Date of Award

Fall 12-2021

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Forest Resources

Advisor

Mehdi Tajvidi

Second Committee Member

Douglas J. Gardner

Third Committee Member

Douglas W. Bousfield

Abstract

Cellulose nanofibrils (CNFs) and lignin-containing cellulose nanofibrils (LCNFs) have excellent binding properties with lignocellulosic materials such as wood particles, cellulose fibers, and other particles. They also have excellent oil and grease barrier properties. A novel application by utilizing the binder and barrier properties of CNF and LCNF has been proposed. In this study, multi-layer oil-resistant food serving containers were made using cellulose nanofibril coated wood flour composites. Composites were made with different formulations by using LCNF from old corrugated containers (OCC) at different fines content and CNF at 20, 30, and 40% binder content combined with wood particles. LCNF and CNF from unbleached and bleached kraft pulp respectively, were used as the coating layer for the composites. 90% fine CNF, 70% fine, or 90% fine LCNF-OCC suspensions were homogeneously dispersed in water using ultrasound energy to produce suspensions at 3 wt.% solids and then they are mixed with wood particles. The coating layer of LCNF or CNF suspensions was produced in the same way at 0.2 wt.% solids without the addition of wood particles. The mixture was then deposited on a paper substrate using vacuum filtration. After filtration of water, the top layer was deposited on the base layer and filtered. The wet materials were then taken out and dried by pressing in a hot press at 150 °C and 1.5 kPa pressure. The surface, mechanical, thermal, and barrier properties of the composites were investigated and compared with a commercial container. It was determined that composites with 70% fine LCNF-OCC at 30% binder content with LCNF coating layer were the most cost-effective formulation with excellent oil and grease resistance and mechanical and thermal properties to be used for food serving applications. Subsequently, the water barrier properties of the composites with 70% fine LCNF-OCC at 30% binder content and CNF or LCNF coating layer were investigated by water absorption test for 600 s, 1200 s, and 1800 s. Mechanical properties of the composites after absorption of water for different test times were determined by the ‘wet’ flexural test. It was determined that both CNF and LCNF coated composites had poor water barrier properties compared to the commercial container. The addition of 1% alum to the coating layer of CNF or LCNF composites significantly improved their water barrier properties. It was determined that LCNF + 1% alum coated composites had comparable water resistance and higher ‘wet’ mechanical properties compared to the commercial containers. Recyclability of the composites was assessed based on mechanical and oil and grease barrier properties. It was found out that the composites were recyclable, and the recycled composites had the required mechanical and oil and grease barrier properties to be used for food serving applications. Overall, the LCNF + 1% alum coated composites exhibited excellent mechanical and barrier properties and can be considered as an alternative for water and oil-resistant commercial food serving containers.

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