Reactive Modification of Recycled Poly (Ethylene Terephthalate) With Vinyl-Terminated PDMS: Development of Flexible Cushion Filling Fiber

Abstract

The increasing accumulation of post-consumer poly(ethylene terephthalate) (PET) waste has intensified the need for sustainable recycling strategies that produce value-added materials with enhanced performance. In this study, recycled PET (rPET) was reactively modified with 2–10 wt.% vinyl-terminated polydimethylsiloxane (PDMS) through peroxide-induced grafting in the presence of an epoxy-functional chain extender to fabricate flexible silicone-modified fibers for furniture cushion-filling applications. The effects of PDMS incorporation on the chemical structure, morphology, thermal behavior, mechanical performance, resilience, and surface properties of the fibers were systematically investigated using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile testing, compression recovery, cyclic resilience, water contact angle, moisture absorption, and flexibility measurements. FTIR confirmed successful incorporation of PDMS through the appearance of characteristic Si–O–Si and Si–CH₃ absorption bands while preserving the polyester backbone. SEM revealed smooth fiber surfaces and homogeneous cross-sections with stable fiber diameters, indicating improved melt processability and excellent compatibility between PDMS and recycled PET. Thermal analysis showed only minor changes in glass transition and melting temperatures, accompanied by moderate reductions in crystallinity and enhanced thermal stability resulting from the thermally stable siloxane structure. Mechanical characterization demonstrated significant improvements in elongation at break, compression recovery, cyclic resilience, softness, and hydrophobicity, while maintaining adequate tensile strength for cushioning applications. The water contact angle increased from 73.2° for unmodified rPET to 126.4° for the 10 wt.% PDMS-modified fibers, whereas moisture absorption decreased by more than 70%, indicating markedly improved water resistance. Among the investigated compositions, 6–8 wt.% PDMS provided the optimum balance between mechanical integrity, flexibility, resilience, thermal stability, and surface hydrophobicity. These findings demonstrate that reactive silicone modification is an effective strategy for upgrading post-consumer PET waste into high-performance, resilient fibers suitable for sustainable furniture cushion-filling applications and other value-added textile products.