Oil and grease-resistant molded fiber containers produced by partial substitution of wood pulp with wood particles enabled by cellulose nanofibrils

Molded fiber products are regaining popularity for food service applications due to growing concerns about plastic pollution and environmental sustainability. However, to render molded fiber products water and grease resistant, per- and polyfluoroalkyl substances are usually added. In this work, we have demonstrated that cellulose nanofibrils (CNFs) can play a dual role in molded fiber products, both as a binder and as a grease resistant layer. The objective of this work was to produce paper plates via a thermoforming process by hybridizing conventional bleached Kraft pulp (BKP) with lignocellulosic residues such as wood flour (WF) or thermomechanical pulp, using CNFs as a binder. Different formulations were prepared to screen the paper plate formulations and determine the optimal weight percentage ratio of raw materials based on the mechanical properties (tensile and flexural) of the product. The order in which lignocellulosic fibers were added was investigated prior to the experiments and found to have no impact on the mechanical properties of the paper plates. Replacing 35% of BKP with WF and using 10% CNF as a binder resulted in a 90–130% increase in tensile and flexural properties of the paper plates compared to control paper plates made from BKP. Paper plates laminated with 40 g/m² CNF exhibited a good grease barrier (Kit 12), a Cobb value of 36 ± 4 g/m², and tear resistance of 14 ± 4.0 (N/mm), and had a smooth surface confirmed through SEM analysis.