ENHANCED THERMAL BEHAVIOR, MECHANICAL PROPERTIES AND UV SHIELDING OF POLYLACTIC ACID (PLA) COMPOSITES REINFORCED WITH NANOCRYSTALLINE CELLULOSE AND FILLED WITH NANOSERICITE

摘要

The objectives of this study were to utilize nanocrystalline cellulose (NCC) and nanosericite (NS) as reinforcing and functional filling agents compounded in a polylactic acid (PLA) substrate for forming novel nanocomposite materials, and subjecting the composites to field-emission electron microscopy (FE-SEM), tensile strength, thermomechanical analyses, thermal gravimetric analysis and UV-Vis spectroscopic analyses; so as to investigate the effect of the modifications achieved by incorporating the nanomaterials on the surface properties, tensile strength, glass transition temperature (T_g), storage modulus, thermal gravimetric loss and shielding efficacy against UV light of different wavelengths. The results indicated that adding suitable quantities of NS and/or NCC to a PLA substrate could improve the overall thermal stability, mechanical strength and UV shielding capacity of the resulting nanocomposites. The shortcoming of weak bonding between NS and PLA could be ameliorated with the addition of NCC. The simultaneous addition of NS and NCC to the composite substrate exerted a greater contribution to the enhancement of the overall functionalities, compared to either bipartite compounds. Based on our results, at a 3% NS and 7% NCC addition rate to the PLA substrate, the most optimal tensile strength was obtained. At temperatures <250 °C, the nanocomposites exhibited good thermal stability and could effectively block about 65% of UVB and UVC irradiation. In the future, the formulations might be applied as a biodegradable UV shielding coating film, or alone, as a medical wrapping material or packaging material.