Effect of Bremsstrahlung Radiation from Accelerated Electrons on the Structure and Surface Morphology of Low-Density Polyethylene

A comprehensive study of the structural and morphological changes in low-density polyethylene induced by bremsstrahlung irradiation in the dose range of 0–900 kGy is presented. The observed effects are compared with those resulting from Co-60 gamma irradiation. The novelty of this work lies in the identification of specific features of structural modifications occurring in the near-surface layer of low-density polyethylene under bremsstrahlung irradiation with a continuous energy spectrum (with a maximum energy up to 4.5 MeV), applied for polymer modification. It is shown that at a dose of 100 kGy, the degree of crystallinity increases from 39.5±1.5% to 41.3±1.4%, indicating the predominance of radiation-induced structural ordering processes. With a further increase in dose up to 900 kGy, the crystallinity decreases to 32.4±1.7%. At the same time, new bands appear in the Raman spectra at ~1672 and ~1720 cm -1 , corresponding to the formation of carbon–carbon double bonds and carbonyl groups, which indicates the dominance of degradation and oxidative processes. The study of surface microrelief reveals smoothing effects at high doses. The average surface roughness (Ra) changes from 27.9±1.2 nm to 37.8±2.1 nm (~400 kGy), followed by a decrease to 30.2±1.5 nm (~900 kGy). Comparison with gamma irradiation results demonstrates the specific nature of bremsstrahlung effects, associated with its continuous energy spectrum and the near-surface character of energy absorption, leading to the formation of inhomogeneous structural modifications in the surface layer.