EFFECTS OF DIFFERENT FLAVONOID EXTRACTS IN OPTIMIZING TANNIN-GLUED BARK INSULATION BOARDS

Efforts in decreasing energy consumption in buildings have created a market environment that favors insulation materials made from renewable resources. Tree bark is a naturally highly optimized material that can serve insulation needs. Thus, bark insulation panels have been produced from larch bark and bonded with a formaldehyde-free tannin-hexamine resin. Quebracho and mimosa tannins, containing different levels of hexamine, were mixed with bark particles at different ratios, and cured in a hot press for various press times. Mechanical and water-related board property evaluation showed mimosa tannins to be advantageous in terms of panel performance. This was supported by Fourier transform infrared (FTIR) spectroscopic analysis of tannin polymers, which provided insight into the chemical activation by a hardener and possible rationale for the better performance of mimosa resin. Evaluating thermal conductivity of the panel showed that its dependence on temperature was comparable with commonly available insulation materials.