A water-soluble polycarboxylic acid (PCA) resin was assessed for ability to
limit moisture swelling of densified wood. Aspen flakes were treated in 0
(control), 1, 5, 10, and 20% PCA resin solutions and drained for 1, 10, and
20-min time periods. Following treatments, flakes were compressed to rough
ly 50% strain at 170 degreesC. The: PCA content of flakes significantly inc
reased with increasing concentration and drain time. Water absorption and t
hickness swell of flakes decreased with increasing PCA content. Both water
absorption and thickness swell of untreated flakes were over 100%; but for
PCA-treated flakes, water absorption and thickness swell as low as 45% and
16%, respectively, were achieved. Irreversible thickness swell decreased wi
th increasing PCA content, while reversible thickness swell remained relati
vely constant. The swelling coefficient decreased with increasing PCA conte
nt, a behavior that often is associated with bulking agents for treated, un
compressed wood. However, dynamic mechanical analysis further suggested tha
t PCA resin acts as a cross-linking agent to stabilize the position of the
collapsed cell walls.