Performance effectiveness of addition to UF of melamine salts vs. melamine alone in MUF adhesives for plywood

摘要

ENSTIB, University of Nancy 1, Epinal, France Materials and methods To a commercial UF resin of U:F molar ratio of U:F of 1:1.5 were added or 10% melamine powder alone on weight of urea in the UF resin, or 10% melamine as pure melamine monoacetate and in both cases NH_4Cl hardener as a 25% solution as indicated in the Table. These resin glue-mixes were tested dynamically by thermomechanical analysis (TMA) on a Mettler apparatus. Triplicate samples of beech wood alone of dimension 21 x 6 x 0.6 mm, and of two beech wood plys bonded with each system in a layer of 0.2 mm when cured, for a total samples dimensions of 21 x 6 x 1.4 mm were tested in non-isothermal mode between 40 ℃ and 220 ℃ at a heating rate of 10 ℃/minute with a Mettler 40 TMA apparatus in three points bending on a span of 18 mm exercising a force cycle of 0.1/0.5 N on the specimens with each force cycle of 12 seconds (6s/6s).