Characterization and its curing behaviors of rigid phenolic foams based on cardanol

Cardanol/phenol-based foaming resol resins were prepared successfully by reacting formaldehyde with cardanol/phenol. Phenolic foams were fabricated with the above foaming resol resin and certain foaming agents. Two kinds of resol resins were characterized with Fourier transform infrared spectroscopy, rheological analysis and Scanning electron microscope. Meanwhile, the nonisothermal curing reactions of these resol resins were studied in detail using a dynamic Differential scanning calorimetry technique at a series of heating rates. The global activation energies of the reactions were determined with the Ozawa methods. The results indicated that the peak temperatures of the exothermic reactions and global activation energies of cardanol-based foaming resol resin were higher than those of phenol-based foaming resol resin, which indicated that the more complex molecular structure of cardanol-based foaming resol resin has a negative effect on the curing speed of resin.