Drying temperature effect on the characteristics of cationically polymerized kraft lignin

• Published in: International journal of biological macromolecules 2024-11, Vol.280 (Pt 3), p.135935, Article 135935
• Main Authors: Bacchus, Ameena, Fatehi, Pedram
• Format: Article
• Language: English
• Subjects: Drying; Lignin; Sustainable materials
• ISSN: 0141-8130; 1879-0003; 1879-0003
• DOI: 10.1016/j.ijbiomac.2024.135935

In this work, the effect of drying temperature (55–130 °C) on the properties of kraft lignin (KL) polymerized with [2-(methacryloyloxy)ethyl] trimethyl ammonium chloride, as a sustainable polymer (KLM) was investigated. KLM exhibited a 3-fold drop in charge density and a 10 % reduction in water solubility. These alterations were found to be associated with both chemical and physical changes determined by NMR and XPS analyses. At 55 °C, chain interactions were predominant due to electrostatic interactions amongst the pMETAC chains with the electronegative atoms present in KL. At 80, 105, and 130 °C drying temperatures, hydrolysis reactions predominated. The KLM polymer possessed, comparatively, a lesser resistance to thermal degradation than KL, and the KLM polymer had a more uniform thermal degradation behavior across the drying temperatures. Glass transition temperature, Tg, was shown to be comparable for KL across the various drying temperatures. KLM, however, showed an increasing trend as drying temperature increased, up to 130 °C, at which point Tg dropped due to KL degradation. Therefore, the drying temperature has a significant impact on the properties of kraft lignin and its cationic polymerized derivative, and it should be carefully selected to minimize the undesired changes in lignin properties.