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Zhou, Chenli

University of British Columbia

The demand for biodegradable molded pulp packaging materials has increased significantly due to the ban on single-use plastics in many countries. Current dominant commercial molded pulp food containers impart oil resistance with the addition of Per- and Polyfluoroalkyl Substances (PFAS), but recent research has confirmed the toxicological effects of PFAS on human health. This strongly motivates the industry to find an alternative oil repellent that is food-grade safe, environmentally-friendly and effective. This thesis investigated a new modified starch-based oil repellent (SOR) as a wet-end additive. Non-wood fibers were selected to be the substrate to quantify the effects of additives due to the advantages of low cost, rapid renewability and abundant resources. The fiber morphology of bamboo, bagasse, wheat straw and miscanthus grass was characterized to select the suitable fibers for producing packaging materials. Due to the short fiber length and high coarseness, miscanthus grass was excluded from the subsequent experiments. Fiber blend effects on tensile index and paper porosity for bamboo, bagasse and wheat straw were investigated. Five commercial molded pulp food containers were characterized in terms of their physical and mechanical properties to benchmark laboratory fabrication and testing of prototypes. The quantitative effects of two key performance additives: alkyl ketene dimer (AKD) and SOR, and fiber blend were studied through mechanical and barrier property tests. I concluded that: (1) Bamboo fiber has the longest fiber length and can act as a reinforcement by mixing with short wheat straw and bagasse fibers; (2) Bamboo and bagasse fibers with thin cell wall can facilitate the formation of dense fiber network structure, which are better suited for food packaging manufacturing; (3) High sheet density and thin fiber cell wall are two critical factors to reduce the liquid penetration for paper substrate; (4) AKD and SOR are effective to provide water and oil resistance for molded pulp products, but the current bio-based oil repellent appears to not perform as well as PFAS additives; (5) Fiber blend can lead to more synergistic interaction with performance additives and result in better overall mechanical and barrier properties.

Text

2023-09-30

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/82388

Forestry

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/