Characterisation of some melamine‐formaldehyde condensates and some cured resins by ¹H, ¹³C and ¹⁵N n.m.r. spectroscopy

Some oligomeric species (condensates) in a melamine‐formaldehyde adduct mixture have been isolated by preparative high performance liquid chromatography (h.p.l.c.) and partly identified by high field 1 H and 13 C nuclear magnetic resonance (n.m.r.) spectroscopy. The oligomers are shown most likely to be largely dimers, trimers and tetramers and to contain both methylene and methylene ether linkages. Some cured melamine‐formaldehyde resins are shown by solid‐state cross‐polarisation magic angle sample spinning (c.p./m.a.s.) 13 C and 15 N n.m.r. to contain linear and branched methylene and methylene ether linkages but few free methylol groups. The relative proportions of the various linkages in both the oligomers and the cured resins appear to be controlled mainly by the melamine: formaldehyde ratio.