The Effects of UV Irradiation to Polyetheretherketone Fibres

The effects of UV irradiation on polyetheretherketone (PEEK) fibers were investigated in this study. PEEK fibers were manufactured with a melt spinning system and then artificially aged with simulated solar UV light. Fibers were then characterized with mechanical tests, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), rheology, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). PEEK, best known for its excellent thermal stability, suffered greatly due to the effects of UV irradiation. The low UV stability could be observed as embrittlement of the fibers in the mechanical tests, increased crosslinking rate in the rheological tests, formation of carbonyl and hydroxyl groups and changes in the carbonhydrogen bond nature in the FTIR, worsened thermal properties in the TGA and transverse cracks in the SEM photos. DSC was found to be an inaccurate technique in estimating the degradation level of PEEK fibers whereas the carbonyl index measured by FTIR was found to be the most convenient technique.