Siti Hanim Hj. Sahari & Nigel P. T. Lim Effect of Molar Ratio Variation in Melamine Urea Formaldehyde Resin on Formaldehyde Emission and Bonding Strength of Plywood
Low Formaldehyde Emission melamine urea formaldehyde (MUF) resin adhesive can be formulated by secondary additions of urea and melamine. This can be achieved by lowering the molar ratio of formaldehyde to urea and melamine during the synthesis of the resin.
In this study, the molar ratio of formaldehyde to urea/melamine in the resin was lowered from 2.25 to 1.5 and 1.125 respectively. Six different compositions of MUF resins were formulated using varying quantities of urea and melamine whilst that of formaldehyde content remained the same. These resins were subsequently applied on to veneers of Red Meranti (Shorea spp.) to produce 30cm X 30cm 3-ply test panels of plywood. Delamination test and emission of formaldehyde were conducted on the plywood samples for their compliance to Japanese Agricultural Standard JAS of Common Plywood (1973).
It was generally observed that resins with a high melamine content possessed low formaldehyde emission and exhibited better bonding strength. These observations were further confirmed by conducting the analyses of resin structures using 13C-NMR spectroscopy.