Investigating the thermal effects of plasma surface treatment on crystallinity and mechanical behavior of PEEK

This study investigates the influence of plasma surface treatment on the local crystallinity and its impact on the local and global mechanical properties of PEEK samples. Local degree of crystallinity is assessed using Raman spectroscopy, while nanoindentation measurements are employed to examine the nanoscale mechanical properties for commercial, raw injected, annealed, and plasma-treated PEEK samples. The results reveal a significant correlation between the local degree of crystallinity and the nanoscale mechanical properties within the PEEK cross-section. Scanning Electron Microscopy (SEM) observations further support these findings by illustrating the density and evolution of spherulitic structures within the PEEK cross-section. Tensile mechanical tests are conducted to evaluate the influence of crystallinity variation on overall behavior. The results demonstrate that even localized variations in crystallinity can affect the overall mechanical response of PEEK samples. These findings enhance our understanding of the relationship between crystallinity, mechanical properties, and surface treatment on PEEK, providing valuable insights for optimizing its performance in various applications.