The Effect of Nanoclay on Melamine-Urea-Formaldehyde Wood Adhesives

In this work it has been shown that the addition of small percentages of Na+-montmorillonite (Na-MMT) and organic modified-montmorillonite (O-MMT) nanoclay to thermosetting melamine-urea-formaldehyde (MUF) resins appeared to improve, considerably, their performance as adhesives for wood particleboard. X-ray diffraction (XRD) studies indicated that Na-MMT when mixed in small proportions, loses the periodic atomic structure during the curing of MUF resins. This can be interpreted as becoming exfoliated under such conditions. Thermomechanical analysis (TMA) on laboratory MUF-bonded particleboard indicated that small percentages of Na-MMT and O-MMT improved the internal bond strength imparted by the MUF adhesive to the panel, when tested dry and also, more importantly, when tested after 2 h of boiling. The increase in water resistance of the MUF-bonded panel was particularly noticeable. Furthermore, the addition of Na-MMT was shown to increase considerably the resistance of the MUF resin to abrasion. This is important from a wood surface finish point of view. (C) Koninklijke Brill NV, Leiden, 2012