Analyzing Temperature Dependent Shrinkage Stress Evolution in High Speed Spun, High Molecular Weight Poly(ethylene Terephthalate) Filaments

The effects of fiber structure on temperature-dependent shrinkage stress evolution in high speed spun, high molecular weight poly(ethylene terephthalate) (PET) filaments are investigated. Based on the hypothesis that thermal stress evolution with temperature is a relaxation spectrum of a series of oriented structural elements, a measured shrinkage stress/temperature curve is fitted using a model that is the sum of three component peaks. The model, composed of three Pearson-Pisa functions, describes the experimental curves very well. Variations in fiber structure such as amorphous orientation and crystalline development are reflected signally in changes in the calculated curve parameters of component peaks. The curve resolution analysis reveals the contribution of each kind of ordered region to the entire shrinkage stress evolution in high speed spun, high molecular weight PET filaments and its variation with fiber structure.