Thermal degradation and fire response characteristics of polymethylsilsesquioxane aerogels

Polymethylsilsesquioxane (PMSQ) aerogels, widely recognized for their exceptional thermal insulation performance, have seen increasing application in fields such as aerospace and energy-efficient buildings. However, the lack of systematic investigation into their pyrolysis and combustion characteristics has hindered comprehensive understanding of their thermal safety. This study aimed to explore the thermal decomposition behavior and flammability of PMSQ aerogels through a combination of thermal analysis and structural characterization techniques. Results showed that PMSQ aerogels were ignited under external heat fluxes of 35 kW/m², 40 kW/m², and 45 kW/m², displaying similar combustion behaviors across all intensities. The flammability was attributed primarily to the presence of methyl groups bonded to the silica framework. Pyrolysis analysis further revealed that chemical degradation of methyl groups preceded the collapse of the silica skeleton, directly impacting the structural stability. Post-combustion characterization confirmed graphitic residue and changes in chemical bonding. These findings provide new insights into the degradation mechanism and combustion risk of PMSQ aerogels, thereby addressing the insufficient understanding of their thermal safety in insulation applications caused by the lack of systematic research on their pyrolysis and combustion behaviors.