Properties and Structure of Nitric Acid Oxidized Single Wall Carbon Nanotube Films

Single wall carbon nanotube films (bucky paper ) have been prepared using aqueous dispersions containing 0, 3, 6, and 10 M nitric acid. With increasing nitric acid concentration, film tensile strength increased from 10 to 74 MPa, tensile modulus from 0.8 to 5.0 GPa, while in-plane dc electrical conductivity decreased from 3 × 10 4 S/m to 1.2 × 10 4 S/m. In-plane storage modulus exhibited no decrease in the measured temperature range (room temperature to 200 °C). Raman spectroscopy showed that nitric acid treatment results in the loss of the small diameter tubes. This was consistent with the X-ray diffraction observation, which showed that with increasing nitric acid concentration, (10) and (11) SWNT d spacings increased from 1.23 to 1.29 nm and from 0.74 to 0.87 nm, respectively. Morphological changes in the film have been monitored using scanning electron microscopy.