Degree
Doctor of Philosophy (PhD)
Department
School of Renewable Natural Resources
Document Type
Dissertation
Abstract
In recent years, the rheological aspects of suspensions/emulsions applied by cellulose nanomaterials (CNMs) have been gained considerable interests due to high gel-forming properties ascribed by hydrophilicity, crystallinity, ease functionalization, and high aspect ratio. Introducing residual lignin in CNMs (LCNMs) seemed to be capable of achieving various advantages in the application of CNMs ascribed by hydrophobicity, binding effects, and abundant aromatic groups derived from complexity of lignin. This dissertation dedicates to the characterizations of (L)CNMs, and rheological properties of (L)CNMs applied fluids (i.e., suspension and emulsion). In the suspension system, the presence of lignin in LCNMs decreased gel strength, viscosity, and dynamic moduli in deformation conditions. The use of water-soluble biopolymers (e.g., xanthan gum and polyanionic cellulose) helped compensate the negative effect of lignin on rheological properties of LCNMs including gel strength, yield stress, and gelation properties. In bentonite water suspension system, CNMs helped bridge bentonite (BT) particles for enhanced rheological performance but adversely affected filtration properties by forming thicker filter cakes. LCNMs enhanced viscosity, yield stress, and gelation properties of the fluid with effectiveness varying with the actual lignin content in the system. Enhanced filtration performance was observed with the presence of lignin in LCNMs ascribed by its hydrophobic nature as well as the formation of more compact filter cakes. In saline conditions, CNMs suspensions exhibited salt-dependent increase in rheological properties whereas LCNMs suspensions were less affected. However, both (L)CNMs showed salt-dependent increase in fluid loss, especially in CaCl2 condition. In the emulsion system, O/W (65:35) diesel emulsions were successfully stabilized by LCNMs but not with CNMs which exhibited separated large fiber-flocs throughout external phase. High lignin content LCNMs gave rise to uniform droplet size without detection of flocs in biased phase. The surfactant, sucrose ester (SE), helped the stabilization of (L)CNM emulsion, reducing the size of oil droplets with more uniform distribution, and facilitating the dispersion of fiber components. The gel properties of (L)CNM/SE emulsions were reduced due to the presence of SE working as dispersant, however, rheological properties were highly dominated by the characteristics of (L)CNM components. Significant improvements in filtration performance with BT applied emulsions were achieved via applying (L)CNM/SE. Overall, this research highlights the synergistic effects of (L)CNMs with biopolymers and surfactant SE in enhancing the rheological properties and stability of suspensions and emulsions for diverse industrial applications, while the use of cost-effective and sustainable LCNMs retaining lignin provides potential for future fluid applications in various related industries.
Date
3-27-2025
Recommended Citation
Koo, Meen Sung, "Rheological, Interfacial, and Filtration Behavior of Lignocellulosic Nanomaterials in Suspension and Emulsion Drilling Fluids" (2025). LSU Doctoral Dissertations. 7018.
https://repository.lsu.edu/gradschool_dissertations/7018
Committee Chair
Wu, Qinglin
LSU Acknowledgement
1
LSU Accessibility Acknowledgment
1
Included in
Complex Fluids Commons, Petroleum Engineering Commons, Wood Science and Pulp, Paper Technology Commons