Assessment of Mechanical Degradation in Polyester Fibers for Offshore Mooring through Hydrolysis Processes in Seawater

For decades, polyethylene terephthalate (PET) has been a prominent material for high-performance polymer fibers, finding widespread applications in offshore mooring. PET offers cost-effectiveness, high strength, ease of processing, compatibility with other fibers, and recyclability. This article presents the depolymerization of PET for material aging via hydrolysis conducted with seawater (South Atlantic) at three different elevated temperatures, with hydrolysis time of up to 100 days. Three PET fibers with different linear densities are used, and the experimental investigation involves measuring the breaking strength through yarn break load (YBL) tests to evaluate the effect of hydrolysis conditions (time, temperature) on the mechanical behavior of the multifilaments. A constant reduction in strength is observed for all PETs due to hydrolysis time. However, within the studied temperature range, the maximum strength loss is not always associated with the highest temperature. Additionally, several models are used to fit the effects of hydrolysis exposure time and temperature on yarn strength, providing both 2D and 3D models that describe the phenomenon.