Tensile, thermal and ultra-violet shielding enhancement of poly(lactic acid) bionanocomposite film using cellulose nanocrystals extracted from sugarcane bagasse

Sugarcane bagasse fiber cellulose nanocrystals (SBFCNC) and microcrystalline cellulose-derived-cellulose nanocrystals (MCC-CNC) were extracted from sugarcane bagasse fiber (SBF; an agricultural waste) and microcrystalline cellulose (MCC), respectively. Both SBFCNC and MCC-CNC were synthesized using sulfuric acid hydrolysis followed by the freeze-drying method. Both MCC-CNC and SBFCNC show stable suspension in water with zeta potential values of - 40.5 mV and - 42.2 mV, respectively. Transmission electron microscopy (TEM) analysis revealed that the SBFCNC has a higher aspect ratio (l/d = 65) compared to the MCC-CNC (l/d = 25). The poly(lactic acid) (PLA) nanocomposites containing of MCC-CNC and SBFCNC was prepared using solvent casting method, and the films are highly amorphous as evidenced from the differential scanning calorimetry (DSC) study. The tensile strength of PLA/SBFCNC-10 is higher than that of PLA/MCC-CNC-10 films. Thermogravimetric analysis (TGA) results showed that the thermal stability of PLA was improved significantly by the incorporation of MCC-CNC and SBFCNC. Poly(lactic acid)/SBFCNC-15 nanocomposites exhibited higher UV shielding properties (i.e., a UV blocking ratio of 0.63-0.66 in the UVA, UVB, and UVC regions) compared to PLA/MCC-CNC-15 nanocomposites (a UV blocking ratio in the range of 0.38-0.54). Sugarcane bagasse fiber cellulose nanocrystal is a potential biofiller that can provide good thermal stability and UV shielding properties for green bionanocomposites, which can give it an opportunity for food packaging applications.