The thermal degradation of a series of cured melamine‐formaldehyde resins and of two relevant model compounds has been investigated using thermogravimetry accompanied by the analysis of volatile products. Low temperature degradation reactions which occur up to ∼350°C involve the loss of water and formaldehyde, the latter arising from reversible demethylolation reactions. It is proposed that ether linkages, which model compound studies indicate would yield formaldehyde in the low temperature region, are not present to any significant degree in cured resins. Deep‐seated rupture of the polycondensate system takes place at temperatures above ∼375°C when a number of independent reactions involving both side‐chain and ring degradation give rise to products among which ammonia, hydrogen cyanide, carbon monoxide and melamine have been examined.

The possible course of methylolation and subsequent crosslinking steps in melamine-formaldehyde resins has been investigated by using two model compound systems, viz., 2-amino-4,6-diphenoxy-s-triazine and 2-amino-4,6-diphenyl-s-triazine. The reactions of these models with formaldehyde and the secondary thermally induced condensation reactions have been examined, in particular, by the use of thin-layer chromatography and by nuclear magnetic resonance and infra-red spectroscopy. Methylolated products crosslink by forming ether and methylene bridges at --120", the former being readily converted to the latter when the temperature is varied to -135". Ether bridge degradation releases formaldehyde which further reacts in part at available N-H sites. The conversion of ether bridges to methylene bridges is enhanced by the attachment of phenyl groups to the triazine ring.