Chemical and Mechanical Stability of Rotary-Die-Extruded Recycled PET Fibers Under Aggressive Aqueous Environments

This study evaluated the chemical and mechanical stability of recycled polyethylene terephthalate (rPET) fibers produced by rotary die extrusion under selected aqueous exposure conditions. The rPET fibers, natural wool, cotton batting, and a polyester and cotton apparel fabric were exposed to powder detergent, liquid soap, bleach, and dilute hydrochloric acid for periods ranging from 2 h to 7 days. Mass retention was assessed for all materials, whereas tensile properties were evaluated only for rPET. The rPET fibers retained between 99.92 and 100% of their initial mass and more than 95% of their initial tensile strength after 7 days of exposure. Wool showed its greatest mass loss in bleach, while cotton batting and apparel fabric showed measurable mass losses under specific exposure conditions. These reference materials differed in composition and physical form and were therefore used only to provide descriptive context. Overall, the results indicate high mass retention and tensile property retention of the investigated rPET fibers under static exposure at 25 °C. The findings support their potential use in textile applications requiring resistance to the tested aqueous environments but do not establish molecular chain integrity or equivalence with virgin PET.