Date of Award

Summer 6-22-2025

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Chemical Engineering

First Committee Advisor

Douglas W. Bousfield

Second Committee Member

Jinwu Wang

Third Committee Member

Ling Li

Additional Committee Members

Mehdi Tajvidi

Colleen Walker

Abstract

The food packaging industry makes use of enormous quantities of plastic-based materials owing to their superior barrier properties. However, most of these materials are non-biodegradable and end up in landfills. Also, some tableware used to depend on PFAS to obtain the oil and grease resistant properties required by consumers. Cellulose nanofibrils (CNF) can potentially replace some types of plastics and give rise to the oil and grease barrier properties that consumers desire. Although the use of CNF as a layer could result in paperboards with good oil barrier properties but not good water resistance, the effect on barrier properties after being subjected to a thermoforming event is unclear in the literature. Drainage of CNF suspension onto paperboard is one possible way to obtain paperboards with a CNF film on the surface. Yet the drainage parameters are also not well characterized in the literature. This study characterized the drainage of CNF suspension onto paperboard and analyzed the effects of additives and treatment methods on the barrier properties of CNF coated paperboard and their ability to withstand a 3D dry thermoforming event. To enhance the water barrier iii properties of the CNF coated paperboard, different water-based hydrophobic additives were explored through surface and internal treatment methods. The effects of the additives and treatment methods on barrier properties were analyzed. The best formulation and treatment method were applied to a layer-structured paperboard to explore its ability to withstand the 3D dry thermoforming event for paper plate and tray production. The results of the CNF suspension drainage characterization revealed that the dewatering of CNFs follows a filtration model well on a small filtration device, with an R2 value greater than 0.98, and the developed model gave good CNF drainage predictions on a lab-scale sheet former. It was also revealed that incorporating a CNF layer on a paperboard through surface treatment not only confers robust oil resistance but also synergistically enhances water resistance when combined with a conventional water-resistant coating. In addition, the paperboards with a CNF layer withstood the thermoforming event and were successfully pressed into plates without rupturing, blistering, or severely cracking. The formed plates exhibited better oil resistance than two selected commercial paper plates.

Comments

Sustainable packaging, Paper plates

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