Silane coupling agent and carboxymethyl chitosan co‐modified boron nitride for preparing silicone acrylic emulsion‐based flame‐retarding coatings

Abstract Herein, the synergistic effect of the silane coupling agent (KH550) and carboxymethyl chitosan (CMCS) co‐modified boron nitride (BN) on the fireproof property of silicone acrylic emulsion‐based composite is investigated to explore halogen‐free coatings for flame‐retarding plywood. Firstly, KH550 and CMCS co‐modified BN improves its compatibility with the silicone acrylic emulsion. The results show that an appropriate loading of BN (2 wt%) enhances flame retardancy. The peak‐heat release rate decreases from 86.01 to 54.95 kW m −2 , with the reduced fire growth index decreasing from 0.31 to 0.16 kW m −2 s −1 , and the average effective heat of combustion drops from 0.99 to 0.85 kW g −1 . Meanwhile, the x‐ray diffraction results demonstrate that the co‐modified BN reacts with the phosphoric acid generated by APP decomposition and transforms into BPO 4, enhances the thermal insulation of the coating. The pyrolysis kinetics confirms that the co‐modified BN increases E α at 300–380°C by 23.4% and E α at 380–430°C by 21.5%. The water contact angle clarifies that the co‐modified BN significantly imparts higher water resistance to the coating. Generally, the high thermal conductivity of co‐modified BN effectively achieves heat dissipation and facilitates the uniform charring of the composite coating, leading to the as‐formed resilient residues for blocking flame development.