Abstract In this study, micro-defects on/in carbon fibers were modified by irradiation with an electron beam, which improved the mechanical strength of single carbon fibers. The electron beam irradiation was 10 kGy (using a 1.5 MeV accelerator in the air). The total doses ranged from 100 to 500 kGy. The tensile strength of the single carbon fiber was measured using a universal testing machine. The micro-defects on the fiber surface were observed with scanning electron microscopy and atomic force microscopy, and those in the fiber were evaluated by Raman spectroscopy. In conclusion, the electron beam treatment produced changes in the micro-defects on/in the carbon fibers, resulting in up to 14% improvement in the tensile strength of single carbon fiber.

    Abstract
    1 Introduction
    2 Experimental
        2.1 Materials and electron beam irradiation
        2.2 Surface analysis
        2.3 Mechanical strength analysis
        2.4 Micro-structure analysis
        2.5 Composition analysis of the carbon fiber surface
    3 Results and discussion
        3.1 Changes in carbon fiber surface
        3.2 Mechanical properties of the carbon fibers
        3.3 Microstructure and elemental analysis
    4 Conclusion
    Acknowledgements 
    References

• Jin‑Soo Jeong(R&D Division, Korea Carbon Industry Promotion Agency)
• Kwan‑Woo Kim(R&D Division, Korea Carbon Industry Promotion Agency)
• Dong Chul Chung(Department of Organic Materials and Fiber Engineering, Chonbuk National University)
• Kay‑Hyeok An(Department of Carbon and Nano Materials Engineering, Jeonju University)
• Byung‑Joo Kim(Department of Carbon and Nano Materials Engineering, Jeonju University)