Laboratory Manufacture of High Moisture Southern Pine Strandboard Bonded with Three Tannin Adhesive Types‪.‬

Abstract Three types of tannin-based adhesives (wattle, quebracho, and radiata pine) were examined as binders for strandboard panels at two binder solids (10% and 13%) application levels. The strand moisture content (MC) was 6 percent or higher with an objective of having an out-of-press panel MC of 6 percent or higher. Characteristics (viscosity, stability, and gel time) of the tannin solutions and final tannin adhesives with cross-linking compounds are described. The strandboard panels were tested for internal bond, bending properties, durability after an accelerated aging test, and thickness swell after exposure to water. The preliminary panels bonded with 10 percent binder solids and 5.5 to 6.5 percent MC strands showed some promising test results, with some exceptions meeting or exceeding Canadian standards for strandboards. The final series of panels had varied physical/mechanical test results, due in part to strand MCs that were as high as 8.6 percent. Further work is suggested on fine-tuning the cross-linking compounds and the press processing parameters for tannin adhesives for strandboard manufacture.