Drying-Induced Microstructural Control of Montmorillonite Clay-Cellulose Nanofibril Films and Its Effects on Thermal Degradation and Flammability
ORCID
Pokhrel: https://orcid.org/0000-0002-0919-4193; Kim: https://orcid.org/0000-0002-5330-1670
MSU Affiliation
College of Forest Resources; Department of Sustainable Bioproducts
Creation Date
2026-10-02
Abstract
The growing use of polymeric and bio-based materials has driven a demand for the development of flame retardants (FRs) that are effective, durable, and environmentally benign. Montmorillonite clay-cellulose nanofibril (MC-CNF) composite films have emerged as promising nacre-inspired, bio-based FR systems because of their brick-and-mortar architecture and inherent barrier-forming capability. However, how drying-induced microstructural evolution influences their thermal degradation and FR performance has yet to be fully explored. In this study, we report the impact of drying kinetics on the microstructural organization, thermal degradation behavior, and flammability response of MC-CNF films. Composite films were fabricated via aqueous solution processing followed by either vacuum-assisted or ambient drying to systematically alter MC platelet packing and interlayer orientation. Scanning electron microscopy revealed layered, nacre-like architectures with MC platelets embedded within the CNF matrix. X-ray diffraction confirmed that ambient drying facilitated the formation of a brick-and-mortar microstructure in MC-CNF films compared to vacuum drying, particularly at the MC loading up to 20% where the size of MC crystallites was 78% larger. Thermogravimetric analysis showed that ambiently dried films exhibited an earlier onset of thermal degradation and produced a higher char yield compared to vacuum dried counterparts. Vertical flammability testing showed significant charring behavior and flame resistance of the composite films at MC loadings as low as 20%. These results establish a direct processing-structure-degradation relationship in MC-CNF films and highlight drying-induced microstructural control as a critical design parameter for the development of sustainable, bio-based FR materials.
Keywords
cellulose nanofibrils, montmorillonite clay, nacre-inspired biocomposites, flame retardants
Publication Date
8-19-2026
Publication Title
Materials Chemistry and Physics
Publisher
Elsevier
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License
Rights
© 2026 The Author(s).
Recommended Citation
Sedhain, G., Kaya, G. B., Pokhrel, D., & Kim, Y. (2026). Drying-induced microstructural control of montmorillonite clay-cellulose nanofibril films and its effects on thermal degradation and flammability. Materials Chemistry and Physics, 368, 133007. https://doi.org/10.1016/j.matchemphys.2026.133007
