Thermal degradation of phenolic resin/silica hybrid ceramers

The kinetic parameters and the structural change of thermal degradation of phenolic resin/silica hybrid ceramers with different mixing ratios were investigated. The activation energies of thermal degradation were calculated by the methods of Kissinger, Friedman and Ozawa from a conventional dynamic thermogravimetric measurement in nitrogen atmosphere at several different heating rates. Both pure phenolic resin and hybrid ceramers show two stages of degradation; however, the activation energies of thermal degradation of the ceramers in the first stage are all lower than that of phenolic resin. FT-IR spectra show that the formation of silica network structure was restricted by intermolecular hydrogen bonding at lower temperature. However, the restriction disappears when the phenolic resin starts to degrade at high temperature. TGA/MS investigations show that the presence of sor-gel silica causes some changes in the degradation mechanism of the hybrid ceramers. (C) 2000 Elsevier Science Ltd. All rights reserved.