Melamine-urea-formaldehyde resin adhesives for cross laminated timber production under radio frequency heating

As the science and technology of fabricating cross laminated timber (CLT) as a way of mass timber use advances in these days, the selection of adhesives for the CLT production is an important issue. This work focuses on the use of melamine-urea-formaldehyde (MUF) resin adhesives for CLT production as a way of replacing with current polyurethane adhesives. Different sets of 3-ply CLT panels were prepared by bonding Larch lumbers with MUF resins synthesized in the laboratory, using a radio frequency (RF) heating system. CLT panels were successfully fabricated with MUF resins under the RF system. Determination of the adhesion strength of the CLT bonded with MUF resins showed that the delamination percentage of the CLT was about 7%, which met the requirement of water proof resistance after an accelerated aging test. These results suggested that the combination of MUF resin adhesives with RF heating was a good alternative of producing CLT in a short production time. And MUF resin adhesives could replace cold-setting polyurethane adhesives for CLT production under RF heating system.