Superplasticity of CNT

The theoretical maximum tensile strain, or elongation, of a SWCNT is almost 20 % [48, 49], but in practice, only 6 % [50] has been achieved at room temperatures. However, at high temperatures (estimated at 2,000 K might be too high with respect to Ref. [24]), individual SWCNTs can undergo a superplastic deformation, becoming nearly 280 % longer and 15 times thinner, from 12 to 0.8 nm, before tensile failure [51]. 

The temperature in the middle of the SWCNT is more than 2,270 K as estimated during deformation at a bias of 2.3 V with a current flow. Despite the 

Such large plastic strains in nanotubes demonstrate their ductile namre at high temperatures [52-54], which concurs with BOLS predictions that the strain limit is exponentially proportional to the inverse of separation between the melting point and the temperature of operation. In contrast, tensile-pulling experiments at room temperature without any bias showed that almost all nanotubes failed at a tensile strain of less than 15 %. Superplasticity ofMWCNT could be possible in vacuum at elevated temperatures as the T for the MWCNT is higher than that for the SWCNT. 

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