Cationized tannins as a retention aid for cellulose fibre Daniel Bäckström   Abstract The purpose of this study was to try cationized tannins as a potential retention aid for cellulose fibres in papermaking and to compare their potential with starch which already is commonly used. The study also tried to find other advantages with using tannins as a retention aid. Synthetic retention aids like polyacrylamide is also commonly used in papermaking, with good results. Synthetic retention aids are long-lived and their long-term effect on the environment is unkown. Therefore the demands are growing for more bio-degradable products. Measure glass, turbidity removal and COD was used in this study to analyse tannins as a retention aid on cellulose fibres. The results showed very clear water and a higher flocculation compared to the glass without tannins. 500 ppm tannins added to recycled fibres showed the best results for both flocculation and clear water as well as the highest turbidity removal, from 85 to 24 FTU. Different tannins was used in this study, and Tanfloc from the bark of the Acacia tree showed the best results. In the comparison between cationized starch and Tanfloc, Tanfloc showed better results for both flocculation and clearer water. Tannins shows potential as a retention aid for cellulose fibres, but clearer water and higher flocculation is not enough to determine tannins as a retention aid. They also show potential to solve the problem with bacteria in paper making because of their antibacterial effect. However, more tests and other methods needs to be done to show tannins potential as a retention aid.

京都大学 / 新制・論文博士 / 博士(医学) / 乙第13462号 / 論医博第2249号 / 新制||医||1055(附属図書館) / (主査)教授 萩原 正敏, 教授 松田 秀一, 教授 齊藤 博英 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

Yes / Antibacterial hydrogels have been intensively studied due to their wide practical potential in wound healing. However, developing an antibacterial hydrogel that is able to integrate with exceptional mechanical properties, cell affinity, and adhesiveness will remain a major challenge. Herein, a novel hydrogel with antibacterial and superior biocompatibility properties was developed using aluminum ions (Al3+) and alginate− dopamine (Alg-DA) chains to cross-link with the copolymer chains of acrylamide and acrylic acid (PAM) via triple dynamic noncovalent interactions, including coordination, electrostatic interaction, and hydrogen bonding. The cationized nanofibrillated cellulose (CATNFC), which was synthesized by the grafting of long-chain quaternary ammonium salts onto nanofibrillated cellulose (NFC), was utilized innovatively in the preparation of antibacterial hydrogels. Meanwhile, alginate-modified dopamine (Alg-DA) was prepared from dopamine (DA) and alginate. Within the hydrogel, the catechol groups of Alg-DA provided a decent fibroblast cell adhesion to the hydrogel. Additionally, the multitype cross-linking structure within the hydrogel rendered the outstanding mechanical properties, self-healing ability, and recycling in pollution-free ways. The antibacterial test in vitro, cell affinity, and wound healing proved that the as-prepared hydrogel was a potential material with all-around performances in both preventing bacterial infection and promoting tissue regeneration during wound healing processes. / This work was supported by the National Natural Science Foundation of China (32070826 and 51861165203), the Chinese Postdoctoral Science Foundation (2019M650239, 2020T130762), the Sichuan Science and Technology Program (2019YJ0125), the State Key Laboratory of Polymer Materials Engineering (sklpme2019-2-19), the Chongqing Research Program of Basic Research and Frontier Technology (cstc2018jcyjAX0807), Chongqing Medical Joint Research Project of Chongqing Science and Technology Committee & Health Agency (2020GDRC017), and the RCUK China-UK Science Bridges Program through the Medical Research Council, and the Fundamental Research Funds for the Central Universities.