Microstructure-property relationships in recycled polyethylene terephthalate particle-modified glass/epoxy composites

This is the authors' abstract. We don't add key points for this paper.

Waste polyester textiles require higher-value recycling routes that retain material functionality without energy-intensive chemical processing. Mechanically decomposed waste-PET fragments with a larger S1 particle (median ≈ 209 μm) and a smaller S2 fraction (<100 μm) were incorporated into glass-fabric/epoxy laminates (GF/EP-PET) and particle-filled epoxy composites (EP-PET). Surface coverage, cross-sectional apparent porosity, SEM/EDS morphology, tensile behavior, non-failure bending up to 60°, and Charpy impact strength were evaluated. S2 at 2.5 wt% provided the best overall GF/EP-PET response, increasing tensile strength by 20.0% and 25.5% and elongation at break by 43.1% and 48.9% in the warp and weft directions, respectively; the weft bending stiffness increased by 27.8%. By contrast, S2 at 3.75 wt% increased porosity to 5.799% and reduced tensile strength by approximately 53%. For EP-PET, S1 at 1.25 wt% achieved the highest impact strength of 10.249 mJ/mm 2 , corresponding to a 172.4% increase over particle-free epoxy. The results demonstrate an application-dependent optimum governed by competition between particle-mediated energy dissipation and defect-assisted crack propagation. This method provides a novel, convenient, and environmentally friendly approach for using recycled PET particles as sustainable secondary fillers in customized epoxy based composite materials.