Effect of Thermal Treatment on Morphology and Structural Stability of Polyamide 6 (PA6) Nanofibrous Membranes

This study examines the impact of high-temperature thermal treatment on the structural and thermal stability of polyamide 6 (PA6) nanofibrous membranes. Dimensional and thermal stability are crucial for their application in filtration, nanosensors, and biomedical devices. The primary aim was to assess the effect of thermal treatment on the dimensional stability of PA6 membranes and to identify optimal conditions for minimizing shrinkage. Two heat-treatment techniques, hot air oven (isotonic) and hot press (isometric), were applied at 150–200°C to examine their effects on shrinkage and fiber structure. The treated membranes were further soaked in boiling water to assess their dimensional stability. The morphology, microstructure, and thermal degradation of the PA6 nanofiber membranes were characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Differential Scanning Calorimetry (DSC). Results showed that hot air treatment caused significant shrinkage, increasing from 10.7% at 150°C to 39.3% at 200°C, whereas hot pressing resulted in significantly lower shrinkage, from 8.7% to 6.7% over the same temperature range, and decreased further to 4.6% under optimal conditions (180°C, 5 minutes). FTIR confirmed the chemical stability of PA6 after thermal treatment, and SEM revealed improved fiber packing with reduced deformation in the hot-pressed samples.