Considering the thermal stability of nylon-12 at 230°C, it was projected that the tubes do not undergo thermal degradation during the 5 min of thermal annealing at 170°C. However, DSC measurements of both annealed and untreated nylon-12 tubes show that the samples' crystallinity was modified (Figure ). Despite crystallinity slightly decreasing from 25% to 24%, which should not affect the mechanical properties, the samples exhibited a new endothermic peak at 170°C, suggesting a change in the arrangement of crystalline units.