فهرست نشریات علمی دسترسی آزاد ایران

The recycling of polyethylene terephthalate (PET) has become increasingly important due to environmental concerns and the growing demand for polyester fibers. However, multiple recycling cycles result in chain scission, reduced intrinsic viscosity, and deterioration of rheological and mechanical properties, limiting the reuse of recycled PET (rrPET) in high‑performance applications. This study investigates a dual modification strategy combining reactive rheology with nanocomposite flame-retardant engineering to restore rrPET to fiber-grade quality. Epoxy-based chain extender Joncryl ADR4468 was employed to reconnect fragmented chains, increase molecular weight, and enhance melt elasticity. Rheological characterization confirmed significant improvements in complex viscosity, yield stress, and viscoelastic stability, enabling stable fiber spinning. To address flammability, halogen-free zinc phosphinate (ZPi) and Cloisite 30B nanoclay were incorporated. The synergistic action of phosphorus-based flame retardant and layered silicate nanofillers improved thermal stability, enhanced shear-thinning behavior, and promoted uniform dispersion within the polymer matrix. Morphological analysis revealed homogeneous fiber structures with reduced agglomeration, while flame‑retardant testing demonstrated elevated limiting oxygen index (LOI) values and compliance with UL94 standards .