Polyvinyl alcohol based bio-composite films reinforced by liquefaction products and cellulose nanofibrils from coconut coir

In this study, coconut coir was chemically converted to coir-polyols (CP) via atmospheric liquefaction under microwave assistance, during which a combination of polyethylene glycol 400 and glycerol, and 98% sulfuric acid were applied as the liquefaction solvents and catalyst, respectively. The obtained CP was then analyzed in terms of its molecular weight distribution, hydroxyl values, and functional groups. Later, CP/polyvinyl alcohol (PVA) bio-composite films reinforced without and with coir cellulose nanofibrils (CCNF) were prepared. After comprehensive characterization, the CP/PVA films exhibited higher stability in medium-temperature range, while the CCNF/CP/PVA films on the other hand possessed higher properties of tensile strength, elongation at break, and water resistance. The proper dosage of reinforcing agents for preparing PVA-based ternary blend films were proposed at 3% of CCNF and 10% of CP (based on film dry weight), which exhibited the best balance of properties in the critical parameters such as tensile strength and elongation at break.