Investigation of Novel Thermosetting Copolymer-Based Monomethylolurea–Glyoxal for Wood Manufacturing

The purpose of this investigation was to design novel alternating copolymers (monomethylolurea–glyoxal, MMU–G) as adhesives for wood manufacturing. MMU–G were synthesized under acid (pH = 5) conditions. After the 120-day storage period, the MMU–G resins were used for plywood production, which exhibited a wet shear strength of about 2.15 MPa, similar to the freshly prepared MMU–G resin. The excellent water resistance and long storage stability showed that MMU–G has particular characteristics and properties all of their own, which, in certain respects, are very different from those of urea-formaldehyde (UF) adhesives. The X-ray diffraction results showed that only a few crystallinities occurred in MMU–G resins, indicating the presence of long side chains in the MMU–G polymer structures, leading to better adhesion strength than UF resins. The structure characteristics of the MMU–G resin were studied by Fourier transform infrared and electrospray ionization mass spectrometry, and a possible molecular structure has been inferred, which is consistent with spectroscopic results.