The thermo‐oxidative degradation of phenol–formaldehyde polycondensates: Thermogravimetric and elemental composition studies of char formation

摘要

AbstractAn investigation of the char formation process during the thermal‐oxidative degradation of phenol‐formaldehyde polycondensates by thermogravimetric analysis and elemental analyses of the degraded residues has been found to support the char‐forming proposals previously reported. The resins investigated, once fully cured at elevated temperatures, were all found to degrade identically under the conditions studied despite differences in the phenol‐formaldehyde ratios of the liquid resins. Test data indicated that the elevated temperature degradation is fundamentally associated with the chemical stability of the dihydroxydiphenylmethane unit. Small differences in the mode of degradation were observed up to 300°C. and could be attributed to the post‐curing processes and volatilization of solvent and other low molecular weight species. The present study presents a useful alternate approach to the study of high temperature degradation, based on residue analyses, which when coupled with data obtained by other methods allows a more complete evaluation of resin degradation in the temperature range