Oriented and exfoliated single wall carbon nanotubes in polyacrylonitrile

Polyacrylonitrile (PAN)/single wall carbon nanotubes (SWNT) fibers were gel spun at 0, 0.5, and 1 wt% SWNT content to a draw ratio of 51. Structure, morphology, and mechanical and dynamic mechanical properties of these fibers have been studied. PAN/SWNT composite exhibited much higher electron beam radiation resistance than PAN. As a result, PAN lattice images could be easily observed in the composite fiber by high resolution transmission electron microscopy. The PAN/SWNT composite fiber also exhibited higher solvent resistance than the control PAN fiber. UV-vis spectroscopy of highly drawn fiber exhibited van Hove transitions, suggesting SWNT exfoliation upon drawing. SWNT exfoliation was also confirmed by high resolution transmission electron microscopy (HRTEM). At 1 wt% SWNT loading, fiber storage modulus (at 1 Hz) increased by 13.9, 6.6, and 0.2 GPa at −75, 25, and 150 °C, respectively. This suggests that the load transfer ability and hence interfacial strength is increasing with decreasing temperature, even below the polymer's γ transition temperature.