Preparation and Characterization of Cellulose Nanocrystal from Pineapple Leaves for Use in PLA/PBAT Composites

Abstract

This research involves utilizing CNCs technology derived from pineapple leaves to enhance the properties of polylactic acid (PLA) to create a nanocomposite film product with effective UV protection. It also examines the effects on other material properties, such as strength and flexibility, for practical applications of the polymer blend. The experimental process involves extracting nanocrystalline cellulose (CNCs) from pineapple leaves, which are treated through an alkali surface treatment, bleaching to remove lignin, and acid hydrolysis with sulfuric acid to obtain CNCs. The synthesized CNC are then used as a filler in polylactic acid (PLA), which is blended with polybutylene adipate terephthalate (PBAT). The mixture is then formed into nanocomposite films and tested for various properties.
The results showed that PLA/PBAT/CNCs films exhibited a reduction in mechanical properties, such as tensile strength and elongation at break. This reduction is primarily attributed to the agglomeration of CNCs, leading to uneven distribution within the PLA/PBAT matrix, which inhibits effective stress transfer across the material. When the films were tested for UV absorption properties, it was found that the PLA film allowed light to pass through in the wavelength range of 200-224 nm, allowing both UV and visible light to transmit. In contrast, the nanocomposite PLA films exhibited reduced light transmission, indicating that CNCs either absorb or scatter UV light effectively, enhancing UV protection capabilities. Regarding the thermal stability of the PLA and PLA nanocomposite films, adding CNCs to PLA caused the recrystallization temperature (Tcc) to decrease, indicating slower molecular arrangement. At the same time, The melting temperature (Tm) increased when CNCs were added, showing multiple melting behaviors. This phenomenon suggests the presence of different crystalline structures or phases due to the heterogeneous distribution of CNCs within the PLA matrix. The presence of two melting temperature peaks indicates the incompatibility between PLA/PBAT and CNCs.