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

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Abstract
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 1H and 13C 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.) 13C and 15N 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.