Processing of Nanotubes Using Liquid Composite Molding Techniques

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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.