Synthesis and Characterization of Biobased Melamine Formaldehyde Resins from Bark Extractives

In this study, bark alkaline extractives from the mountain pine beetle ( Dendroctonus ponderosae Hopkins) infested lodgepole pine ( Pinus contorta Dougl.) was used to partially replace 30 wt % of melamine in formulating the biobased bark extractive–melamine formaldehyde (MF) resin. Results showed that the addition of the bark extractives and the type of solvent system used for resin formulation significantly affected the initial molecular weight, molecular structure, viscosity, curing behavior, postcuring thermal stability, and bonding performance of the resulting resins. The bark extractive–MF resins exhibited similar dry and wet bonding strengths to the laboratory made control MF resins formulated in the same type of solvent system. The liquid-state 13 C NMR study showed that bark extractives were reactants and incorporated into the resulting biobased MF resin structures. Bark extractives obtained from the mountain pine beetle infested lodgepole pine showed promise as a suitable partial replacement for melamine in MF resin formulations.