Fabrication and mechanical properties of cellulose nanofiber reinforced polyvinyl alcohol composites

Focus on green materials is increasing due to problems associated with environment especially for plastic materials that are non-biodegradable, toxic and containing harmful chemicals. Polyvinyl alcohol (PVA) is a biodegradable, polymer material with excellent mechanical properties, non–toxic and good film-forming ability. Cellulose nanofiber (CNF) is a natural polymer which has a potential as reinforcement material with PVA as CNF showing good mechanical properties, organic and abundant in nature. In this research, the mechanical properties of PVA films, CNF sheets and CNF/PVA composite sheets has been conducted to evaluate the reinforcement effect with different CNF content of 40 wt%, 50 wt%, 60 wt% and 70 wt%. Also, the effect of heat treatment on mechanical properties of the specimens was studied. At increasing CNF content, the tensile strength and Young’s modulus increased up to 217.1% and 109.1% respectively compared to pure PVA films and CNF sheets. Tensile strength and Young’s modulus for heat treated specimens also has shown significant increase up to 75.7% and 13.4% compared to untreated specimens. Increase in CNF content yields higher density CNF/PVA composite sheets. Based on water swelling test, it was observed that as the CNF content increased, the CNF/PVA composite film to be more hydrophobic as less water being absorb. SEM observation showed good compatibility of CNF and PVA resin which contribute to increase in tensile strength of the composite specimens compared to pure PVA film. Increase of CNF content and heat treatment has improved mechanical properties of PVA resin which enables wider range of application