The lignin is an abundant biopolymer and kraft lignin is mostly a byproduct of the pulping industry. The hydroxymethylation reaction of softwood kraft lignin was studied with a straightforward differential scanning calorimetry (DSC) method, which can depict the reactivity of lignin. Paraformaldehyde was used as the formaldehyde source because of its simple composition and easy usability. Alkaline oxidative depolymerization was studied for the activation of softwood kraft lignin. The changes in structure and reactivity were analyzed using NMR and DSC methods and mass spectrometry. The simultaneous hydroxymethylation of softwood kraft lignin and phenol was investigated to detect methylolation and methylene bridge formation. Methylolated lignin materials in the phenol-formaldehyde resins provide a route to return lignin in plywood to the original wood environment.
The doctoral dissertation of MSc Hanna Paananen, entitled Activation reactions of the softwood kraft lignin will be examined at the Faculty of Science and Forestry on the 10th of December online. The opponent in the public examination will be Professor Ilkka Kilpeläinen, University of Helsinki, and the custos will be Professor Emerita Tuula Pakkanen, University of Eastern Finland. The public examination will be held in Finnish.
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