Comparison of NaOH-Based Solvents for Lignocellulosic Microfines (LCMFs) Dissolution and Properties of Regenerated Cellulose Film

Cellulose dissolution solvents have been developed for the fabrication of regenerated cellulose (RC) films, which are known for their high optical transparency, excellent barrier properties, and biodegradability. In this study, three types of aqueous dissolution systems, including glycol ether/sodium hydroxide (NaOH), poly(ethylene glycol) (PEG)/NaOH, and urea/NaOH aqueous systems, were investigated to compare their effects on lignocellulosic microfine (LCMF) solutions and the resulting regenerated cellulose films. The dissolution yields of LCMFs in these solvents ranged from 77.0% to 85.0%. The incorporation of glycol-based co-solvents in NaOH significantly influenced the transparency (over 70% of transparency) of the regenerated LCMF films. The use of a high molecular weight of co-solvent (PEG) especially resulted in enhanced stability of the LCMF solutions, as evidenced by higher inherent viscosities and the minimal viscosity change over 30 days compared to glycol ether/NaOH and urea/NaOH systems. Furthermore, the films regenerated from the PEG/NaOH solvent showed the lowest shrinkage (19.4%) and the highest mechanical strength (47.8 MPa), followed by the glycol ether/NaOH and urea/NaOH systems. These results confirm that the type of co-solvent in cellulose dissolution systems influences the composition, coagulation behavior, and drying characteristics of regenerated LCMF films, affecting their mechanical performance. This study provides insights into the effective utilization of lignocellulosic materials for the efficient fabrication of regenerated cellulose.