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Biorefinery lignin nanoparticles analysis by asymmetric flow field-flow fractionation (AF4) system
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School of Chemical Engineering |
Master's thesis
Electronic archive copy is available via Aalto Thesis Database.
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en
Pages
52
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Abstract
Lignin nanoparticles (LNPs) represent a promising way to transform the natural polymer lignin into uniform materials for high-performance applications. Several factors affect the properties of LNPs, especially their size and size distribution. Hence, accurate size determination is significant for LNPs utilization. The objectives of this research were to study the effect of molar mass on the size of LNPs, to characterize LNPs using asymmetric flow field-flow fractionation and to compare the results with the traditional size characterization techniques such as dynamic light scattering (DLS) and scanning electron microscope (SEM). LNPs were prepared by solvent shifting using THF-water with a lignin concentration of 2.2 wt% and were characterized by DLS, SEM and AF4. LNPs derived from higher Mw lignin (Mw of 16170 g/mol) resulted in smaller particles with diameters of 63 nm, whereas lower Mw lignin (3485 g/mol) produced larger particles with diameters of 977 nm. This trend was consistent for both hardwood and softwood lignin. Additionally, LNPs derived from softwood were smaller than those from hardwood. The analysis using AF4 technique demonstrated the ability to characterize the size range of LNPs effectively. However, there are many parameters that need to be considered in operating the AF4 system such as concentration of the sample, injection volume, crossflow gradient, and channel flow rate.
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Supervisor
Hummel, MichaelThesis advisor
Pitkänen, LeenaNousiainen, Paula