Multiaxial Mechanical and Environmental Characterization of Compression‑Molded Sustainable Polyester Composites Reinforced with Virgin and Recycled Non‑Woven Textiles

Abstract The increasing volume of post-consumer textile and polyethylene terephthalate (PET) waste has intensified interest in utilizing recycled fibers as reinforcements for structural polymer composites; however, the influence of fiber source and non-woven bonding structure on the resulting mechanical, tribological, and moisture-resistance performance remains insufficiently characterized. This study investigates non-woven-reinforced polyester composites fabricated from one virgin polyester preform (P) and three recycled non-woven preforms, two derived from textile waste (R1, R2) and one from recycled PET bottles (R3), varying in binder-fiber content and bonding method (needle punching alone versus combined needle punching and thermal bonding). The precursor fabrics were first characterized for air/water permeability, bursting strength, puncture resistance, and uniaxial strip/grab tensile behavior, after which composite panels of C, CP, CR1, CR2, and CR3 were fabricated via resin impregnation and compression molding and evaluated for bulk density, tensile properties with FE-SEM fracture-surface analysis, dry-sliding tribological wear, and water absorption/thickness swelling with surface morphology analysis. The results showed that composite tensile performance directly inherited the strength ranking of the precursor fabrics CR3 > CP > CR2 > CR1, with CR3 exhibiting the highest maximum tensile load, up to 2488 N, elongation, up to 11.26%, and toughness, up to 22,395 N across all loading directions, correlating with reduced fiber/matrix debonding observed by FE-SEM. Tribological testing revealed that CR2 exhibited the lowest volumetric wear loss across all applied loads ranging from 15 to 35 N, while unreinforced resin exhibited the highest, and CR1 consistently showed the greatest water absorption and thickness-swelling instability over a 10-day immersion period. These findings demonstrate that fiber source and thermal-bonding-derived interfacial integrity, rather than fiber loading fraction, govern the mechanical, tribological, and dimensional behavior of non-woven polyester composites, supporting the viability of recycled PET-bottle-derived non-woven reinforcements as sustainable, high-performance alternatives to virgin polyester fabrics in structural composite applications.