| 1. |
- Gowda, V. Krishne, et al.
(författare)
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Nanofibril Alignment during Assembly Revealed by an X-ray Scattering-Based Digital Twin
- 2022
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 16:2, s. 2120-2132
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Tidskriftsartikel (refereegranskat)abstract
- The nanostructure, primarily particle orientation, controls mechanical and functional (e.g., mouthfeel, cell compatibility, optical, morphing) properties when macroscopic materials are assembled from nanofibrils. Understanding and controlling the nanostructure is therefore an important key for the continued development of nanotechnology. We merge recent developments in the assembly of biological nanofibrils, X-ray diffraction orientation measurements, and computational fluid dynamics of complex flows. The result is a digital twin, which reveals the complete particle orientation in complex and transient flow situations, in particular the local alignment and spatial variation of the orientation distributions of different length fractions, both along the process and over a specific cross section. The methodology forms a necessary foundation for analysis and optimization of assembly involving anisotropic particles. Furthermore, it provides a bridge between advanced in operandi measurements of nanostructures and phenomena such as transitions between liquid crystal states and in silico studies of particle interactions and agglomeration.
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| 2. |
- Wang, R., et al.
(författare)
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Unexpected Gelation Behavior of Cellulose Nanofibers Dispersed in Glycols
- 2022
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Ingår i: Macromolecules. - : American Chemical Society. - 0024-9297 .- 1520-5835. ; 55:21, s. 9527-9536
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the gelation behavior of TEMPO-oxidized wood-based cellulose nanofiber (CNF) suspensions in two different glycols, ethylene glycol (EG) and propylene glycol (PG), was investigated near the overlap concentration and compared with that of aqueous CNF suspensions. The flow property of these non-aqueous and aqueous CNF suspensions was characterized by rheological, UV-vis, and rheo-optical techniques. It was found that the CNF(PG) suspensions exhibited stirring-reversible gelation behavior, where gelation could be induced simply by resting (i.e., prolonged holding time). However, this behavior was not observed for CNF(EG) and CNF(aq) suspensions. Higher temperature and higher CNF concentration could accelerate the gelation process of CNFs in PG, but no large-scale phase separation was detected by the optical techniques. Our study suggests that the reduced hydrophilic attraction between CNFs in PG is the main driving force for forming CNF-rich micro-domains, yielding a physically crosslinked network. This study suggests that the choice of solvent can be used to tailor and control the flow behavior of CNF suspensions, leading to designs of new cellulose-enabled nanocomposites for varying applications.
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