Synthesis, Structure, and Characterization of Glyoxal-Urea-Formaldehyde Cocondensed Resins

To decrease the formaldehyde emission of urea-formaldehyde (UF) bonded products at source, monomethylol urea (MMU) was chosen to react with glyoxal (G), a nonvolatile and nontoxic aldehyde, to prepare a novel glyoxal-urea-formaldehyde (GUF) cocondensed resin. The GUF resins were synthesized with different MMU/G molar ratios, and the basic properties were tested. The GUF resins were characterized by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, carbon-13 nuclear magnetic resonance spectroscopy and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). The results show that the synthesized GUF resins remain stable for at least 10 days at ambient temperature. Conjugated structures, and large amounts of -OH, -NH-, C-N, and C=O groups with different levels of substitution exist in the GUF resin. There are two repeating motives in the MALDI-TOF-MS spectrum of the GUF resin, one of 175 +/- 1 Da and a second one of 161 +/- 1 Da. Moreover, the peaks due to the dehydration condensation reaction of MMU also appear in the spectra. (C) 2014 Wiley Periodicals, Inc.