We apply immense strain to ultralong, suspended, single-walled carbon nanotubes while monitoring their Raman spectra. We can achieve strains up to 13.7 ± 0.3% without slippage, breakage, or defect formation based on the observation of reversible change in Raman spectra. This is more than twice that of previous observations. The rate of G band downshift with strain is found to span a wide range from −6.2 to −23.6 cm−1/% strain. Under these immense strains, the G band is observed to downshift by up to 157 cm−1 (from 1592 to 1435 cm−1). Interestingly, under these significant lattice distortions, we observe no detectable D band Raman intensity. Also, we do not observe any broadening of the G band line width until a threshold downshift of ΔωG > 75 cm−1 is achieved at high strains, beyond which the fwhm of the G band increases sharply and reversibly. On the basis of a theoretical nonlinear stress−strain response, we estimate the maximum applied stress of the nanotubes in this study to be 99 GPa with a strength-to-weight ratio of almost 74000 kN·m/kg, which is 30 times that of Kevlar and 117 times that of steel.
Eurekalert – the scientists applied immense tension to individual carbon nanotubes of different lengths and widths. They found that nanotubes could be stretched up to 14 percent of their normal length without breaking, or more than twice that of previous reports by others.
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