Enhancing Flame-Retardant Properties of Polyurethane Aerogels Doped with Silica-Based Particles.

In this work, polyurethane (PUR) aerogels doped with different SiO particles, derived from a renewable source, were successfully synthesized, and the effects of SiO content on the properties of PUR aerogels were investigated. Specifically, three types of SiO-based particles obtained from rice husk through different procedures were evaluated to enhance the thermal stability of the composites with special attention given to flame-retardant properties. With the optimal SiO particles, obtained through acid digestion, the influence of their content between 0.5 and 3 wt.% on the physicochemical characteristics of the synthesized aerogels was thoroughly examined. The results showed that increasing the doping agent content improved the lightness, thermal stability, and flame-retardant properties of the resulting PUR aerogels, with the best performance observed at a 2 wt.% doping level. The doped aerogel samples with non-modified SiO particles significantly enhanced the fire safety performance of the material, exhibiting up to an eightfold increase in flame retardancy. However, modification of the SiO particles with phytic acid did not slow down the combustion velocity when filling the aerogels. This research highlights the promising potential of doped PUR/SiO aerogels in advancing materials science and engineering applications for withstanding high temperatures and improving fire safety.