Nanocellulose, pectin and lignin biomimetic composite filaments by wet spinning

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Kemian tekniikan korkeakoulu | Master's thesis
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Renewable Materials Engineering
Degree programme
Master's Programme in Bioproduct Technology
Bio-based materials are central components for the success of the future bio-economy and to fulfil product demands, for example, those derived from wood components, including cellulose, hemicellulose, lignin, extractives, etc. In turn, they can potentially address many current societal needs. An effort within the field of biomimetics of wood fibres, as presented in this thesis, is the use of TEMPO-oxidized nanocellulose (TOCNF), pectin and alkaline lignin to synthesize composite filaments. Such effort is aimed to the development of high performance products with low environmental impact. The composite water-based dope, containing the cell wall components along with calcium salts, displayed shear thinning properties and their spinnability was in some ways related to the apparent viscosity that need to be further proved. It was shown that pectin gelation was necessary for producing filaments by the wet spinning technology. In order to gellify pectin, two types of calcium salts (CaCO3 and CaCl2) were applied. It was found that acetone as coagulation medium afforded better spinnability compared to ethanol. In addition, the mechanical properties of the obtained filaments were compromised if excess calcium carbonate was used. It turned out that filaments obtained by using CaCO3 for in-situ gelation showed similar mechanical properties as those from TOCNF. In contrast, CaCl2 applied for ex-situ gelation made the filaments to become elastic. Remarkably, regardless the type of pectin gelation used, lignin improved the mechanical properties of TOCNF-based filament, in both the dry and wet state. SEM imaging was used to determine the surface morphology of the filaments. Filaments from in-situ gelation had similar surface features as those from neat TOCNF while those from ex-situ gelation were different. Polyhedral particles from CaCl2 salts were identified on the surface of filaments obtained from ex-situ gelation. Finally, quartz crystal microgravimetry was applied to understand the interaction mechanism between TOCNF, pectin and lignin.
Rojas, Orlando
Thesis advisor
Cunha, Gisela
Lundahl, Meri
composite filaments, nanocellulose, pectin, lignin, TOCNF
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