Prediction of long-term creep response: accelerated characterization of industrial nylon6,6 and HMLS PET filaments

Abstract

The performance of polymeric materials in dynamic loading conditions and their long-term reliability are the two main issues practitioners in the composite field face today. The purpose of this study was to construct master creep curves for industrial nylon6,6 and high modulus-low shrinkage polyethylene terephthalate (HMLS PET) filaments in order to predict their long-term performance. Here, the procedure to develop the master creep curves with short-term creep strain of industrial filaments was investigated under different isothermal conditions in the glass transition region. Nylon consistently exhibits a higher short-term creep strain than PET by around 5–10% based on its lower tensile modulus. Then, master creep curves were developed to foresee the creep of yarns for almost two decades (∼20 years) by the Time-Temperature Superposition principle shift factors. Based on the shift factors derived from master curves, PET and nylon have constant activation energies over the temperature range tested, implying that their creep mechanisms remain constant regardless of the temperature. Overall, rapid prediction of filament creep behavior and lifetime using this method is proposed.