Utilization of White Fir Bark in Particleboard

The suitability of white fir bark for making particleboard was evaluated. The white fir bark in this investigation contained around 10.5 percent of formaldehyde reacting polyphenolics. When 2 percent of paraformaldehyde was added to the bark furnish and processed into a board, the formalde hyde released during the hot press cycle reacted with the polyphenolics to form a board with waterproof properties indicated by thickness swelling of around 12 percent after the 2-hour boil test. While the bark board had good internal bond, water absorption, and thickness swelling values, it had a low MOR of less than 1000 psi and high linear expansion of over 1 Percent. When the bark furnish was used as core stock in a three-layer wood-bark particleboard, the strength properties were greatly improved, to MOR of over 1800 psi and resulted in a very low linear expansion value of around 0.26 percent producing a board with good overall properties. Homogeneous boards containing around 25 per cent bark also produced boards with satisfactory properties.

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