Modern methods for the analysis of urea formaldehyde resins

Modern instrumental techniques were used for analysing water-based urea-formaldehyde resins. An exhaustive study was made of the silylation of such a resin with BSTFA (N,O-bistrimethylsilyltrifluoroacetamide). From the gas chromatograms the amounts of urea, monomethylol urea and dimethylol urea can be determined quantitatively, thus giving information on the low molecular weight part of the resin. The ratio of low to high molecular weight components as well as the amounts of several low molecular weight compounds can be estimated from a GPC analysis on Sephadex LH 20 in water. A detailed picture of the resin is obtained when freeze-dried samples are subjected to 220 MHz 1H-NMR analysis in DMSO-d6. An overall insight into the composition of these resins can be gained when the results of the mentioned techniques are combined with those of classical chemical analyses.