Extraction of Corn Stalk Macrofibers and Preparation and Performance Analysis of High‐Performance Polylactic Acid Composites

ABSTRACT In stalk fiber/polylactic acid (PLA) composites, the stalk fibers function as the reinforcing filler, and their morphology, chemical composition, microstructure, and spatial orientation directly determine their reinforcing efficiency within the polymer matrix as well as the final performance of the composites. In this study, corn stalk skin was used to extract macrofibers via physical separation, alkaline hydrogen peroxide (AHP), and performic acid (PFA) treatments. High‐performance corn stalk macrofiber/PLA composites were fabricated by ultrasonic‐assisted solution impregnation followed by hot pressing. The effects of different delignification methods on fiber structure, interfacial adhesion, and composite properties were systematically investigated. In addition, cross‐ply (CP), randomly oriented (R), and unidirectionally aligned (UD) fiber architectures were further designed to evaluate the influence of fiber orientation on mechanical performance. The results demonstrate that the PFA treatment effectively removes lignin and hemicellulose while better preserving the cellulose crystalline regions and the macrofiber skeleton, thereby enhancing the interfacial compatibility between the straw fibers and the PLA matrix. Compared with the untreated control sample, the tensile strength and flexural strength of the composite material made from PFA‐treated crop stalk fibers and PLA increased by 60.8% and 82.3%, respectively. Moreover, the CP architecture improved stress transfer and reduced the mechanical anisotropy of continuous stalk fiber composites. This study provides an effective strategy for producing high‐performance fully bio‐based composites from agricultural residues.