Lignin is now considered one of the most promising renewable resource, formed in nature by the radical polymerization of p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol, bearing p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) units, respectively. It serves as an alternative feedstock for the synthesis of renewable chemicals and polymers. Particularly, the development of lignin-based epoxy resins is a promising way to use it as a substitute for petroleum-based epoxies.<br/>In this study, we focus on the structural characterization of various lignins, such as Kraft lignin (Indulin AT, US), lignosulfonate lignin (Borresperse CA, US, and Borresperse 3A, US) and Organosolv lignin. The functional groups of the different lignin structures were analyzed by Fourier-transform infrared spectroscopy (FTIR), pyrolysis–gas chromatography-mass spectrometry (Py-GCMS), Heteronuclear single-Quantum correlation (2D HSQC), Phosphorus-31 nuclear magnetic resonance spectroscopy (31P NMR) and methoxy group content. Additionally, the thermal properties of the lignin were studied using differential scanning calorimetry and thermogravimetric analysis. The combined data provided valuable information on the structure and composition of the utilized lignins. To determine the average molar mass (Mw) and polydispersity (PD) of the lignin macromolecule, gel permeation chromatography (GPC) was utilized. Finally, we worked on the epoxidation of lignin through various reaction paths. This reaction was monitored by FTIR and 31P NMR.

Physico-chemical characterization of lignins from different sources for the synthesis of lignin based epoxy resins

2019 Spring National Meeting

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