Effects of Electron Beam Irradiation on Mechanical and Tribological Properties of PEEK

In this work, the mechanical and tribological characteristics of polyetheretherketone (PEEK) sheets were enhanced by electron beam irradiation. PEEK sheets irradiated at a speed of 0.8 m/min with a total dose of 200 kGy achieved the lowest specific wear rate of 4.57 ± 0.69 (10^-6 mm³/N^-1m^-1), compared to unirradiated PEEK with a rate of 13.1 ± 0.42 (10^-6 mm³/N^-1m^-1). Exposure to an electron beam at 9 m/min for 30 runs, with a dose of 10 kGy per run for a total dose of 300 kGy, resulted in the highest improvement in microhardness, reaching 0.222 GPa. This may be due to the decrease in crystallite size, as indicated by the broadening of the diffraction peaks in the irradiated samples. According to the results of thermogravimetric analysis, the degradation temperature of the irradiated samples remained unchanged at 553 ± 0.5 °C, except a sample irradiated at dose 400 kGy, where the degradation temperature shifted towards a lower position of 544 ± 0.5 °C. Differential scanning calorimetry results revealed that the melting temperature (Tm) of the unirradiated PEEK was about 338 ± 0.5 °C, while a high temperature shift of the Tm was observed for the irradiated samples.