title: Extraordinary improvement of the graphitic structure of continuous carbon nanofibers templated with double wall carbon nanotubes.
abstract: Carbon nanotubes are being widely studied as a reinforcing element in high-performance composites and fibers at high volume fractions. However, problems with nanotube processing, alignment, and non-optimal stress transfer between the nanotubes and surrounding matrix have so far prevented full utilization of their superb mechanical properties in composites. Here, we present an alternative use of carbon nanotubes, at a very small concentration, as a templating agent for the formation of graphitic structure in fibers. Continuous carbon nanofibers (CNF) were manufactured by electrospinning from polyacrylonitrile (PAN) with 1.2% of double wall nanotubes (DWNT). Nanofibers were oxidized and carbonized at temperatures from 600 °C to 1850 °C. Structural analyses revealed significant improvements in graphitic structure and crystal orientation in the templated CNFs, with the largest improvements observed at lower carbonization temperatures. In situ pull-out experiments showed good interfacial bonding between the DWNT bundles and the surrounding templated carbon matrix. Molecular Dynamics (MD) simulations of templated carbonization confirmed oriented graphitic growth and provided insight into mechanisms of carbonization initiation. The obtained results indicate that global templating of the graphitic structure in fine CNFs can be achieved at very small concentrations of well-dispersed DWNTs. The outcomes reveal a simple and inexpensive route to manufacture continuous CNFs with improved structure and properties for a variety of mechanical and functional applications. The demonstrated improvement of graphitic order at low carbonization temperatures in the absence of stretch shows potential as a promising new manufacturing technology for next generation carbon fibers.
authors.affiliation: Department of Mechanical and Materials Engineering, Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0526, USA.
authors.forename: Dimitry
authors.initials: D
authors.lastname: Papkov
authors.forename: Allison M
authors.initials: AM
authors.lastname: Beese
authors.forename: Alexander
authors.initials: A
authors.lastname: Goponenko
authors.forename: Yan
authors.initials: Y
authors.lastname: Zou
authors.forename: Mohammad
authors.initials: M
authors.lastname: Naraghi
authors.forename: Horacio D
authors.initials: HD
authors.lastname: Espinosa
authors.forename: Biswajit
authors.initials: B
authors.lastname: Saha
authors.forename: George C
authors.initials: GC
authors.lastname: Schatz
authors.forename: Alexander
authors.initials: A
authors.lastname: Moravsky
authors.forename: Raouf
authors.initials: R
authors.lastname: Loutfy
authors.forename: Sonbinh T
authors.initials: ST
authors.lastname: Nguyen
authors.forename: Yuris
authors.initials: Y
authors.lastname: Dzenis
mesh_terms: D003460:Crystallization / Q000379:methods*; D006108:Graphite / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013499:Surface Properties; D013696:Temperature
chemical_list: D046911:Macromolecular Substances; D037742:Nanotubes, Carbon; D006108:Graphite