Open Access

ARTICLE

Study on the Soy Protein-Based Adhesive Cross-Linked by Glyoxal

Zhigang Wu^1,2,#, Jiankun Liang^3,#, Hong Lei^1,*, Bengang Zhang¹, Xuedong Xi¹, Lifen Li²

1 Yunnan Provincial Key Laboratory of Wood Adhesives and Glued Products, Southwest Forestry University, Kunming, 650224, China
2 College of Forestry, Guizhou University, Guiyang, 550025, China
3 Kaili University, Qiandongnan, 556011, China

* Corresponding Author: Hong Lei. Email:
# The two authors contributed equally to this work

(This article belongs to the Special Issue: Renewable and Biosourced Adhesives)

Journal of Renewable Materials 2021, 9(2), 205-218. https://doi.org/10.32604/jrm.2021.013655

Received 15 August 2020; Accepted 27 October 2020; Issue published 15 December 2020

Abstract

Based on the ESI-MS and ¹³C-NMR analysis of the forms of glyoxal in acidic and alkaline solutions, the soy-based adhesive cross-linked by glyoxal was prepared in this work. The results showed that glyoxal existed in water in different forms at different pH levels. Under alkaline conditions, glyoxal transformed to glycolate through the intramolecular disproportionation reaction. Under acidic conditions, although some of glyoxal transformed to glycolate as what happened under alkaline conditions, most of glyoxal molecules existed in the form of five- or six-membered cyclic ether structure. No ethylene tetraol or free aldehyde group was actually detected under these conditions. Although glyoxal reacted with soy protein under both acidic and alkaline conditions, alkaline conditions were more favorable for the improvement of mechanical performance and water resistance of soy-based adhesives than acid conditions.

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