PAPER making! FROM THE PUBLISHERS OF PAPER TECHNOLOGY INTERNATIONAL ® FROM THE PUBLISHERS OF PAPER TEC Volume 11, Number 3, 2025
Cellulose hybrid coatings with enhanced moisture nanofibril-based
barrier properties JINGXUAN ZHANG & JEFFREY P. YOUNGBLOOD
Cellulose nanomaterials have garnered significant attention as the next generation of environmentally friendly packaging materials because of their abundance, biodegradability, low density, superior mechanical properties, and excellent oxygen barrier characteristics. However, due to their hydrophilic nature, CNMs exhibit poor water barrier properties at high humidity conditions, which limits their potential applications. Our previous research has successfully incorporated CNF with CMC and coated the CNF/CMC coating on molded pulp trays for food packaging, but the barrier properties of CNF/CMC were weakened under high humidity conditions due to the hydrophilic nature of the coating and plasticization effect of the water molecules during the permeation process. In this study, we enhanced the water barrier properties of CNF-based coatings on molded pulp trays by chemically modifying the CNF through crosslinking with polyamide-epichlorohydrin (PAE), the incorporation of Cloisite-Na + nano-clay, and the addition of polyvinyl alcohol (PVA). This formulation further improved the water vapor transmission rate (WVTR) in both wet-cup and dry-cup conditions, showing 40.5% in wet WVTR and 89.2% in dry WVTR values compared to unmodified CNF/CMC coatings. The chemical modification also helped enhance oxygen barrier performance, in which OP decreased from 6.48 x 10 -15 cm 3 [STP] cm cm -2 s -1 Pa -1 to 2.31 x 10 -15 cm 3 [STP] cm cm -2 s -1 Pa -1 . A reduction in Cobb value from 137 ± 9 g m -2 to 56.3 ± 4.4 g m -2 was also observed. The formulated CNF-coated MP trays maintained the same #12 oil and grease resistance level as the unformulated ones. Mechanical testing proved that the formulated CNF coated tray samples showed 23.3% increase in ultimate tensile strength, 96.7% increase in strain at failure, but 37.6% decrease in Young’s modulus. These results demonstrate that our chemically modified CNF coatings offer a promising sustainable alternative to conventional synthetic packaging materials, particularly for food packaging applications requiring enhanced barrier properties at high humidity conditions. Contact information: School of Materials Engineering, Purdue University, West Lafayette, IN, 47907, USA. Mater. Adv ., 2025, 6, 2833–2844 https://pubs.rsc.org/en/content/articlelanding/2025/ma/d4ma01276c Creative Commons Attribution 4.0 License
The Paper Industry Technical Association (PITA) is an independent organisation which operates for the general benefit of its members – both individual and corporate – dedicated to promoting and improving the technical and scientific knowledge of those working in the UK pulp and paper industry. Formed in 1960, it serves the Industry, both manufacturers and suppliers, by providing a forum for members to meet and network; it organises visits, conferences and training seminars that cover all aspects of papermaking science. It also publishes the prestigious journal Paper Technology International ® and the PITA Annual Review , both sent free to members, and a range of other technical publications which include conference proceedings and the acclaimed Essential Guide to Aqueous Coating .
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Article 1 – Nanocellulose Coatings
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