Structural, rheological, and mechanical properties of polyvinyl alcohol composites reinforced with cellulose nanofiber treated by ultrahigh-pressure homogenizer

Cellulose nanofibers (CNF) were prepared by nanoisolation using a newly developed ultrahigh-pressure homogenizer (UHPH). The CNF was treated by UHPH with 0, 10, and 20 passes. The effect of UHPH on defibrillation of the CNF and its structure was investigated. The UHPH-treated CNF reinforced poly(vinyl alcohol) (PVA) composite was fabricated by solvent casting. The effect of CNF on morphology, high-order structure, rheological property, and mechanical performance of PVA/CNF composites was investigated. Structural analyses revealed that fiber diameters and fiber distributions of the CNF decreased, and the relative crystallinity increased with an increase in the UHPH passes. The mechanical treatment by UHPH promoted CNF fiber dissociation without interfering with the CNF crystal structure. High crystallinity and interaction of the hydrogen bonding of the defibrillated, treated CNF significantly enhanced the mechanical performance of the PVA/CNF composites. The UHPH treatment presented defibrillated CNF with high crystallinity, which was developed for the high-potential cellulose nanofiber in fiber-reinforced composite materials.