TY  - EJOU
AU  - Younesi-Kordkheili, Hamed 
AU  - Pizzi, Antonio 

TI  - Synthesis of Lignin-Based Polyacid in an Acidic Ionic Liquid: A Green Method to Improve the Performance of Lignin as Catalyst in Urea-Formaldehyde Resin
T2  - Journal of Renewable Materials

PY  - 2022
VL  - 10
IS  - 2
SN  - 2164-6341

AB  - The aim of this research was to investigate the effect of ionic liquid treated lignin-based polyacid as a catalyst for urea-formaldehyde (UF) resins. Esterification of lignin was carried out, without any catalyst, with anhydride maleic and 1-butyl-3-methylimidazolium hydrogen sulfate [Bmim][HSO<sub>4</sub>] as acidic ionic liquid to form maleated lignin-based polyacids (MA-IL). The performance of MA-IL as UF resin catalyst was respectively compared to hyroxymethylated lignin-based polyacid (MA-HL) and to NH<sub>4</sub>Cl. The FTIR analysis indicated that the proportion of -COOH and C-O bonds increased due to the esterification of lignin with ionic liquid rather than its hyroxymethylation. Physicochemical tests indicated that the gelation time of the UF resin was shorter by adding MA-IL when compared to NH<sub>4</sub>Cl and MA-HL, respectively. DSC analysis showed that the addition of MA-IL significantly decreased the temperature peak (Tp) of the UF resin; as the Tp of the UF resin with 2 wt% MA-IL was lower than with MA-HL and NH<sub>4</sub>Cl, respectively. The panel test results of plywood bonded with a UF resin with a MA-IL level increasing from 1% to 3%, effectively improved the mechanical strength, water resistance and formaldehyde emission even higher than with MA-HL and NH<sub>4</sub>Cl, respectively.
KW  - Lignin-based polyacid; maleic anhydride; ionic liquid; esterification; plywood

DO  - 10.32604/jrm.2022.017851