Toward transparent rigid packaging from sugarcane bagasse: a consistency-testing framework for nanocellulose-chitosan sheets

Abstract

A theoretical and computational study. No experiments were performed; every parameter is taken from a verified literature source or stated as an assumption, and every output is a screening estimate rather than a prediction of material behaviour. Prepared for submission to Cellulose (Springer). Transparent rigid packaging is dominated by fossil-derived polymers, while fibre-based packaging is opaque. Dense cellulose nanofibril and nanocrystal sheets are transparent as flat films, but whether transparency, wet stiffness and a three-dimensional shape can coexist in one sugarcane-bagasse-derived package has not been established. The only reported attempt to mould transparent CNF objects failed because of drying shrinkage. Three consistency screens are applied to a proposed bagasse CNF-chitosan-wax architecture: an optical screen derived from Debye-Bueche scattering theory, a wet-stiffness screen for CNF-chitosan sheets, and a geometric forming screen. Each is propagated through a seeded Monte Carlo analysis (200,000 samples). Optical. Bulk haze scales with wall thickness and with the cube of the correlation length of the void structure. The scattering prefactor is derived (64 pi^4/3), not fitted. A 100 um wall at 10% haze and 5% void fraction requires a correlation length of about 10 nm or less, and the closed-form cubic law overestimates scattering by 7x at 80 nm, the top of the reported bagasse nanofibril range. Wet stiffness. Chitosan raises modelled wet stiffness only through cross-linking, and the benefit disappears in an acidic liquid. Forming. Geometry sets the burden: tray, bowl and cup shapes require total strain tolerances of 0.26, 0.67 and 1.10, and no combination of the assumed ranges forms the cup (best case 0.96). The deposit contains the manuscript, the Supplementary Information and, in the software record, the complete model, the verification suite, every figure script, the reference-verification tooling and a log of the literature searches behind each statement of absence.