Thermal stability of novolac cured with polyborosilazane

To improve the thermal stability of phenolic resins, silicon- and boron-containing phenolic resin (SBPR) was synthesized from novolac-type phenolic resin using polyborosilazane (PBSZ) as curing agent, which can react with novolac resin at room temperature. The curing mechanism was studied by Fourier Transform infrared spectroscopy. The thermal and morphological properties of SBPR were studied by thermogravimetric analysis (TG) and scanning electron microscopy (SEM) respectively. TG results showed that the thermal properties of SBPR were much better than the corresponding novolac resin cured with hexamethylenetetramine, both for the initial decomposition temperatures (Td) and residual weight at 900 degrees C. The SEM and EDX results showed that the SBPR hybrids after oxidation were covered with SiO2 glass coatings, which improved the thermo-oxidative resistance of SBPR. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013