Eco‐friendly enhancement of poly(lactic acid)/poly(butylene adipate‐co‐terephthalate) bridgeable composites using natural cotton stalk: A novel approach to improved mechanical, barrier properties, and compatibility

Abstract This study investigates the potential of using natural cotton stalk (CS) to enhance the properties of poly(lactic acid) (PLA) and poly(butylene adipate‐co‐terephthalate) (PBAT) composite materials. Simple processed CS, used as a bio‐based filler, is integrated into the PLA/PBAT matrix with the objective of improving mechanical properties, barrier performance, and compatibility, while simultaneously reducing costs and environmental impact. The experiments conducted include tensile testing, scanning electron microscopy analysis, Fourier‐transform infrared spectroscopy (FTIR) analysis, X‐ray diffraction study, thermogravimetric analysis, contact angle measurement, water absorption tests, as well as water vapor and oxygen permeability tests. The results demonstrate that the inclusion of CS significantly enhances the mechanical properties and crystallinity of PLA/PBAT composites, along with increasing their water vapor and oxygen barrier capabilities. Compared to PLA/PBAT without CS, the addition of 2% CS to PLA/PBAT led to substantial improvements in tensile strength and elongation at break, with increases of 21.5%, 41.6%, and 74.4%, respectively. Additionally, scanning electron microscopy and Fourier‐transform infrared spectroscopy analyses indicate that the incorporation of CS promotes the compatibility and chemical interaction between PLA and PBAT, thereby enhancing various properties of the composite material. Image analysis revealed that the distribution area of CS fibers in the polymer matrix increased with content up to a peak at 2% but decreased at higher contents due to severe agglomeration, leading to uneven distribution and performance decline. This work proposes three possible reasons for the improvement in water vapor and oxygen permeability performance. Overall, the analysis suggests that an optimal amount of CS can effectively enhance multiple properties of PLA/PBAT composites, while excessive CS may lead to a decline in performance. Highlights Cotton stalk (CS) boosts polylactic acid/poly(butylene adipate‐co‐terephthalate) (PLA/PBAT) tensile strength by 21.5% and elongation by 41.6% at 2% inclusion. CS addition enhances water vapor and oxygen barrier properties of PLA/PBAT. Scanning electron microscopy and Fourier‐transform infrared spectroscopy show CS improves PLA/PBAT compatibility and strength. Optimal CS content at 2% identified for best mechanical and barrier performance. Study validates using agricultural waste as fillers in eco‐friendly composites.