TPP-SiO₂ Aerogel synergistic modification of polyurea composites towards mechanical shock wave mitigation and flame retardancy

In industrial explosion accidents, mechanical shock waves and flame thermal radiation are the main destructive factors, posing serious threat to life and property. Current designs mainly focus on one of these factors, so it is necessary to develop protective materials against both destructive factors. TPP (Triphenyl phosphate) - SiO₂ Aerogel synergistically modified polyurea composites were developed in this work, which process excellent mechanical shock wave mitigation performance and enhanced flame retardancy. The mechanical shock wave mitigation experiments were conducted on Multi-purpose Shock Cannon (MSC), Human Tissue Equivalent Target (HTET) and full-scale human head model, which comprehensively evaluated the protective performance of polyurea composites for the human body. The flame retardancy was assessed through thermal conductivity, LOI, thermal gravimetric and small flame experiments. The combustion residue was analyzed using SEM, EDS, Raman spectroscopy, and XPS technologies, revealing flame retardant mechanism of TPP-SiO₂ Aerogel synergistically modified polyurea composites. The results showed thatTPP-SiO₂ Aerogel synergistically modified polyurea composites achieved the highest mitigation ratios of overpressure peak and acceleration peak at 13.20 % and 60.87 %, respectively, superior to those of fiber-enhanced polymer composites (Fiber-PE, Fiber-PA6, Fiber-ASA), single filler polyurea, wood and PLA plastic. The flame retardancy was effectively improved, with the highest LOI reaching 24.9 %, far higher than that of pure polyurea (19.6 %). It particularly enhanced the carbonization performance of polyurea composites during combustion, eliminating burning material dropping phenomenon. The thermal insulation performance was also elevated, with the lowest thermal conductivity reduced by 58.6 % compared to pure polyurea.