Add a small amount of the graphene can significantly improve the strength of carbon fiber

Carbon fiber (in CFs) inorganic fiber is a high performance, and after the polymer, ceramic or metal composite material, prepared of a high strength, high stiffness, low density, corrosion and fatigue resistance of the composite material in the aerospace, automotive, military , sports and other areas have important uses, and therefore in the laboratory and industrial production, carbon fiber materials are the focus of the study. As another star of the carbon material graphene since the birth of concern. Wherein a large number of high strength polymer-based composites research showed that: Graphene has unique physicochemical properties can be the mechanical strength of the material at very low added amount condition improved significantly. Then the two-dimensional structure of microscopic graphene whether enhance the mechanical strength of the carbon fiber macro-one-dimensional structure of it?

[research]

Recently, the University of Virginia Xiaodong Li, Adri CT van Duin professor research team jointly Pennsylvania State University Leonid V. professor Zhigilei research team found that adding 0.075 wt% of mechanical exfoliation of graphene allows the carbon fiber tensile l strength and Young\’s modulus increased by 225% and 184%, respectively. By the results of the microstructure of various graphene content of the composite carbon fibers and macro-mechanical properties were characterized and analyzed, and the combination of computer simulation, the authors found that trace amounts of graphene from the following three factors to improve the mechanical strength of the carbon fibers:

( 1) graphene reduced hole inside carbon fiber / defect size, enhance its integrity; (2) graphene optimize the alignment of the carbon fiber precursor polyacrylonitrile (PAN) molecular chain fibers; (3) the graphene can be improved the mechanical strength of the carbon fiber body.

The research work only graphene mechanism of the carbon fibers is further explored, higher strength after, for the preparation of high modulus carbon fibers provide theoretical guidance; the same time, by adjusting the microstructure of the prepared high-performance carbon fibers research work provides a good idea. This research work paper entitled \”Graphene reinforced carbon fibers\” published in the \”Science Advances\”. (Link attached description) 添加少量石墨烯可大幅度提高碳纤维强度

[Photo A]

添加少量石墨烯可大幅度提高碳纤维强度
FIG. 1. (A).PAN / graphite fiber composite process ene; (B) – (G) are graphene content 0,0.01wt%, 0.025wt%, 0.05wt%, 0.075wt%, and 0.1wt% CF / graphene composite carbon fiber cross-section FIG SEM; (H) and (I) are different graphene content CF / graphene composite tensile strength of carbon fibers, the Young\’s modulus and elongation at break results

of the different levels of mechanical peeling dispersing the graphene in PAN / DMSO solution to give a PAN / graphene composite fibers by wet spinning; then subjected to preoxidation – carbonization – after high-temperature treatment to obtain graphitized CF / graphene composite carbon fiber. Tensile test results show that the addition of carbon fiber composite graphene small amount while maintaining elongation at break, can greatly improve the tensile strength of carbon fibers and a Young\’s modulus: The tensile strength of the original carbon fibers and Young\’s modulus were carbon fiber tensile strength and Young\’s modulus of 589 MPa and 82 GPa, was added 0.075 wt% graphene were 1916 MPa and 233 GPa, compared to the original carbon fibers were increased 225% and 184%. Microstructure of various composite carbon fiber test results showed that the introduction of the reduced graphene internal carbon fiber hole / defect size, increasing its integrity, FIG. 1 (B) – (D) shown in FIG.

添加少量石墨烯可大幅度提高碳纤维强度
Nano Figure 2. X-ray tomographic image different from a graphene content of the composite carbon fiber; NOTE: the figure indicates the portion of the orange fiber axial crack, the circled area represents the fiber longitudinal nanometric defects

added 0.1 wt% greater tacticity graphene composite carbon fibers, but the results show that the tensile strength and modulus of less than 0.075 wt% of a composite containing carbon fibers, which is why ? The nano X-ray tomographic image results, the authors found that although high levels of graphene fiber may help to improve the regularity and reduce axial crack fiber, but increase dramatically longitudinal spherical nanometric defects fiber, which reduces the mechanical strength of the fibers . To further explore the impact mechanism graphene carbon fiber mechanical properties of the whole preparation process of the composite carbon fibers were studied and analyzed, it was found: a small amount of the graphene increase viscosity PAN / DMSO solution, which may improve PAN fibers in a coagulation structured processOf reducing defects final carbon fibers; performs characterization of microstructure and mechanical tests after pre-oxidation, the PAN carbonized treated / graphene composite fibers, found fiber containing 0.075 wt% graphene in the various stages showed the highest mechanical strength and structural regularity. After processing the conjugate fiber graphitized TGA and XRD results show that addition of graphene can increase the amount of residual carbon fiber and carbon graphitization degree.

添加少量石墨烯可大幅度提高碳纤维强度
Figure 3. oxidized PAN fiber stage (blue) and PAN / graphene composite fiber (orange) simulation. (A) ~ (C) are two kinds of fibers N2, the amount of generation of H2 and H2O over time; (D) ~ (F) are the two kinds of fibers vary in 5,6,7-membered ring content over time ; (G) of the two fibers of the carbon content changes with time; (H) and (I) is represented by the structural fibers 6, 7 membered ring containing graphene schematic form

for the molecular the level of understanding of the impact on the carbon fiber structure of graphene, the authors conducted a simulation and molecular modeling. Simulation results show ReaxFF graphene unique reactivity –PAN edge may form a five-, six- and seven-membered carbocyclic ring graphene edges during the heat treatment; simultaneously added graphene also increases the six-membered ring and the regular arrangement of the residual carbon ratio. Molecular modeling results show that PAN graphene may cause localized rearrangement of molecular chains, so that the pitch of the molecular chain PAN reduced, which is advantageous in reducing defects in carbon fibers and enhance the crystallinity, thereby improving the mechanical properties of carbon fibers.

[summary]

The authors found that the introduction of small amounts of graphene can significantly improve the mechanical strength of the carbon fiber to PAN fiber precursor, and binding experiments and simulation results enhancement mechanism graphene further explored from a molecular point , it provides a theoretical basis for the future preparation of the carbon fiber material of high strength and low cost. Original link: https: //advances.sciencemag.org/content/6/17/eaaz4191

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