Flame protection capability of waterborne epoxy coatings enhanced by inorganic-organic phenyl zirconium phosphate anchored boron nitride

Zirconium phenyl phosphate (ZrPP) has good compatibility in polymers due to its simultaneous inorganic-organic structure. Here, ZrPP was anchored on high barrier boron nitride (BN) by an in situ synthesis scheme using polyaniline (PANI) as an intermediate, which is expected to yield a high performance multifunctional composite flame retardant. Among them, the formation of a rational composite structure of ZrPP and BN is conducive to the maximum enhancement of its barrier effect. Moreover, the presence of Zr and phosphoric acid molecules can effectively promote the cyclization of cleaved molecules and carbon formation in the burning stage, which reinforced the quality and strength of residual carbon. The results showed that the back side temperature of BP@ZrPP/EP waterborne coating was stabilized at the lowest value (167.2 °C), accounting for the most excellent thermal insulation effect of its residual carbon. The BP@ZrPP/EP composite coating showed the maximum expansion height (23.8 mm), expansion rate (18.03) and residual carbon (31.8 %), which depends on the synergistic barrier function of ZrPP and BN. Further, BP@ZrPP based EP exhibited the smallest smoke density rating (38.2 %), the largest limiting oxygen index (31.4 %), and achieved a V0 rating for the UL-94 test. Compared with EP, the peak heat release rate (PHRR), total heat release rate (THR), peak smoke production rate (PSPR), total smoke production (TSP), and peak CO production rate (PCOPR) of BP@ZrPP-filled EP were reduced by 32.9 %, 30.7 %, 33.3 %, 31.3 %, and 35.4 %, respectively, proving its excellent flame retardant and smoke inhibition ability.