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In this research work, a coated paper was prepared with poly (butylene adipate-co-terephthalate) (PBAT) film to explore its use in eco-friendly food packaging. The paper was coated with PBAT film for packaging using hot pressing, a production method currently employed in the packaging industry. The coated papers were evaluated for their structural, mechanical, thermal, and barrier properties. The structural morphology and chemical analysis of the coated paper confirmed the consistent formation of PBAT bi-layered on paper surfaces. Surface coating with PBAT film increased the water resistance of the paper samples, as demonstrated by tests of barrier characteristics, including the water vapor transmission rate (WVTR), oxygen transmission rate (OTR), and water contact angle (WCA) of water drops. The transmission rate of the clean paper was 2010.40 cc m−2 per 24 h for OTR and 110.24 g m−2 per 24 h for WVTR. If the PBAT-film was coated, the value decreased to 91.79 g m−2 per 24 h and 992.86 cc m−2 per 24 h. The hydrophobic nature of PBAT, confirmed by WCA measurements, contributed to the enhanced water resistance of PBAT-coated paper. This result presents an improved PBAT-coated paper material, eliminating the need for adhesives and allowing for the fabrication of bi-layered packaging. [ABSTRACT FROM AUTHOR]

Enhancing paper hydrophobicity is of key importance for many paper-based applications. Fatty acids or vegetable oils and their derivatives replace environmentally harmful conventional coating materials but still require challenging chemical reactions for covalent attachment onto paper. Here, we show that simple storage of olive oil-coated cotton linter paper at 70 °C and subsequent Soxhlet extraction is able to endow paper with hydrophobic properties, reaching water contact angles above 130°. In-depth chemical and morphological analytics show the relevance of temperature and air accessibility during the aging process compared with aging at ambient temperature and under the exclusion of oxygen, underlining the importance of assessing a coating's long-term performance and stability under diverse storage conditions. Simple storage of vegetable oil-coated paper at elevated temperatures followed by extraction proves to be an easy way to produce stable covalently attached hydrophobic paper coatings with exceptionally low coating amounts. [ABSTRACT FROM AUTHOR]

Cellulosic-based materials such as hemp fabric and paper have combined characteristics of renewability, biodegradability, flexibility, and recyclability. However, regular products are not suitable for use in unconventional applications due to inherent limitations, and accordingly, enabling new capabilities is a necessity. To this end, the conversion of regular hemp fabric and paper into high-strength products with hydrophobic function via surface engineering was explored. The fluorinated waterborne polyurethane (FWPU) emulsions were first synthesized as functional coatings by in-situ polymerization. The structure and properties of the FWPU emulsion and film were characterized by FTIR, XRD, SEM, TG, and XPS. The results showed that the grafting of perfluorooctanol imparts WPU film excellent hydrophobicity, and the water contact angle increases from 71.2° to 105.9°. After the FWPU coating, the water contact angles of the hemp fabric and paper increase from 0° to 117.1° and 112.8°, respectively. Quite encouragingly, the coating generation of waterborne polyurethane-derived functional additives led to the increase of mechanical strength by more than 23% and 82%, in the case of qualitative filter paper and hemp fabric. Meanwhile, the folding strength of filter paper is increased by 132 times. Overall, this functionalized waterborne polyurethane coating would direct paper and hemp fabric toward diversified applications. [ABSTRACT FROM AUTHOR]

Flow and spontaneous imbibition phenomena in porous media are important for various industrial applications, including printing and medical lateral flow assays. Their quantitative characterization is important to better understand and select the appropriate raw materials. However, standard methods often require time-consuming tests, and/or expensive equipment. Different time scales must be considered, limiting the range of possible characterization tools. A novel experimental approach based on image analysis for characterizing spontaneous imbibition processes is presented. Hence, ultra-fast diffusion may be quantitatively characterized. Models are issued from the literature to consider physical phenomena at small (milliseconds) and medium range (seconds) of time scales. The obtained experimental data fit with theoretical results, providing valuable insights into the understanding of fluid flow behavior at different time scales. Furthermore, the identification of some physical properties for either the fluid, or the substrate, based on the theoretical models are possible, as the contact angle, which remains to be otherwise challenging. This study contributes to bridging the gap between spontaneous imbibition and capillary phenomena at different time scales, their modeling, and a characterization of material and/or fluid properties paving the way for enhanced understanding and control of fluid behavior in porous media. Different papers are considered to illustrate the method. [ABSTRACT FROM AUTHOR]