The Evolution of Date Palm Fiber-Reinforced Composites: A Roadmap from Conventional Processing to Sustainable Smart Manufacturing

The escalating ecological crisis and low material circularity of modern industry are driving interest in lignocellulosic reinforcements as sustainable alternatives to petroleum-based materials. Date palm fibers (DPFs) are abundant, low-cost agricultural residues with strong potential for waste upcycling, yet their transition into reproducible, high-value composite feedstocks remains limited by variability in fiber attributes and processing constraints. This review critically synthesizes knowledge on short DPF-reinforced composites across thermoplastic and selected thermoset matrices, with emphasis on their transition from conventional manufacturing to material-extrusion additive manufacturing, particularly fused deposition modeling (FDM). Published extraction methods, chemical composition, microstructural characteristics, surface treatments, formulations, and processing routes are examined. To facilitate comparison of reported cellulose, hemicellulose, and lignin contents across different reference bases, a normalization equation is derived and applied. Conventional processing and FDM are comparatively assessed in terms of material formulation, consolidation, porosity, anisotropy, printability, mechanical performance, and sustainability. Although DPFCs can improve stiffness and bio-based content, FDM applications remain constrained by fiber dispersion, melt-flow stability, moisture management, and interlayer defects. Finally, a decision-oriented framework integrating fiber characterization, treatment, compatibilization, filament production, printability, and printed-part evaluation is proposed to support the reproducible and scalable development of sustainable DPF-based composites for advanced manufacturing.