R. V. Gadhave et al.
much starch in a coating formulation might reduce drying rate [71] [72], reduce picking resistance [73], and maximize cracking area [74] [75]. The ultimate skill is finding a middle ground between quality and price. Starch grafted copolymers can be used instead of starch and synthesized latex. Graft co-polymerization is indeed a flexible method for combining the characteristics of starch and syn- thetic polymers [76] [77]. On the other hand, starch is a biopolymer with a large molecular mass and a high viscosity in an aqueous medium at low concentrations. The starch’s mo- lecular weight must be decreased before it may be adequately grafted in co-poly- merization [78]. Starch-based bio latex is a newly developed water-swollen, a cross-linked starch nanoparticle that commercially replaces synthetic latex [79] [80] [81]. Biolatex is sometimes referred to as starch-based bio-latex, biobased latex, bio binder, and a bio latex binder. Biolatex is a huge step forward in starch-based resins for paper coatings. On an industrial scale, bio latex can try replacing hydrocarbon-based synthesized latex by up to 50% or more [82]. For that reason, biolatex has enormous potential in the manufacturing of coated pa- per. A polymer blend is the physical mixing of two different polymers that may or may not interact chemically [83]. Compared to pure polysaccharide compo- nents, blends of multiple polysaccharides can form a new category of materials with improved mechanical and barrier properties. Starch/PVA mixes have been utilised to improve the characteristics of coated paper. A thin coating of starch/ PVA film was applied to paper. The coated paper demonstrated good organic solvent barrier characteristics. The better barrier properties are due to hydrogen bonding formed by hydroxyl groups of starch and PVA molecules. The hydro- gen bonding on the paper surface form a tight thin layer, which increases the barrier characteristics of starch/PVA films [84]. Ethylene vinyl alcohol and starch mixture Ethylene vinyl alcohol (EVOH) copolymer is a semi-crystalline syn- thetic random copolymer composed of ethylene and vinyl alcohol units [85]. The vinyl alcohol molecule has good air barrier qualities, whilst the ethylene component has great damp resistance, thermal and mechanical properties, and easy handling [86] [87] [88]. Furthermore, EVOH is more biodegradable than normal PVA [89]. Blends of EVOH and hydrophobically altered starch may in- crease the permeability performance of flexible packaging paper. 4.4. Cellulose Nanocelluloses, which have lately been developed, have provided a new polymer coating option. Micro-fibrillated cellulose (MFC) is being used as a coating pulp for paper products. The MFC manufacturing technique was discovered and patented in 1983 by Herrick et al. [90] and Turbak et al. [91]. MFC, a cellulose fiber subdivision, has diameters of 10 - 50 nm and lengths of several microme- ters [92] [93]. MFC had significant reinforcing potential and was employed in nano-composites because of its high aspect ratio, nano-scale dimensions, entan- gled network, and intrinsically good mechanical characteristics [92].
DOI: 10.4236/gsc.2022.122002
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Green and Sustainable Chemistry
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