Ultrahigh strength and modulus of polyimide-carbon nanotube based carbon and graphitic fibers with superior electrical and thermal conductivities for advanced composite applications

• Published in: Composites. Part B, Engineering Vol. 247; p. 110342
• Main Authors: Kim, Seo Gyun, Heo, So Jeong, Kim, Sungyong, Kim, Junghwan, Kim, Sang One, Lee, Dongju, Lee, Suhun, Kim, Jungwon, You, Nam-Ho, Kim, Minkook, Kim, Hwan Chul, Chae, Han Gi, Ku, Bon-Cheol
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2022
• Subjects: Carbon fibers; Carbon nanotubes; Carbon-fiber-reinforced polymer composites; Mechanical properties; Polyimide; Carbon nanotubes; Mechanical properties; Polyimide; Carbon fibers; Carbon-fiber-reinforced polymer composites
• ISSN: 1359-8368; 1879-1069
• DOI: 10.1016/j.compositesb.2022.110342

Development of carbon fibers (CFs) with high strength and high modulus for structural applications in CF-reinforced polymer (CFRP) industry has been a challenge. Herein, we propose a method for manufacturing highly oriented polymer–carbon nanotube (CNT) composite fibers having high strength (4.8 ± 0.2 GPa), modulus (390 ± 48 GPa), and electrical conductivity (5.75 ± 0.84 MS m-1) by a liquid crystalline wet-spinning process. The use of chlorosulfonic acid (CSA) as a solvent for CNTs and polyimide (PI) promotes dispersion and enables the production of high-performance composite fibers. In addition, the functional groups of PI in composite fibers improve the interfacial shear strength with epoxy resin without sizing additives by 72% compared to that of CNT fibers. Carbonization and graphitization of the composite fibers with an optimal ratio of PI (30%) and CNT cause significant improvement in their mechanical (tensile strength; 6.21 ± 0.3 GPa and modulus; 701 ± 47 GPa) and thermal properties (496 ± 38 W m−1 K−1) by reducing voids and improving orientation. We believe that the polymer–CNT composites and their CFs with high strength and high modulus would be the next-generation CFs for aerospace and defense industry. [Display omitted] •PI-CNT composite fibers with high strength and modulus applicable to CFRPs were fabricated by wet-spinning using CSA.•Interfacial shear strength between PI–CNT composite fiber and epoxy resin increased up to 72% compared with that of CNT fiber.•Optimal content ratio of PI and CNT in composite fibers induce the improvement of orientation and reduced internal voids.•Carbonization of fibers leads to significant improvement of tensile strength (6.21 ± 0.3 GPa) and modulus (528 ± 26 GPa).