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

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 BPO4, enhances the thermal insulation of the coating. The pyrolysis kinetics confirms that the co-modified BN increases E-a at 300-380? by 23.4% and E-a at 380-430? 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.

Automated summary

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 was investigated. The results showed that an appropriate loading of BN enhanced flame retardancy and improved the water resistance of the coating. The co-modified BN reacted with phosphoric acid and increased the thermal insulation of the coating.