Executive Summary : | This proposal aims at developing coating materials for paper using bio-based renewable raw materials by suitable chemical functionalization. The chemical functionalization is targeted towards improving the properties of kraft papers so that they can be used as potential packaging material. The kraft papers are made of ligno-cellulosic biomass that are non-toxic and bio-degradable. They are often being used as shopping bags, food wrappers etc. as an alternative to plastic-based packaging. Kraft papers have good strength, but they lack in many properties that renders their wide use by replacing plastic-based packaging. The main disadvantage of kraft papers is the poor water and oil resistance. They readily absorb water and lose the strength. In a similar way, they have very poor moisture barrier property that should be high for food packaging application. In order to resolve those problems, the kraft papers are generally coated or laminated by synthetic non-degradable polymers like styrene-butadiene latex and low-density polyethylene. Now-a-days, all the kraft paper-based packaging comes with a coating of such synthetic polymers that provide good water repellency and moisture barrier property. However, that is not a sustainable solution because the non-degradable part affects the bio-degradation of package after end use and creates plastic pollution. There is an immense need to develop a plastic-free coating for kraft paper that will provide the desired properties along with biodegradability. In order to develop such coating, this proposal delineates the formulation of coating for kraft paper using fully bio-based materials like Chitosan and micro-crystalline cellulose that are non-toxic and bio-degradable. Those materials have very good research importance because of their numerous functionality (‒NH2 and ‒OH) and ease of functionalization. Utilizing that opportunity, this proposal describes suitable functionalization using triacrylate, long-chain alkyl amine, and polydimethysiloxane (PDMS) by Michael addition reaction at ambient condition. Due to the excellent aqueous dispersibility of Chitosan and cellulose crystals, the functionalization reactions will be performed in water and therefore the ultimate coating material will be obtained as aqueous dispersion. It will allow the opportunity to make a coating on kraft papers by simple dip-coating process followed by the evaporation of water. The curing of triacrylate will cross-link the Chitosan molecules and thereby mechanical reinforcement of kraft paper will be achieved. The functionalization by long alkyl chain will provide water repellency to the coating and PDMS will provide the resistance to both oil and water. Although PDMS is non-toxic and bio-compatible, its content will be optimized to a minimum because of its non-biodegradability. Here, the Chitosan will provide anti-microbial property to the coating whereas the cellulose crystals will offer the gas or moisture barrier properties. |