Infrared spectroscopy analysis of physico-chemical modifications induced by heavy ions in ultra-high molecular weight polyethylene

Structural analysis with infrared spectroscopy was carried out on ultra-high molecular weight polyethylene (UHMWPE). The polyethylene was irradiated using Li, C, N, S and I heavy ion beams with different fluences. The analysis showed that the absorbance of the CC stretching vibration from trans-vinylene groups containing hydroperoxides presents a maximum at certain ion fluence and is correlated with the ion stopping power. The results were analyzed by a Monte Carlo simulation program that models the irradiation process from a geometrical point of view, in which the latent tracks consist in a central core zone surrounded by a larger perturbed region. This study suggests that it is possible to estimate the core dimension from absorbance measurements as a function of fluence. A possible relationship between this CC structure with the cross-link of two polymeric chains is discussed.