The Reinforcing Effect of O‐ C ₃ N ₄ on the Interfacial Bonding and Mechanical Properties of Ramie Fiber/Epoxy Composites

ABSTRACT Oxidized carbon nitride (O‐C ₃ N ₄ ) nanosheets, synthesized via Hummers' method oxidation of carbon nitride (C ₃ N ₄ ), offer advantages including low cost, simple production, and good dispersibility over conventional nanofillers such as carbon nanotubes etc. The O‐C ₃ N ₄ nanosheets significantly improved interfacial interactions within the ramie fiber/epoxy (O‐C ₃ N ₄ /RF/EP) composite. At an optimal O‐C ₃ N ₄ loading of 0.3 phr, the composite exhibited remarkable enhancements: interlaminar shear strength (ILSS), tensile strength, flexural strength, impact strength, and storage modulus increased by 11.3%, 15.4%, 9.0%, 7.6%, and 19.9%, respectively. Furthermore, the glass transition temperature ( T _g ) of the composite was elevated by 7.3°C compared to the baseline RF/EP (79.44°C). The effective interfacial modification achieved through O‐C ₃ N ₄ incorporation establishes these nanosheets as a promising strategy for engineering high‐performance natural fiber composites.