Processing of Nanotubes Using Liquid Composite Molding Techniques

碳纳米管具有提高聚合物复合材料物理和力学性能的潜力。在过去的几年里，人们发明了各种方法来制备性能更好、成本更低的纯纳米管。纳米管广泛使用的两个主要障碍是(1)成本和(2)缺乏将纳米管分散在基质中而不形成团簇并影响其取向行为的加工技术。该项目将通过探索在玻璃纤维增强复合材料中加工纳米管以形成混杂纳米-微米复合材料的方法来解决这些问题。将聚合物树脂和碳纳米管悬浮液注射到玻璃纤维预制件中，将能够制造杂化纳米-微米聚合物复合材料。这些材料将比纯纳米复合材料便宜，因为使用的纳米管的体积分数将很小。改进纤维增强复合材料的现有工艺也可以降低纳米微米复合材料的制造成本。在这个项目中，将介绍三种广泛使用的液体复合模塑(LCM)工艺的创新改进，以制造复合材料和探索碳纳米管在纤维预制件中的流动诱导分散和取向行为。已经证明，纳米管的分散和取向可以由流变性作用或通过将纳米管悬浮液拉过多孔介质来诱导。新的工艺将使用这种概念，通过拉伸或剪切来拉伸承载纳米管的树脂的流动。这将有助于定性地了解纳米管的分散和取向行为与悬浮流动特性之间的关系。工作说明书分为三项主要任务：(1)含有纳米管的悬浮液的制备和表征(2)采用三种不同的改进LCM工艺加工混杂微纳米复合材料试件，其中纳米管和树脂被引入预置纤维预制件的模具中(3)微观结构的检查和与加工的关联以及机械性能的提高的测量。复合材料中心拥有进行这项研究的必要设备。长期目标是通过操纵树脂的剪切和拉伸来控制纳米管的分散和取向行为。其总体意图是使混杂纳米-微米复合材料成为可设计的材料，从而使碳纳米管和连续微纤维系统行业都受益。

Carbon nanotubes have exhibited the potential to enhance the physical and mechanical properties of polymer composites. In the past few years, various methods have been invented to produce pure nanotubes with enhanced properties and reduced cost. The two main barriers to the widespread use of nanotubes are (1) cost and (2) lack of processing techniques to disperse the nanotubes through the matrix without forming clusters and to influence their orientation behavior. This project will address these issues by exploring methods to process nanotubes in glass-fiber-reinforced composites to form hybrid nano-micro composites. Injection of the polymer resin and the carbon nanotubes suspension into glass-fiber performs will enable the manufacture of hybrid nano-micro polymeric composites. These materials will be less expensive than pure nano-composites, as the volume fraction of the nanotubes used will be small. Modifying existing processes for fiber-reinforced composites can also reduce the manufacturing cost of nano-micro composites. In this project, three innovative modifications of widely used Liquid Composite Molding (LCM) processes to manufacture composites and explore the flow-induced dispersion and orientation behavior of carbon nanotubes within fiber preforms will be introduced. It has been shown that dispersion and alignment of nanotubes can be induced by rheological actions or by drawing the nanotubes suspension through a porous medium. The new processes will use this concept of stretching the flow of the resin that carries the nanotubes by either elongation or shear. This will allow the development of qualitative understanding of the relationship between the dispersion and orientation behavior of the nanotubes and the suspension flow properties. The statement of work is divided into three main tasks; (1) preparation and characterization of the rheological properties of suspensions containing nanotubes (2) processing of hybrid micro nanocomposites specimens with three different modified LCM processes, where nanotubes and resins are introduced in a mold containing pre-placed fiber preforms (3) examination and correlation of the microstructure to processing and measurement of enhancement in mechanical properties. The Center for Composite Material has the necessary equipment to conduct the study.The long-range goal is to control the dispersion and the orientation behavior of the nanotubes by manipulating the shearing and stretching of the resin. The overall intent is to make hybrid nano-micro composites into designable materials that will benefit both the carbon-nanotubes and the continuous micro-fiber system industries.