文献类型：期刊文献

英文题名：Demethylation of Alkali Lignin with Halogen Acids and Its Application to Phenolic Resins

作者：Wang, Hao[1,2] Eberhardt, Thomas L.[3] Wang, Chunpeng[4] Gao, Shishuai[4] Pan, Hui[1,2]

第一作者：Wang, Hao

通信作者：Pan, H[1];Pan, H[2]

机构：[1]Nanjing Forestry Univ, Jiangsu Coinnovat Ctr Efficient Proc & Utilizat F, 159 Longpan Rd, Nanjing 210037, Jiangsu, Peoples R China;[2]Nanjing Forestry Univ, Coll Chem Engn, 159 Longpan Rd, Nanjing 210037, Jiangsu, Peoples R China;[3]USDA, Forest Prod Lab, One Gifford Pinchot Dr, Madison, WI 53726 USA;[4]Chinese Acad Forestry, Inst Chem Ind Forestry Prod, Nanjing 210042, Jiangsu, Peoples R China

年份：2019

卷号：11

期号：11

外文期刊名：POLYMERS

收录：;EI(收录号：20194807757772);Scopus(收录号：2-s2.0-85075547793);WOS:【SCI-EXPANDED(收录号:WOS:000503279200044)】；

基金：The authors are grateful for the financial support by National Natural Science Foundation of China (No. 31770631), the project of the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institution, China and Top-notch Academic Programs Project of Jiangsu Higher Education Institutions (TAPP) of China (PPZY2015C221).

语种：英文

外文关键词：alkali lignin; demethylation; halogen acids; phenolic resin

摘要：Lignin, a byproduct from the chemical processing of lignocellulosic biomass, is a polyphenolic compound that has potential as a partial phenol substitute in phenolic adhesive formulations. In this study, HBr and HI were used as reagents to demethylate an alkali lignin (AL) to increase its hydroxyl content and thereby enhance its reactivity for the preparation of phenolic resins. Analyses by FT-IR, H-1-NMR and 2D-NMR(HSQC) demonstrated both a decrease in methoxyl groups and an increase in hydroxyl groups for each demethylated lignin (DL). In addition, the molar amounts of phenolic hydroxyls, determined by H-1-NMR, increased to 0.67 mmol/g for the HI-DL, and 0.64 mmol/g for the HBr-DL, from 0.52 mmol/g for the AL. These results showed that HI, a stronger nucleophilic reagent than HBr, provided a higher degree of AL demethylation. Lignin-containing resins, prepared by copolymerization, met the bonding strength standard for exterior plywood with DL used to replace as much as 50 wt.% of phenol. The increased hydroxyl contents resulting from the lignin demethylations also imparted faster cure times for the lignin-containing resins and lower formaldehyde emissions. Altogether, the stronger nucleophilicity of HI, compared to HBr, impacted the degree of lignin demethylation, and carried through to measurable differences the thermal properties and performance of the lignin-containing PF resins.