Structure–Property Relationships of Cyperus papyrus Fibers as Sustainable Reinforcements for Polymeric Composites

The development of sustainable structural materials has driven interest in renewable plant fibers as alternatives to synthetic reinforcements. In this study, the structural, thermal, mechanical, and chemical characteristics of Cyperus papyrus fibers were comprehensively evaluated to assess their potential as reinforcement materials for polymeric composites. The fibers exhibited an average diameter of 164.87 µm, with tensile strength and Young’s modulus values of 141.95 ± 89.33 MPa and 11.15 GPa, respectively. Scanning electron microscopy revealed a rough and irregular surface morphology characteristic of untreated lignocellulosic fibers. X-ray diffraction analysis indicated a crystallinity index of 70.15%, while thermogravimetric analysis demonstrated stability up to 220 °C. Chemical composition analysis revealed high α-cellulose content (63.3%) and moderate lignin levels, contributing to a balance between stiffness and processability. The significant relationship observed between fiber diameter and tensile behavior, together with the structural, chemical, and thermal characteristics of the fibers, provides a broader understanding of the structure–property relationships relevant to their potential use as sustainable reinforcement materials. Overall, C. papyrus fibers represent a promising bio-derived material for environmentally conscious engineering applications.