In response to the urgent need for sustainable and environmentally friendly materials, this study focuses on enhancing the flame retardancy and mechanical properties of epoxy composites using eco-friendly, non-halogen flame-retardant hybrid fillers. These fillers are synthesized from tannic acid (TA) and upcycled carbon black derived from waste tires (WT-CB) via a mechano-fusion process. The resulting TA/WT-CB fillers exhibit a core–shell structure, with WT-CB uniformly coating the TA surface, significantly improving flame retardancy compared to TA alone. When incorporated into epoxy resin, the TA/WT-CB fillers not only enhance flame resistance but also improve the composite’s mechanical properties. Optimal performance was observed at a filler content of 5 wt.%, where the composite demonstrated superior flame retardancy and mechanical strength. This innovative approach not only addresses fire safety concerns but also promotes sustainability by utilizing upcycled waste materials, offering a promising solution for environmentally conscious flame-retardant technologies.

Eco-friendly flame-retardant epoxy composite using tannic acid and upcycled carbon black via mechano-fusion
    Abstract
    1 Introduction
    2 Experimental
        2.1 Synthesis of TAWT-CBs
        2.2 Preparation of flame-retardant epoxy composites
        2.3 Characterization
    3 Results and discussion
        3.1 Characterization of flame-retardant hybrid filler (TAWT-CBs)
        3.2 Mechanical properties of epoxy composites containing TAWT-CB
        3.3 Flame-retardant properties of epoxy composites containing TAWT-CB
    4 Conclusion
    Acknowledgements 
    References

• Young Nam Kim(RAMP Convergence Research Center, Korea Institute of Science and Technology (KIST), 92 Chudong‑Ro, Bongdong‑Eup, Wanju‑Gun, Jeonbuk 55324, Republic of Korea)
• Chetna Tewari(RAMP Convergence Research Center, Korea Institute of Science and Technology (KIST), 92 Chudong‑Ro, Bongdong‑Eup, Wanju‑Gun, Jeonbuk 55324, Republic of Korea)
• Hyunsung Jeong(RAMP Convergence Research Center, Korea Institute of Science and Technology (KIST), 92 Chudong‑Ro, Bongdong‑Eup, Wanju‑Gun, Jeonbuk 55324, Republic of Korea)
• Somi Yoon(RAMP Convergence Research Center, Korea Institute of Science and Technology (KIST), 92 Chudong‑Ro, Bongdong‑Eup, Wanju‑Gun, Jeonbuk 55324, Republic of Korea)
• Yong‑Seok Choi(RAMP Convergence Research Center, Korea Institute of Science and Technology (KIST), 92 Chudong‑Ro, Bongdong‑Eup, Wanju‑Gun, Jeonbuk 55324, Republic of Korea)
• Yong Chae Jung(RAMP Convergence Research Center, Korea Institute of Science and Technology (KIST), 92 Chudong‑Ro, Bongdong‑Eup, Wanju‑Gun, Jeonbuk 55324, Republic of Korea) Corresponding author
• Yebom Kim(RAMP Convergence Research Center, Korea Institute of Science and Technology (KIST), 92 Chudong‑Ro, Bongdong‑Eup, Wanju‑Gun, Jeonbuk 55324, Republic of Korea, Department of Chemical Engineering, Jeonbuk National University, 567 Baekje‑Daero, Deokjin‑Gu, Jeonju‑Shi, Jeonbuk 54896, Republic of Korea)
• Sungho Lee(RAMP Convergence Research Center, Korea Institute of Science and Technology (KIST), 92 Chudong‑Ro, Bongdong‑Eup, Wanju‑Gun, Jeonbuk 55324, Republic of Korea, Department of Nano Material Engineering, KIST School, University of Science and Technology (UST), 217 Gajeong‑Ro, Yuseong‑Gu, Daejeon 34113, Republic of Korea)
• Sung‑Kon Kim(Department of Chemical & Biochemical Engineering, Dongguk University, Seoul 04620, Republic of Korea)