Abstract
Phenolic aerogel is one of the most widely used lightweight thermal protective materials at present. With changes in the application environments, higher requirements are put forward for the heat resistance and mechanical properties of phenolic aerogel. In this paper, boric acid was used to modify phenolic resin, and then boron-modified phenolic aerogel was prepared. The chemical structure of modified phenolic resin was studied by infrared spectroscopy (FTIR). The microstructure, thermal stability, heat resistance in air, and compression resistance of phenolic aerogel were studied by volume shrinkage, scanning electron microscope, thermogravimetric analysis, high-temperature combustion test, and mechanical test. The results showed that the modification introduced boron oxygen bonds on the phenolic main chain. The compatibility difference between boron and phenolic resin with different content has a significant impact on the performance of phenolic aerogel. When boron content is 5-10% of phenolic resin, the network structure and thermal stability of phenolic aerogel can be significantly improved, and the maximum compressive strength of phenolic aerogel can also be improved. Boron-modified phenolic aerogel is expected to play an important role in the field of thermal insulation.