Properties enhancement of chitosan‐filled polylactic acid biocomposites using tannic acid treatment

In this study, tannic acid‐treated chitosan (Cs‐TA)‐filled polylactic acid (PLA) biocomposites were fabricated through the melt blending and compression molding methods. The effects of Cs‐TA and their loadings (2.5, 5, 7.5, and 10) php on chemical interaction, tensile, melt processing, thermal, water absorption, and morphological characteristics were analyzed accordingly, and compared with a previously untreated PLA/Cs biocomposite. Fourier transform infrared spectroscopy analysis revealed that TA could form a cross‐linked network with Cs components as well as improving the hydrophilicity character of Cs for better interaction with PLA polymer. In addition, tensile strength and elongation at break were enhanced to the extent of ~3% and ~11%, respectively, at optimal 3% w/v TA concentration and 2.5 php Cs loading. Melt processing analysis of treated PLA/Cs‐TA demonstrated a lower stabilization torque, which implied improvement in the PLA processability. Moreover, chemical modification of Cs with TA showed a positive effect on thermal stability correlated to a higher decomposition temperature. Meanwhile, the crystallinity degree was considerably increased with TA treatment ascribed to the acceleration in crystallization process. Besides, a lower water uptake percentage proposed the Cs‐TA potential in controlling water uptake in PLA/Cs biocomposite. Indeed, the morphological analysis exhibited better filler dispersion and interfacial adhesion between Cs‐TA and PLA polymer, which justified the enhancement in all studied properties.