Plasma Treatment Induced Chemical Changes of Alkali Lignin to Enhance the Performances of Lignin-Phenol-Formaldehyde Resin Adhesive
  • Zhigang Wu1,#, Sicheng Chen1,#, Jiankun Liang2, Lifen Li1, Xuedong Xi3,4, Xue Deng1, Bengang Zhang3,*, Hong Lei4,*
1 College of Forestry, Guizhou University, Guiyang, 550025, China
2 Kaili University, Qiandongnan, 556011, China
3 ENSTIB-LERMAB, University of Lorraine, Epinal, 88051, France
4 Yunnan Provincial Key Laboratory of Wood Adhesives and Glued Products, Southwest Forestry University, Kunming, 650224, China
* Corresponding Authors: Bengang Zhang. Email: zbg18082968142@163.com; Hong Lei. Email: lfxgirl@163.com
# Zhigang Wu and Sicheng Chen have contributed equally to this work
(This article belongs to this Special Issue:Renewable and Biosourced Adhesives-2021)
Received 26 March 2021; Accepted 19 April 2021 ; Published online 18 May 2021
Abstract
Alkali lignin was processed by plasma and then used in modification of phenol formaldehyde resin in this study. Chemical structural changes of lignin which was processed by plasma as well as bonding strength, tensile property, curing performance and thermal property of the prepared phenol formaldehyde resin which was modified by the plasma processed lignin were analyzed. Results demonstrated that: (1) Alkali lignin was degraded after the plasma processing. The original groups were destroyed, and the aromatic rings collected abundant free radicals and oxygen-containing functional groups like hydroxyls, carbonyls, carboxyls and acyls were introduced into increase the reaction activity of lignin significantly. (2) The introduction of alkali lignin decreased the free formaldehyde content and increased bonding strength and toughness of the prepared phenol formaldehyde resin, especially after the introduction of lignin treated with plasma. (3) The introduction of alkali lignin led to high curing temperature for the prepared phenol formaldehyde resin, but that was reduced by the plasma processed alkali lignin. (4) The introduction of alkali lignin could also increase thermal stability of phenol formaldehyde resin, but that was modified by plasma processed alkali lignin was better than the unprocessed lignin. Based on the results, the plasma processed lignin was used to modify phenol formaldehyde resin, which could increase the strength and toughness of phenol formaldehyde resin significantly.
Keywords
Alkali lignin; plasma; phenol formaldehyde resin; bonding performance; tensile property