Investigation Of The Reaction Between Melamine And Unsaturated Aldehydes

The reactions between melamine and acrolein, crotonaldehyde or cinnamaldehyde were studied by 1-D and 2-D 1 H and 13 C n.m.r. spectroscopy. Regardless of the type of the unsaturated aldehyde used, all spectra of the resins have common characteristic regions, indicating that in the first step of the reaction similar reactive oligomers are formed. The oligomers further react via different mechanisms to form crosslinked products. Of the aldehydes, acrolein is the most reactive, while cinnamaldehyde is the least reactive. The rate of the reactions depends on reaction conditions, on molar ratios and on the type and quantity of the catalysts. Crosslinking of the resins with acids or amines gives insoluble products with a low content of monomers and oligomers.