Feasibility Study on the Production of Industrial PET Fibers Using Recycled Bottle-Grade PET

PET recycling is one of the most successful examples of polymer recycling. This study explored the mechanical recycling of PET bottles to produce industrial-grade PET fibers. Recycled bottle-grade PET (rPET) underwent solid-state polymerization at 230 °C to increase molecular weight (MW), followed by melt spinning at 300 °C. The weight-average MW reduction rates for virgin PET (vPET) and rPET with the same intrinsic viscosity were nearly identical. However, rPET fibers exhibited lower tensile strength and higher shrinkage rates than vPET fibers at the same draw ratio, primarily due to the presence of IPA units in the rPET structure. Using rPET polymerized to higher MW, the tensile strength of rPET fibers comparable to vPET fibers could be produced. Under UV irradiation, vPET and rPET fibers showed similar trends in tensile strength loss and MW reduction. UV irradiation predominantly affected the amorphous regions of the PET fibers, with minimal impact on the crystalline areas. This study demonstrates the feasibility of producing industrial PET fibers from rPET through SSP and melt spinning, offering a sustainable approach for high-value applications.