Analyses of cocondensation of melamine and urea through formaldehyde with carbon 13 nuclear magnetic resonance spectroscopy

Abstract

The ¹³C-NMR (carbon 13 nuclear magnetic resonance) spectra of urea-formaldehyde (UF) resins, melamine-formaldehyde (MF) resins, and melamine-urea-formaldehyde (MUF) cocondensed resins synthesized under various conditions were taken with a frequency of 75 MHz. The main purpose was to investigate whether or not the occurrences of cocondensation between melamine and urea through the formation of methylene or dimethylene ether linkages could be identified. The signals due to carbons of methylene linkages of UF resins were distinguishable from those of MF resins. The signals due to carbons of cocondensed methylene linkages (-NH-CH₂-NH-), in which both nitrogen atoms are secondary, were suggested to be identifiable separately from those due to UF and MF resins. The corresponding carbons of dimethylene ether linkages of UF and MF resins could be identified clearly by the difference of their chemical shifts of 0.9 ppm. The carbon signals due to cocondensed dimethylene ether linkages were found to appear at the chemical shifts between those due to UF and MF resins.

Citation

Bunchiro, Tomita; Hse, Chung-Yun. 1995. Analyses of cocondensation of melamine and urea through formaldehyde with carbon 13 nuclear magnetic resonance spectroscopy. Mokuzai Gakkaishi 41(3):349-354