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polymers. Many chemical strategies have been discovered to increase PVA’s wa- ter resistance. The water-resistance of PVA has been enhanced via grafting of acrylonitrile monomer with PVA. Some studies developed PVA/polyacrylic acid mixtures to reduce PVA’s hydrophilic characteristic [42]-[52]. A cross-linked esterification process occurred between polyacrylic acid and PVA molecules. PVA molecules’ hydrophilic hydroxyl groups were transformed into hydropho- bic groups. As a result, the water resistance of the PVA film was substantially enhanced. Biodegradable materials have gained popularity as a result of envi- ronmental concerns. One of the merits of IA is renewability. Furthermore, it has the potential to reduce people’s dependency on petrochemical products such as acrylic acid and maleic anhydride when picking raw materials for polymer syn- thesis [53]-[58]. This study used free radical polymerization to produce a PVA/ IA/AM copolymer having excellent water resistance and durability. PVA’s hy- droxyl groups can create ester bonds with IA molecules’ carboxyl groups. It can increase the hydrophobicity of PVA. The double bond of itaconic acid may po- lymerize with an acrylamide monomer to form a structural matrix. Thereby, this could restrict PVA diffusion into the interior of the paper. Mini-table software was used to design the PVA/IA/AM copolymer experiment. It sought to enhance PVA’s hydrophobicity, increase surface strength, and decrease PVA penetration. PVA/IA/AM can establish additional hydrogen bonding with fibers and has bet- ter film-forming characteristics over PVA [59] [60]. 4.3. Starch Starch and its compounds have indeed been largely used in the paper industry because of its complete biodegradability, abundant availability, and relatively inexpensive. Surface coating of starch-derived goods is a well-established com- mercialized procedure for acquainting paper with desirable qualities. As a raw material, starch is exceptionally versatile. First, starch is a natural polymer with a large molecular mass that can be precisely depolymerized. It is also a hydrophilic polymer, meaning it dissolves in water and creates hydrogen bonds with cellu- lose fibers and pigment. Third, starch contains hydroxyl groups, which allow for a variety of substitution or oxidation methods to change its rheological charac- teristics and prevent retrogradation. Starch graft co-polymerization can generate innovative materials that combine the advantages of natural and synthesized polymers [32] [61]-[68]. Coated paper is a form of paper that consists of a base coat and a top layer. The coat color is applied to the base paper during the coat- ing process to improve its qualities. Coat color is primarily made up of binders, pigments, and other additives. Binders are the second most common coating component after pigments [69]. Natural binders including starch and protein or synthesized latex such as styrene-butadiene, poly (vinyl acetate), and poly-acrylates are employed. When compared to synthetic latex, starch is a relatively low- priced binder. However, nature-derived starch applications are restricted be- cause of its insolubility in cold water, tendency to retrograde, and decrease in viscosity and thickening power during cooking and storage [70]. However, too
DOI: 10.4236/gsc.2022.122002
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Green and Sustainable Chemistry
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