2.2 Uniform lignin for biobased thermosets
- Fatima-Zahra El Bouchtaoui
- Postdoc,
- Linköping University
- Co-author(s): Andrey Shatskiy, Lars A. Berglund, Peter Olsén
- Supervisor (PhD-students/postdocs): Peter Olsén
- Lignin represents the most abundant renewable aromatic resource and holds significant potential for the development of bio-based thermoset materials. However, its large-scale utilization remains limited due to pronounced chemical heterogeneity and uncontrolled reactivity, which complicate processability and reactivity control in polymer formulations. In this work, kraft lignin was chemically homogenized via hydroxyethylation with ethylene carbonate (EC) to generate uniform and highly functional intermediates suitable for thermoset synthesis. By varying the lignin-to-EC ratio, phenolic hydroxyl groups were selectively converted into aliphatic hydroxyl groups, providing a controlled platform for subsequent polymer modification. Comprehensive structural characterization of the resulting hydroxyethylated lignins (HEL) was conducted using FTIR and HSQC NMR, confirming successful grafting of hydroxyethyl moieties onto the lignin backbone. Quantitative ³¹P NMR analysis demonstrated complete conversion of phenolic hydroxyls and carboxylic acids, evidencing the effectiveness of the homogenization strategy. Molecular weight evolution determined by GPC indicated controlled structural modification following hydroxyethylation. Thermal analyses (TGA and DSC) revealed improved thermal behavior and enhanced processability compared to unmodified lignin. To assess industrial feasibility, the hydroxyethylation process was successfully upscaled from 1 g to 100 g without compromising structural homogeneity or thermal properties. The resulting uniform HEL is currently being explored in crosslinking formulations for the development of bio-based thermoset networks with tunable architectures. Overall, this work establishes a scalable and application-oriented strategy for transforming industrial lignin into uniform reactive building blocks suitable for green thermoset material development.
- Time of presentation: 9.20