Thermal Insulation Characteristics of Polybenzoxazine Aerogels

Abstract Polybenzoxazine (PBO) aerogels with low densities and low thermal conductivities are prepared from Bisphenol A (BPA) benzoxazine monomers by ring‐opened polymerisation using HCl as a catalyser at 10 °C. The obtained PBO aerogels have cross‐linked and 3D network structures with the densities ranging from 0.084 to 0.526 g cm −3 . The thermal conductivities under different pressures (3–10 5 Pa, air) and different atmospheres (N 2 , Ar, and CO 2 , 10 5 Pa) are investigated. The thermal conductivities are in the range of 0.0335–0.0652 W m K −1 under ambient pressure and 0.0098–0.0571 W m K −1 at 3 Pa. The thermal transfer mechanism under different gas pressures is analyzed with increasing pressure. Under different atmospheres, the thermal conductivities decrease as the molecular weight of the gas increases. Compared with the traditional organic foam insulating materials of phenolic foam, polyurethane and polystyrene, which have similar apparent densities, PBO aerogels exhibit lower thermal conductivity of 0.0335 W m K −1 than that of traditional organic foam at room temperature.