Wax Coatings for Paper Packaging Applications: Study\nof the Coating Effect on Surface, Mechanical, and Barrier Properties

The aim of this study\nwas to comprehensively assess the effect\nof environmentally friendly wax coatings, including beeswax, soywax,\nTopScreen biowax, and a conventional water-based emulsion wax on paper\nfor food packaging applications. A food-grade paper was bar-coated\nwith a single layer of molten wax on both sides, varying in the coating\nweight, coating thickness, and wax type. Waxes were thoroughly characterized\nin terms of their functional groups, thermal properties, degree of\ncrystallinity, and crystal morphology using polarized optical microscopy.\nThereafter, wax-coated papers were studied in terms of their morphological,\nmechanical, and water vapor barrier properties. Moreover, the water\nand oil contact angles were measured to determine the resistance of\nwax-coated papers to moisture and grease penetration. Wax coatings\nrepresent 10–25% of the weight of the coated paper, with a\ncoating thickness of 5–10 μm. Scanning electron microscopy\nimages showed that waxes penetrated the cellulosic fibers of the paper,\nthereby effectively reducing its porous structure. Water and oil contact\nangles of the uncoated paper increased after the wax coating. Among\nthe four waxes, beeswax-coated paper was characterized as having superior\ncapability in improving the water vapor barrier of the uncoated paper\n(by ∼77%). While the percentage elongation at break (EB %)\ndecreased for all four wax-coated papers, tensile strength (TS) and\nelastic modulus (<i>E</i>) increased, with beeswax showing\nthe highest percent improvement in TS (by ∼26%) and <i>E</i> (by ∼46%). Our results suggest that paper surface\nmodification through ecofriendly wax coatings can be utilized as an\nalternative for petroleum-based paper coating materials for food packaging\napplications.