Synergistic flame retardant modification of bio‐based nylon 56 by graphitic carbon nitride and melamine cyanurate

Abstract To address the flammability drawbacks of nylon 56 and expand the application range of bio‐based nylon 56, melamine cyanurate (MCA) was employed through self‐assembly in a solvent with graphitic carbon nitride surface treatment. Modified MCA (CNMCA)composition and morphology were investigated. CNMCA created with surface treatment and polyamide 56 (PA56) prepared with unmodified MCA had their flame retardant functions and mechanical properties investigated and compared. x‐ray diffraction (XRD) and Fourier transform infrared (FT‐IR) spectroscopy confirmed the successful microencapsulation of g‐C 3 N 4 on the MCA surface. Further characterization of the unmodified MCA and CNMCA was performed using scanning electron microscopy (SEM). The SEM images revealed a significant reduction in the degree of agglomeration in CNMCA compared to conventional MCA, resulting in a more uniform dispersion in the PA56 matrix. Additionally, PA56/CNMCA achieved a UL94 V‐0 rating and a limiting oxygen index (LOI) value of 30.1%. Notably, compared to pure PA56, PA56/CNMCA30 exhibited the most promising synergistic effect, leading to a separate reduction of 45.45% in the total heat release rate (THR) and 13.62% in the total smoke release (TSR). Consequently, with the same flame retardant addition (10 wt%), the CNMCA flame retardant showed superior dispersion in the bio‐based nylon 56 matrix compared to traditional MCA. Due to the physical isolation of g‐C 3 N 4 , the synergistic effect of MCA and graphitic carbon nitride imparted better mechanical properties and flame resistance to nylon 56. Highlights MCA/g‐C 3 N 4 hybrids were prepared and applied in bio‐based nylon 56 for the first time. The MCA/g‐C 3 N 4 hybrid has better dispersion than MCA. PA56/MCA/g‐C 3 N 4 flame retardant composites have better flame retardant and smoke suppression properties than PA56/MCA.