Influence of Accelerated Protons on the Molecular–Topological Structure of Polyethylene

The effect of MeV protons on the surface properties of a low-density polyethylene film was studied using EPR spectroscopy and thermomechanical spectrometry. The diblock semicrystalline structure of polyethylene was preserved upon proton irradiation; the molecular weight decreased, and the weight fraction of the crystalline modification increased. In the EPR spectrum of the irradiated polymer, allyl radicals were predominantly detected. At high proton fluences, the hyperfine structure disappeared from the EPR spectra, and they turned into a singlet with a line width of 4.1 or 3.5 mT as recorded at 23 and –196°C, respectively.