Effect of nitrogen ion irradiation on the nano-tribological and surface mechanical properties of ultra-high molecular weight polyethylene

On the comparison of changes induced in crystallinity and surface nanomechanical properties of ultra high molecular weight polyethylene by γ and swift heavy ion irradiations

“…This result is in good agreement with related literature [2,53,54]. The increase in wear performance observed in UHMWPE after SHI irradiation, reported in [22][23][24]55], can be attributed to a completely different source. Contrary to γ-TT-UH samples, Li-UH and N-UH samples exhibited harder and stiffer surfaces than pristine UHMWPE primarily due to the large increase in degree of crystallinity of the surface layers.…”

“…The optimum fluence appears to decrease with increasing the average (dE/dx) e of the ion beam independently of the ion type [22,26]. In a later work, it was shown that irradiation with N ion, enhances elastic and plastic properties of UHMWPE surface layers, reduces friction and improves nanowear resistance and creep behavior [24].…”

“…The energy and fluence values used in SHI irradiations were selected on the basis of previous studies [10,24,26]. The fluence used for N-UH sample irradiation was the optimal value found for wear improvement [23].…”

“…It is known that some chemical changes appeared in SHI-irradiated polyethylenes if (dE/dx) e exceeds a threshold and the used N ion beam had a larger (dE/dx) e than Li ion beam [9]. In own previous works, the formation of C_C double bonds in a similar N-UH sample was detected by FTIR (ATR mode) analysis [22,24]. FTIR spectra showed the appearance of a band at 965 cm − 1 characteristic of trans-vinylene groups.…”

“…SHI beams can reach up to hundreds of micrometers into polymers and the fluence required to generate structural changes in polymers is within 10 11 to 10 13 ions/cm 2 [6,10,[22][23][24][25]. This technique involves ion beams with energies in the order of MeV.…”