Central Composite Design of Spraying Process to Laminate the Paper Substrates with Cellulose Nanofibers (CNF) as Green Packaging Wrap.

Green packaging wrap is now required to replace the synthetic plastic coating on the paper substrates. The coating of natural biopolymers on the paper substrates would be a potential method to achieve an ecofriendly coating to replace the synthetic materials which give a threat to the environment. Recently, spraying cellulose nanofiber (CNF) on the paper substrates to boost the barrier and mechanical properties of the paper is a flexible process and potential for scalability. Sprayed cellulose nanofibrils fill the surface pores of the paper substrates and form a barrier film on the paper surface. The spray-coated CNF barrier film on the paper substrates reduced the air passage and increased the mechanical strength. To scale up the process of spraying, the optimization was performed via response surface methodology to investigate the interaction between input variables and their response in spraying process. The variables impacting on the barrier performance, CNF coat weight, and thickness of the coat during spraying are CNF suspension concentration (A), fiber diameter (B), and spray distance from tip to the surface (C). The linear models were developed for CNF coat weight and thickness of the CNF coat weight on the paper substrates. The quadratic model for air permeability was developed with input variables. It concludes that the CNF suspension concentration is a strong parameter for controlling the CNF coat weight and thickness of the CNF coat on the paper substrates. The developed linear and quadratic models were validated with the experimental data confirming that it was a good fit to the real experimental data. From the CCD investigation of spray coating of CNF on the paper substrates, >1 wt.% CNF coating on the paper surface produces good thickness and coat weight on the paper substrates and gives an impermeable CNF laminate on the paper substrates against air. In conclusion, these models could provide a platform for scaling up the spraying process for coating CNF-based nanomaterials on the paper substrates. [ABSTRACT FROM AUTHOR]