We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Fast Curing Bio-Based Phenolic Resins via Lignin Demethylated under Mild Reaction Condition.
- Authors
Jiongjiong Li; Jizhi Zhang; Shifeng Zhang; Qiang Gao; Jianzhang Li; Wei Zhang
- Abstract
Demethylation technique has been used to enhance lignin reactivity for preparation of phenolic resins. However, the demethylation efficiency and the demethylated lignin (DL) reactivity were still unsatisfactory. To improve the demethylation efficiency, alkali lignin was demethylated under different mild conditions using sodium sulfite as a catalyst. Lignin and DL were characterized by ¹H-NMR (nuclear magnetic resonance) and Fourier transform infrared (FT-IR) spectroscopy to determine the demethylation mechanism. With the demethylation of lignin, the methoxyl group content decreased from 1.93 m mol/g to 1.09 m mol/g, and the phenolic hydroxyl group content increased from 0.56 m mol/g to 0.82 m mol/g. These results revealed that methoxyl groups were attacked by SO32-, and some methoxyl groups were converted to phenolic hydroxyl groups by a nucleophilic substitution reaction, generating DL with high reactivity. The chemical properties of lignin-based phenolic resins were studied by 13C-NMR and FT-IR spectroscopy, and their physical properties were also investigated. The results indicated that lignin-based phenolic resins exhibited faster curing rate and shorter gel time. In addition, the bonding strength increased from 0.92 MPa to 1.07 MPa, and the formaldehyde emission decreased from 0.58 mg/L to 0.22 mg/L after lignin demethylated at the optimum condition.
- Subjects
PHENOLIC resins; LIGNINS; DEMETHYLATION; REACTIVITY (Chemistry); SODIUM sulfites
- Publication
Polymers (20734360), 2017, Vol 9, Issue 9, p428
- ISSN
2073-4360
- Publication type
Article
- DOI
10.3390/polym9090428