Lightweight Nitrogen-Doped Phenolic Aerogels with Flame-Retardant and Thermal-Insulation Properties
Junxiang Cao, Peng Wang, Hongxiang Cai, Bo Niu, Yayun Zhang, Donghui Long
Abstract
The inherent flammability of phenolic aerogels has imposed significant limitations on its utilization. In order to unlock the potential of phenolic aerogels as insulation and flame-retardant materials, we fabricate a series of melamine-phenolic aerogels (MPAs) based on a copolymerization reaction of melamine and phenolics in a sol–gel process. By varying the quantity of melamine, the microstructures and the corresponding thermal properties of MPAs are investigated. The results indicate that MPAs possess ultralow thermal conductivity of 0.036–0.038 W/(m·K) and a density of 0.34–0.40 g/cm 3 . In addition, melamine greatly increases the flame retardancy of phenolic aerogels. A modified phenolic aerogel containing 40 wt % melamine has a limiting oxygen index (LOI) value of 32.7%. The measured maximum heat release rate values of MPAs decrease with the increase of melamine portions in samples, ranging from 138 to 74 kW/m 2 in the cone calorimeter testing experiment. Furthermore, TG-MS-FTIR technology is used to analyze the gas emission during thermal decomposition, and the structure evolution of the solid phase is studied for a better understanding of the flame-retardant mechanism. This research is intended to present phenolic-based aerogel materials with outstanding overall performance and explore their potential for large-scale production in the future.