Thermal decomposition of phenol formaldehyde resins modified with cyanuric acid

Abstract

AbstractThe thermal decomposition of cured cyanurophenol—formaldehyde oligomers (CPFR) was studied by derivatography, IR, spectra and EPR spectra. During the heating of CPFR, processes of restructuring and decomposition take place. Up to 330°C the weight losses of CPFR are smaller compared to those of phenol–formaldehyde oligomers (PFR), while above 330°C the opposite is true. Under these conditions the isocyanuric ring is destroyed. The carbonyl absorption sharply decreases at 400°C, and at 500°C there is practically no absorption. This reduction is probably a result of rearrangement of the isocyanuric rings to a secondary polymer in which nitrogen is combined in the form of cyanic links. The energy of decomposition as determined from the thermogravimetric curve is 17 to 24 kcal/mole. On the basis of the EPR sepctra and the low activation energy of destruction, we propose that radical processes play an important part during the process of curing and thermal decomposition of CPFR.