Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
The aim of this project was to synthesize highly swelling hydrogels from wood hydrolysates, which are hemicellulose rich side products from industrial processes using wood as raw material. Hydrogels were successfully synthesized from one pure hemicellulose, O-acetyl-galactoglucomannan and two wood hydrolysates originating from spruce and birch wood. The hydrogels were synthesized in a three step procedure: synthesis of a coupling agent, grafting of vinyl functionality onto the hemicelluloses and finally crosslinking with acrylic acid (AA) or AA and 2-hydroxyethyl methacrylate (HEMA) as co-monomers. The degree of substitution (DSvinyl) was determined with 1H-NMR analysis and the inclusion of the co-monomers into the hydrogels was confirmed using FT-IR analysis. High equilibrium swellings (Qeq) in the region of 500 grams of water per gram of dry material were achieved. The DSvinyl of the hydrolysates was discovered to have a high impact on the Qeq while the effect of adding small amounts of HEMA, instead of only adding AA, was ambiguous. The inclusion of AA was found to have a large effect on the Qeq both from comparing with samples with high HEMA content in this study and compared to earlier published results from our division where no co-monomer or only HEMA was added. Using water as solvent in the crosslinking step was found to give higher Qeq than using DMSO. From the results it is concluded that hydrolysates can be used for creating highly swelling hydrogels and that further purification to increase the hemicellulose content may be unnecessary and perhaps even detrimental to the Qeq.
Place, publisher, year, edition, pages
hydrogel, hemicellulose, xylan, galactoglucomannan, acrylic acid, swelling, HEMA, absorbent.
IdentifiersURN: urn:nbn:se:kth:diva-150788OAI: oai:DiVA.org:kth-150788DiVA: diva2:745010