Multiwall Carbon Nanotube Reinforcement of Polyacrylonitrile Fibers

Aligning multiwall carbon nanotubes (MWNTs) with the direction of load is desirable for maximizing tensile reinforcement in composites. This has been accomplished by spinning composite fibers containing MWNTs[1]. The shear and elongational flow fields inherent to fiber processing cause the MWNTs to align with the fiber axis. Efficient stress transfer from the matrix to the MWNTs is also a crucial component for maximizing reinforcement. In an effort to address both of these issues, this paper reports the use of functionalized MWNTs as aligned reinforcing nano-fibers in a polyacrylonitrile (PAN) fiber matrix with the goal of producing carbon/MWNT composite fiber with enhanced physical properties. A variety of chemical vapor deposition derived MWNTs have been previously evaluated as reinforcement including: as-produced MWNTs (used as harvested from the reactor substrate) and graphitized MWNTs (heat treated to 2800°C under flowing He)[1], but recent emphasis has been placed on improving the interfacial adhesion of the PAN matrix to the embedded MWNTs through chemical modification of the MWNT surface. Investigation is focused on the use of methacrylate functionalized MWNTs which have been copolymerized with acrylonitrile (mispMWNTs) as reinforcement in PAN/MWNT composite fiber.