Mechanical and Aerospace Engineering, University of Florida, PO Box 116250, Gainesville, Florida 32611-6250, United States.
ACS Appl Mater Interfaces. 2013 Feb;5(3):635-45. doi: 10.1021/am302060v. Epub 2013 Jan 17.
Low interface strength is a persistent problem in composite materials and cascades to limit a variety of bulk material properties such as lamina shear strength. Whiskerization has long been pursued as a method to reinforce the interphase and improve both the single fiber interface strength as well as the bulk properties. Recent developments have shown that ZnO nanowire whiskerization can effectively improve the properties of a bulk composite without requiring the high temperatures that previous deposition processes needed. Although the efficacy of a ZnO nanowire interphase has been established, the mechanism for adhesion of the interphase to the fiber has not been identified. Specifically, the addition of the ZnO nanowires to the surface of the fibers requires that the ZnO nanowires have strong chemical adhesion to the fiber surface. This work will create a variety of chemical environments on the surface of the fibers through new and common chemical functionalization procedures and quantify the surface chemistry through X-ray photoelectron spectroscopy. The effect of fiber surface chemistry on the adhesion of the ZnO is assessed through single fiber fragmentation testing. The interface strength is found to strongly correlate with the concentration of ketone groups on the surface of the fibers. Following the experimental observations, liftoff of a ZnO crystal from a graphene surface was simulated with a variety of surface functionalizations. The computational models confirm the preference for ketone groups in promoting adhesion between ZnO and graphite.
界面强度低是复合材料的一个长期存在的问题，这限制了各种块状材料性能的发展，例如层间剪切强度。晶须化一直以来都被作为一种增强相间的方法，以提高单纤维界面强度和块状材料性能。最近的研究表明，氧化锌纳米线晶须化可以在不需要以前沉积工艺所需的高温的情况下，有效地改善块状复合材料的性能。尽管已经证实了氧化锌纳米线相间层的功效，但相间层与纤维的附着机制尚未确定。具体来说，要将氧化锌纳米线添加到纤维表面，就需要纳米线与纤维表面具有很强的化学附着力。本工作将通过新的和常见的化学功能化程序在纤维表面上创建各种化学环境，并通过 X 射线光电子能谱法对表面化学进行量化。通过单纤维断裂试验评估纤维表面化学对氧化锌附着的影响。研究发现，界面强度与纤维表面上酮基的浓度强烈相关。在实验观察之后，通过各种表面功能化对氧化锌晶体从石墨烯表面的脱离进行了模拟。计算模型证实了酮基在促进 ZnO 和石墨之间的附着方面的偏好。
