Open Access

ARTICLE

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

by Hamed Younesi-Kordkheili^1,*, Antonio Pizzi²

1 Department of Wood and Paper Sciences, Faculty of Natural Resources, Semnan University, Semnan, Iran
2 LERMAB, University of Lorraine, Epinal, France

* Corresponding Author: Hamed Younesi-Kordkheili. Email:

Journal of Renewable Materials 2022, 10(2), 237-246. https://doi.org/10.32604/jrm.2022.017851

Received 11 June 2021; Accepted 13 July 2021; Issue published 30 August 2021

Abstract

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][HSO₄] 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 NH₄Cl. 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 NH₄Cl 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 NH₄Cl, 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 NH₄Cl, respectively.

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Keywords

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