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Cellulose nanofibrils (CNF) were spun into filaments directly from suspension without the aid of solvents. The influence of starting material properties and drying temperature on the properties of filaments produced from three different CNF suspensions was studied. Refiner-produced CNF was ground using a microgrinder at grinding times of 50 and 100 minutes. Filament spinning was performed using a syringe pump-heat gun setting at three drying temperatures of 210 °C, 320 °C and 430 °C. The structure of starting CNF materials was first evaluated using a combination of optical and atomic force microscopy (AFM) techniques. Surface free energy analysis and attenuated total reflectance--Fourier transform infrared spectroscopy (ATR-FTIR) were used to study changes in hydrophobicity due to grinding. Morphology of the filaments was studied using SEM micrographs. The influence of different drying temperatures and grinding times on mechanical properties of the CNF filaments were further investigated through tensile tests and results were compared using statistical analysis. It was observed that drying temperature did not significantly influence the tensile properties of the filaments while cellulose nanofiber suspension type (grinding time) had a significant influence and improved mechanical properties. FTIR results confirmed an increase in crystallinity index and decrease in hydroxyl group availability due to grinding. [ABSTRACT FROM AUTHOR]

• Natural rubber addition to CNF coating improved water vapor barrier and water holdout • Water-based reactions showed evidence of CNF and natural rubber compatibilization • Compatibilization reactions changed suspension rheology and CNF particle sizes • Reactions improved drainage rates during film formation • Crosslinker reactions showed evidence of dispersing natural rubber in coatings Cellulose nanofibrils (CNF) coatings are excellent grease barriers for biodegradable packaging. However, barrier properties are moisture sensitive, so hydrophobic components such as latexes or polymers are needed to impart moisture resistance, but incompatibility leads to poor dispersion. In this work, CNF modified with norbornenes was reacted with natural rubber (NR) latex in water to improve dispersion, coating formation, and coating moisture resistance by creating hybrid particles. Mixtures and reacted samples were coated through filtration onto paper. The hybrid particles improved NR retention and drainage rate as compared to the CNF/latex mixture. Hybrid particle coatings showed more uniform NR dispersion as compared to the mixtures, which formed NR and CNF layers. NR addition to coatings increased the water contact angle, reduced water absorption, and decreased the water vapor transmission rate. All coatings passed a 12-kit grease test before folding and the mixtures formed a crack-resistant CNF layer on the surface. [ABSTRACT FROM AUTHOR]