R. V. Gadhave et al.
An oxypropylated lignin-based coating was explored in this work to enhance the general characteristics of recycled paper. Propylene carbonate was employed as an oxypropylation reagent and a solvent in the coating formulation. This enables immediate use of the mixture at the end of the reaction, reducing the number of process stages to one. 4.6. Soya Protein-based biopolymer films have been researched for usage as food wrap- ping and coating materials. They’ve been frequently employed in food systems like oil, gaseous, and mechanical barriers to extending processed foods’ shelf life [112] [113] [114]. Zein was used as an oxygen barrier layer in peanut products to avoid oxidation [115]. Casein coatings might also be utilized on less processed fruits to enhance their shelf life [116]. Trezza and Vergan [117] observed that zeincoated paper does have a high prospective for use as an oil-barrier paper bag in fast-food eateries. Isolated soy protein (ISP) also has a remarkable film-forming capacity [118] [119] [120]. Soy protein sheets have traditionally been used as a digestible covering for veg and meat mixtures that are then fried in oil. ISP- based films beat zein and wheat gluten-based films in terms of oxygen barrier performance [121]. Grease resistance is critical for packing items that include oils or fats. Polyethylene and other polymers are considered effective grease barriers. On the other hand, the polyethylene content makes material segregation, recycling, and regeneration difficult [122] [123]. Papers coated with biodegradable poly- mers may meet packaging criteria as an oil barrier for commodities with a very short lifespan, like as fast-food restaurant sandwiches. ISP, a key by-product of soybean-oil extraction, on the other hand, is a low-cost natural polymer that competes against polyethylene. Mechanical and barrier performance of pro- tein-based coatings are controlled by factors like plasticizer content and pH, solvent, and other additive choices [124]-[130]. As plasticizer content increases in wheat gluten films, flexibility improves while water vapor, oxygen barrier, and puncture strength qualities diminish [125] [126] [127]. Gennadios et al. [119] produced protein films from an ISP-wheat gluten blend. They investigated the impact of varying the pH of the produced film solution on properties such as water vapor permeability and mechanical strength. Brandenburg et al. [120] discovered that alkali-treated ISP films had enhanced film appearance and elon- gation characteristics. ISP films did not seem clear due to the inclusion of in- soluble particles [128]. High pH and temperature treatments of ISP resulted in more soluble, hydrolyzed, and denatured chemicals [129]. Protein denaturation is known to change the structure of a protein from circular to extended chain geometry. Increased protein-protein linkages, in principle, would lower gas permeability while increasing tensile strength. Park et al. [130] revealed that dif- ferent polyethylene glycol and glycerol plasticizer mixtures had a substantial in- fluence on the mechanical properties and water vapor permeabilities of pro-
DOI: 10.4236/gsc.2022.122002
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Green and Sustainable Chemistry
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