R. V. Gadhave et al.
Many researchers were intrigued by MFC’s capacity to manufacture films be- cause MFC films’ barrier and mechanical properties are comparable with those of existing high-quality polymer matrices [94]. MFC coating and its mixture with petro- and bio-polymer films have attracted the attention of researchers by dramatically improving the barrier properties of the original films [95]. In con- trast to these uses, the use of MFC with cellulosic materials is very new and re- mains uncommon. The first investigation of MFC coating onto paper was con- ducted in 2009 [94]. As ecologically friendly alternatives, many forms of cellu- lose nanofibres derived from cellulosic fibers have been used [96] [97] [98] [99]. Cellulose nanofiber (CNF) has been discovered to improve the properties of various composites and papers when used as a reinforcing element in wet-end applications [96]-[102]. Aulin et al. [103] demonstrated that utilizing CNF as a coating agent significantly reduces the air barrier capability of paper by generat- ing a thick top layer. Hult et al. [101] investigated the mixture of CNF and shel- lac, deposited as a one-layer or multi-layer coating on paper products using a bar coater and a spray coating technique. The results revealed that paper permeabil- ity to water vapor, air, and oxygen decreased dramatically after coating. CNF improved the surface and barrier characteristics of coated sheets, according to Ridgway et al. [104]. The combination of CNF and clay improved the printing properties of paper, such as ink absorption rate and print density, according to Hamada et al. [105]. It was demonstrated that partially replacing NFC for the conventional co-binder carboxymethyl cellulose reduced the permeability of the coating material to water [106]. Andrade et al. studied the impact of several chemicals on the wettability of gelatin-derived edible coatings on banana and eggplant epicarps, discovering that cellulose-nanofibers increased coating wet- ting [107]. 4.5. Lignin Papers made from recycled fibers have poor mechanical and barrier qualities due to insufficient inter-fiber bonding. The coating is a methodology of interest for creating appealing items from this type of paper. On 100% recycled paper, an oxypropylated lignin-based coating was investigated. Instead of propylene oxide, propylene carbonate, a non-volatile and biodegradable solvent, was employed as a reagent. One of them is the creation of lignin-based coatings for paper and pa- perboard applications, which is based on the hydrophobic property of lignin polymer [108] [109]. Some research has previously been conducted on bio-based coatings using cellulose derivatives, starch, and other polymers, [110] as well as a combination of lignin and cellulose nanocrystal or esterified lignin for paper- board use [110] [111] [112]. The subsequent research was of particular interest since they dealt with the esterification of lignin. Another method for lignin modification is oxypropylation, which has been extensively researched to pro- duce novel polyol for polyurethane foam applications [112]. Lehnen et al. [113] investigated oxypropylation with propylene carbonate as a non-volatile and bio- degradable solvent rather than propylene oxide, a possible human carcinogen.
DOI: 10.4236/gsc.2022.122002
15
Green and Sustainable Chemistry
Made with FlippingBook - Online magazine maker