Layered double hydroxide reinforced thermal expansion fire extinguishing agent for potential solid fire prevention

In this work, phosphorus-decorated Zn-Al-CO3 layered double hydroxide (PLDH) was prepared via a co-precipitation strategy and thus introduced into intumescent flame retardant dispersion to fabricate PLDH-reinforced thermal expansion fire extinguishing agent (FEA@PLDH). It was found that the phosphorus-containing unit was successfully anchored onto the PLDH. The prepared FEA@PLDH solution with a viscosity of 146 mPa·s exhibited good interfacial compatibility with the ethylene-vinyl acetate (EVA) surface. Taking advantage of the synergistic catalytic carbonization and expanded insulating barrier effects of FEA@PLDH, the corresponding coated EVA (EVA-FEA@PLDH1) with 1 wt% of PLDH could form a continuous and compact carbonaceous block layer under fire or high-temperature conditions. Meanwhile, the LOI for EVA-FEA@PLDH1 was increased from 22.0% to 32.0% and reached the UL-94 rating of V0. Moreover, EVA-FEA@PLDH1 showed delayed TTI (77 s) and TPHRR (146 s), with 6% and 44% reductions in THR and TSP, respectively, and 43% increment in residual char, as compared to the EVA-FEA. In addition, fire resistance experiment revealed that EVA-FEA@PLDH1 could withstand the ∼1300 °C flame for 467 s longer than that of the EVA-FEA (171 s). This research provides an intriguing fire extinguishing agent for the potential fire prevention of flammable polymer materials.