Influence of transverse compression on axial electromechanical properties of carbon nanotube fibers

Abstract

Axial electromechanical properties after transverse compression of carbon nanotube (CNT) fibers were studied for their potential application in constructing lightweight structures. The structure-property relationship under two different compression modes was revealed due to their unique mechanical and electrical properties. Change of disentanglements and slippage between CNTs or CNT bundles during transverse compression significantly altered the axial tensile performance. The axial tensile strength of aerogel-spun and dry-spun CNT fibers increased by 20.6% and 11.9 % under individually compressed at 60 MPa and 90 MPa, respectively. The tensile moduli of both fibers increased by 0.05 GPa. Followed by reduction of tensile performance as compressive strain level increased. The corresponding electrical resistance of both deformed CNT fibers increased more rapidly than that of the uncompressed fibers. In the cyclic compression mode, the axial tensile strength and modulus decreased by 40% and 45.7% for the aerogel-spun CNT fibers and by 17% and 14.2% for dry-spun CNT fibers owing to permanent damage accumulation. Scanning electron microscope examinations showed that tensile failure mode after compression transitioned from slippage into a new mode based on the fracture of CNT bundles. The failure mechanisms were finally investigated by a theoretical model. Keywords: CNT fiber, Axial electromechanical properties, Transverse compression, Cyclic loading-unloading