Bio-inspired hydrophobicity in cellulose nanopaper via thermal-induced phase separation of beeswax: A new strategy to develop sustainable food packaging materials and its service life prediction

Abstract

In this study, a hydrophobic cellulose nanopaper was developed by inducing hydrophobicity via the cost-effective and eco-friendly thermal-induced phase separation (TIPS) technique of beeswax. The resultant material suggests huge potential in food packaging applications due to the reduced water-vapour transmission rate (WVTR) and oxygen permeability, which is highly desirable in the current scenario. The beeswax adheres to the cellulose nanofiber through hydrogen bonding and hydrophobic-hydrophobic interactions. The fabricated hydrophobic cellulose nanopaper was characterized by FTIR, SEM, XRD, TGA and UTM. The beeswax-modified cellulose nanopaper (BCNP) showed a water contact angle of 119° and tensile strength of 28.5 MPa. The TIPS of beeswax in the CNP resulted in the fine coating of beeswax, which subsequently led to a substantial reduction in the water vapour transmission rate (1.8 (g/h.m2)) and oxygen permeability (38 Barrer), suggesting that the fabricated BCNP could be an effective packaging material for foodstuffs. The biodegradability study of the material has also been investigated via soil burial tests. The surface area and pore size of the material were analyzed by using BET analysis. The fabricated material has the ability to efficiently preserve the tomato fruit at an ambient temperature. We also investigated the service life of CNP and bee wax-coated CNP using the Arrhenius equation, substituting the tensile strength values obtained during the hygrothermal ageing studies. Therefore, the fabricated packaging material developed from hydrophobic cellulose nanopaper via TIPS aligns with green development strategies and could be a promising alternative to petroleum-based packaging materials