Flame-retardant, lightweight, and multiple safeguarding fire alarm sponge for firefighter safety detection

A fire alarm sponge with multiple protection functions is prepared by high-temperature foaming method. We comprehensively evaluate its impact protection, thermal protection , flame retardant and fire alarm performance. The sponge not only exhibits excellent mechanical and thermal protection, but also has excellent flame resistance, which makes it alarm in fire for more than 3600 s. • The FGSE sponge showed multiple protections such as flame, thermal and impact. • Mechanical analysis confirmed the mechanical stability of the FGSE. • The flame retardant properties were thoroughly tested and systematically analyzed. • The FGSE has excellent fire resistance and the ability for ultra-long alarm durations. • The fire alarm system enabled secure monitoring without distance restrictions. Fire alarm materials played a critical role in the safety of fireman and have gained increasing attention recently. However, the lifetime of traditional reported fire warning materials was short under durable flame attack. Considering explosions and building collapse occurred frequently in fire accidents, developing fire warning sensors with the coupling protection against heat, fire, kinetic impact for advanced flame guarding equipment remained a huge challenge. Here, a multifunctional flame-retardant GO-shear stiffening elastomer (SSE)-EVA sponge (FGSE) featured multiple safeguarding and notable flame tolerance properties was developed by incorporating GO into flame-retardant SSE-EVA composite (FSE). The FSE was prepared by mixing expanded graphite, ammonium polyphosphate with SSE and EVA followed by foaming treatment. Firstly, pure SSE-EVA sponge prepared by foaming SSE and EVA mixture presented low density of 0.41 g/cm 3 and 97.8 % shape restoration after 90 %-compressive strain. Importantly, inheriting from the mechanical energy dissipation of SSE, SSE-EVA effectively dissipated impact force from 2625 N to 319 N. Moreover, the limiting oxygen index of FSE with good flame-retardance attained 30 %. Additionally, the incorporation of GO endowed FGSE with temperature sensing characteristics which the resistance rapidly transitioned from insulation to 572 Ω under flaming crashes, and the alarm duration extended to extreme 3600 s. Eventually, an impact-protected flame alarm sensor with multi-channel long-distance system was designed for safety detection in fire rescues.