Mechanical and electrical properties of carbon nanotube ribbons Yan-Hui Li a, * , Jinquan Wei a , Xianfeng Zhang a , Cailu Xu a , Dehai Wu a , Li Lu b , Bingqing Wei c a Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China b Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China c Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA Received 31 July 2002; in final form 7 September 2002 Abstract WehavemeasuredtheYoungÕsmodulusoflongalignedcarbonnanotuberibbonsusingaspecialstress–strainpuller designed for whisker-like materials. The YoungÕsmodulusofthegraphitizedcarbonnanotuberibbonsisabout60GPa, which is 2.5 times higher than that of the as-grown ribbons. This suggests that the graphitization is an effective way to improve the mechanical properties of the ribbons. Most of the measured ribbons are semiconductor and their resis- tivities are in the range of 4.4–12:6  10 4 X cm. An interesting phenomenon appeared in one ribbon is that the electrical property of the ribbon changes from metallic to non-metallic with decreasing the temperature. Ó 2002 Elsevier Science B.V. All rights reserved. 1. Introduction Carbon nanotubes (CNTs) have been predicted topossessexceptionalmechanical[1–4]andunique electrical properties [5], which could have great potential applications as structural and intellectual materials. But too small individual CNTs make it difficultfurtherexploittheirvariouspropertiesand applications, it has been the dream and challenge to prepare long CNTs or their macrostructures. Rinzler et al. [6] first prepared bucky paper con- sisted of a free-standing mat of entangled single- wall CNTs and estimated their elastic modulus of 1.2 GPa [7]. Pan et al. [8] prepared very long aligned multiwalled CNTs and measured their YoungÕs moduli and the tensile strength to be 0:45  0:23TPaand1:72  0:64 GPa, respectively. Recently, Vigolo et al. [9] fabricated macroscopic fibers and ribbons of oriented CNTs through in- jecting nanotube dispersions into a flowing stream of polyvinylalcohol solution. The YoungÕs modu- lus of the fibers varied between 9 and 15 GPa. Electrical properties of the CNTs are another fascinating research field. They can be either me- tallic, non-metallic or insulating, depending on their diameter and chirality. Many efforts have been devoted to study the electrical properties of Chemical Physics Letters 365 (2002) 95–100 www.elsevier.com/locate/cplett * Corresponding author. Fax: +8601062782413. E-mail address: liyanhui99@mails.tsinghua.edu.cn (Y.-H. Li). 0009-2614/02/$ - see front matter Ó 2002 Elsevier Science B.V. All rights reserved. PII:S0009-2614(02)01434-3