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Producing the biobased films of tomorrow : Nanocellulose dewatering with non-confined mechanical pressing

Cellulose Nano Fibrils (CNFs) can be extracted from wood and other plants. These CNFs are expected to play a large roll in future materials owing to their interesting properties and biobased nature. In this project, dewatering of gels made from CNF by non-confined mechanical pressing has been studied. A CNF suspension was gelled by the addition of HCl at pH 2 to form gel cakes and then pressed mechanically. The goal was to find the pressure limits of the gel cakes for different starting concentrations, in weight percentage [wt%], of CNF to optimize the pressure used when dewatering CNF gels. The non-confined pressing was achieved via the useof a Zwick/Roell Torsion multi-axis testing system. Gel cakes were pressed until a pressing equilibrium was reached. Equilibrium was reached when compression was less than 0.01 mm per 100 seconds. Gel cakes were frozen with liquid N2, freeze-dried, and analysed with Scanning Electron Microscopy (SEM). The results observed from the pressing data showed that gel cakes with higher CNF starting concentrations could survive higher pressures. Using the highest pressure available, at the pressure limit, yielded both the shortest run time and the highest dryness content. SEM imaging showed that the compression of the gel cakes starts at the surfaces and continuous inwards through the bulk. The mechanical pressure creates sheets of CNF both vertically and horizontally. By plotting the starting concentrations vs applied pressure a limit map with pressure regions could be created. From the limit map further optimization can be achieved to shorten the dewatering process of the CNF gels.

Identiferoai:union.ndltd.org:UPSALLA1/oai:DiVA.org:uu-527454
Date January 2024
CreatorsRoos, John Eric
PublisherUppsala universitet, Nanoteknologi och funktionella material
Source SetsDiVA Archive at Upsalla University
LanguageEnglish
Detected LanguageEnglish
TypeStudent thesis, info:eu-repo/semantics/bachelorThesis, text
Formatapplication/pdf
Rightsinfo:eu-repo/semantics/openAccess
RelationUPTEC K, 1650-8297 ; 24007

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