PAPER making! g! FROM THE PUBLISHERS OF PAPER TECHNOLOGY INTERNATIONAL ® Volume 11, Number 1, 2025
numerically investigated. The results showed that the drying time was reduced by 25.0 – 37.5% and the average temperature increased by 4.8 –7.3 °C as the microwave power density enhanced from 9 to 15 W/g. The simulated spatial field distributions revealed the presence of two distinct hot spots on the surface of MPP, characterized by higher electric field strength and elevated temperatures, with the right hot spot being more pronounced. The transient distributions indicated that heat migrated from the hot spots to the edges of the MPP, while the distribution of moisture content presented an inverse relationship to the temperature field. Additionally, it was observed that the maximum temperature reached 107 °C at 15 W/g, which could potentially result in material cracking or deformation. To address this issue, a variable power drying scheme that could reduce the drying time by 10% was proposed. The developed model provides a comprehensive understanding of the coupled heat and moisture transfer occurring in the MPP microwave drying process. “Pistachio Shell Powder as an Additive in Molded Pulp Products”, Leila Fereidooni , Ana Rita C. Morais, Richard Venditti, Marcel Kropat, Jeff Shook & Mark B. Shiflett, BioResources , Vol.20(2), 2025. Molded pulp products (MPP) products can accommodate a variety of fiber types and additives, including agricultural residues. This work showed the industrial scale production of molded pulp food trays made of double lined kraft clipping fibers with the addition of pistachio shell (PS) powder at levels from 5 to 30 wt% and evaluated the mechanical and barrier properties of the trays. The PS powder used to make the trays was ground using an impact mill and a cryo mill to a D50 of approximately 50 microns. Tray compression strength was tested to simulate the wrapping of food trays with plastic wrap. Additionally, the tray material’s basis weight, thickness, density, tensile strength, short span compressive strength, and absorptiveness were determined. The results showed that compared to the control tray sample, the trays containing the cryo-milled pistachio powder had essentially the same engineering properties as the control trays without PS. For the trays made with the impact-milled powder, the tensile strength, bending resistance, and compressive strength increased relative to the control 11.3%, 6.2%, and 13.5%, respectively. The study demonstrates a method to evaluate the incorporation of alternative materials into pulp molded products. “Oil and grease -resistant molded fiber containers produced by partial substitution of wood pulp with wood particles enabled by cellulose nanofibrils”, Mamoona Raheem, Carl P. Tripp & Mehdi Tajvidi, Cellulose , Vol.32, pp.1851 – 1866, 2025. 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 40g/m 2 CNF exhibited a good grease barrier (Kit 12), a Cobb value of 36 ± 4 g/m 2 , and tear resistance of 14 ± 4.0 N/mm, and had a smooth surface confirmed through SEM analysis.
Technical Abstracts
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