Preparation of Carbon Foam Insulation Material from Polyurethane Foam Impregnated with Phenolic Resin Solution

Using polyurethane foam as template and thermosetting borated phenolic resin as carbon source, reticulated glass carbon (RVC) foams were prepared by liquid phase impregnation and drying, oxidation stabilization and high temperature pyrolysis processes. The phase composition, pyrolysis and shrinkage process, high temperature heat insulation (1 200 ℃) and compression properties of the material were tested and analyzed. The effects of concentrations of carbon sources on the density, shrinkage and microstructure of RVC foams were studied. The results of the physical and chemical property tests and SEM showed that the diameter distribution of RVC foams were uniform (200-500 μm), and the densities were low (0.041-0.065 g/cm3). The average pore size of the material could be increased by the concentration of impregnation solution. The effective carbon residual rate of RVC foam increased from 32.6% to 49.5%, and the linear shrinkage rate decreased from 20% to 5%. The thermogravimetric process showed that the oxidation stabilization treatment could transform the thermoplastic phenolic resin into thermosetting resin which could stably adhere to the polyurethane preform skeleton during the pyrolysis and carbonization stage, avoiding the stress and macroscopic defects in the final carbon foam structure. The thermal conductivities of RVC materials in the experimental density range were negatively correlated with the density, which could be as low as 0.339 W•(m•K)-1 at 1 200 ℃, showing good thermal insulation performance. At the same time, the stress-strain curves of the material showed good static compression toughness, which could be used in the field of thermal protection. © 2022, Materials Review Magazine. All right reserved.