Thermal Stability of Substituted Phenol-formaldehyde Resins

A variety of crosslinked phenol-, or derivatized phenol-formaldehyde polymers have been synthesized. the phenol derivatives included o- and p-cresol, p-nonylphenol, m-pentadecylphenol, and raw and distilled cashew nutshell liquid. the derivatives were copolymerized with phenol and formaldehyde using sulfuric acid as catalyst to yield novolak-type prepolymers, which are then cured with hexamethylenetetramine. Thermogravimetric analysis was used to evaluate the thermal stability of the cured resins. the trend in thermal stability of the resins may be explained on the basis of alkyl groups being less thermally stable than aromatic rings. the amount of hexamethylenetetramine used to cure the prepolymers also influences the thermal stability of the resin