Investigating Tempo-Oxidized Cellulose Nanofiber Lubricating Greases Using Microscopy, Rheology, and Tribology

Uhryn, Jackson John Luke

Investigating Tempo-Oxidized Cellulose Nanofiber Lubricating Greases Using Microscopy, Rheology, and Tribology

dc.contributor.advisor	Egberts, Philip
dc.contributor.advisor	Trifkovic, Milana
dc.contributor.author	Uhryn, Jackson John Luke
dc.contributor.committeemember	Johansen, Craig
dc.contributor.committeemember	Natale, Giovanniantonio
dc.date	2024-11
dc.date.accessioned	2024-05-09T20:29:38Z
dc.date.available	2024-05-09T20:29:38Z
dc.date.issued	2024-05-01
dc.description.abstract	Lubricating grease plays a significant role limiting the negative effects of friction and wear present in moving components across a multitude of industries and applications. However, current materials commonly used to formulate greases often pose environmental risks during operation and disposal efforts. Additionally, due to the complex colloidal structures that form the backbone of grease, a detailed understanding of underlying lubricating mechanisms remains elusive, especially if considering greases composed of nanoparticle constituents. This thesis focuses on using sustainable materials such as cellulose nanofibers and organically modified nanoclay to formulate lubricating grease. Special detail is given concerning formulation failures and successes highlighting the role of surface modification using oleic acid and interfacial stabilization from clay particles. The performance of these greases are systematically characterized using two forms of microscopy, laser scanning confocal microscopy and cryogenic scanning electron microscopy, to understand microstructure networking behavior that ultimately governs their response under mechanical stress. Rheological characterization is performed to quantitatively evaluate grease behavior under dynamic stress/strain. Lastly, tribological characterization is performed to evaluate friction and wear performance of formulated samples. Care has been taken to link all three avenues of characterization to help provide a more detailed understanding of underlying mechanisms governing these specific grease systems. It was observed that most greases are composed of networks between tightly held spheroid bundles of cellulose and oleic acid while clay interfacially adsorbs at the interface and prevents large scale aggregates from forming. However at high concentrations of cellulose and oleic acid (>10% and 0.75 OA:TOCN ratio, respectively), the dispersion effect is so great that agglomerates form bundle-like structures which significantly alter rheological and tribological responses. Rheological flow curves and amplitude sweeps indicate two main competing factors, aggregate size and number of interfacial connections, are responsible for differences in network dynamics. Overall morphology also plays an important role indicated by the high storage moduli obtained for fiber-like samples (≈ 35 kPa). Stribeck and steady sliding wear curves revealed excellent boundary lubrication coefficient of friction performance in the range of 0.05-0.10 for all samples courtesy of both oleic acid and nanoparticle surface activity/tribofilm generation. It also revealed interesting high wear behavior at high relative concentrations of oleic acid. For example, wear scar diameter roughly increases 6x at 0.75 OA:TOCN ratio compared to both 0.25 and 0.50 ratios.
dc.identifier.citation	Uhryn, J. J. L. (2024). Investigating tempo-oxidized cellulose nanofiber lubricating greases using microscopy, rheology, and tribology (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.
dc.identifier.uri	https://hdl.handle.net/1880/118666
dc.language.iso	en
dc.publisher.faculty	Schulich School of Engineering
dc.publisher.institution	University of Calgary
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subject	Tribology
dc.subject	Rheology
dc.subject	Confocal Microscopy
dc.subject	Grease
dc.subject	Sustainable
dc.subject.classification	Engineering--Mechanical
dc.subject.classification	Engineering--Chemical
dc.subject.classification	Engineering--Environmental
dc.title	Investigating Tempo-Oxidized Cellulose Nanofiber Lubricating Greases Using Microscopy, Rheology, and Tribology
dc.type	master thesis
thesis.degree.discipline	Engineering – Mechanical & Manufacturing
thesis.degree.grantor	University of Calgary
thesis.degree.name	Master of Science (MSc)
ucalgary.thesis.accesssetbystudent	I do not require a thesis withhold – my thesis will have open access and can be viewed and downloaded publicly as soon as possible.