模量（除以密度）是相似的。研究发现，对于体积分数为 18% 的 BC 纤维，透明的非晶态 PLLA 薄膜的杨氏模量和失效应力分别增加了 100% 和 315%。通过氮吸附测量，与培养 6 天的材料相比，培养 3 天的 BC 网络表现出与 PLLA 的相互作用增强，因为其总表面积更高。这种增强的相互作用通过使用拉曼光谱方法得到证实，由此观察到最初位于 1095 cm(-1) 处的峰相对于应变和应力的较大带位移率，这是增强应力传递的定量测量。样品的热分析（差示扫描量热法）和电子显微镜成像（扫描电子显微镜）也证实了与培养 6 天的树脂和培养 3 天的 BC 网络相比，树脂和 BC 网络之间的耦合增强。这些结果对使用BC网络进行复合增强材料具有影响，从而可以使用更少的材料来获得相同的特定机械性能。该技术还提供了详细研究这些复合材料中的界面的机会。
Understanding the nature of the interface between nanofibers and polymer resins in composite materials is challenging because of the complexity of interactions that may occur between fibers and between the matrix and the fibers. The ability to select the most efficient amount of reinforcement for stress transfer, making a saving on both cost and weight, is also a key part of composite design. The use of Raman spectroscopy to investigate micromechanical properties of laminated bacterial cellulose (BC)/poly(l-lactic) acid (PLLA) resin composites is reported for the first time as a means for understanding the fundamental stress-transfer processes in these composites, but also as a tool to select appropriate processing and volume fraction of the reinforcing fibers. Two forms of BC networks are investigated, namely, one cultured for 3 days and another for 6 days. The mechanical properties of the latter were found to be higher than the former in terms of Young's modulus, stress at failure, and work of fracture. However, their specific Young's moduli (divided by density) were found to be similar. Young's modulus and stress at failure of transparent predominantly amorphous PLLA films were found to increase by 100 and 315%, respectively, for an 18% volume fraction of BC fibers. BC networks cultured for 3 days were shown to exhibit enhanced interaction with PLLA because of their higher total surface area compared, as measured by nitrogen adsorption, to the material cultured for 6 days. This enhanced interaction is confirmed by using the Raman spectroscopic approach, whereby larger band shift rates, of a peak initially located at 1095 cm(-1), with respect to both strain and stress, are observed, which is a quantitative measure of enhanced stress transfer. Thermal analysis (differential scanning calorimetry) and electron microscopy imaging (scanning electron microscopy) of the samples also confirms the enhanced coupling between the resin and the BC networks cultured for 3 days, compared to those cultured for 6 days. These results are shown to have implications for the use of BC networks for composite reinforcement, whereby less material can be used for the same specific mechanical properties. The technique also gives opportunities to study the interfaces in these composite materials in detail.