Effect of spent sulfite liquor on urea–formaldehyde resin performance

ABSTRACT Combination of urea–formaldehyde (UF) resins with technical lignins has been often reported in the literature. However, the actual implications of this approach have not been effectively addressed yet. In this work, unmodified thick spent sulfite liquor (TSSL) and hydroxymethylated TSSL (TSSLH) were incorporated in a standard UF resin in different amounts (10 and 20%) and at different stages. When 10% of TSSLH was incorporated after the synthesis, the produced particleboards performed equivalently to when 90% of UF resin was used. In all other cases tested, combining UF resin with TSSL/TSSLH actually led to lower internal bond strengths. The results evidence that addition of TSSL or TSSLH does not have a beneficial effect on UF bonding performance. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47389.