In this study, LDPE materials with different kinds of antioxidants were prepared by melt-blending method. To reveal the aging mechanism and the anti-oxidation efficiency of LDPE in the presence of copper, series of characterizations including tensile testing, Fourier transform infrared spectra (FTIR), differential scanning calorimetry (DSC), scanning electronic microscopy (SEM) and computation simulation were performed. The experimental results indicated that the aging process significantly decreased the tensile strength and elongation of those aged samples except 1024, which retarded the aging degradation of LDPE at the same condition. These results were further confirmed by the FTIR analysis with the carbonyl index values. Additionally, the melting peaks of DSC plots became broader and shifted to the lower temperatures during the aging process for S-0, S-3114 and S-1010, whereas no obvious changes were observed for S-1024. Importantly, according to the results obtained from computation simulation, a strong metal-ligand interaction between hydrazide group and copper ions was formed to prevent the further oxidation, which accounted for the excellent anti-oxidation behavior of 1024 for LDPE in the presence of copper. Comparing with general organic polyolefin, polyethylene (PE) has excellent temperature resistance, electrical insulation, dielectric properties and weather resistance due to its long chains with regular CH 2 units. Over the past decades, PE materials have been widely used in various areas, such as medical and health, aerospace, wire and cable, automotive industry, architecture and so on 1-4. Unfortunately, it was found that the chemical structure and composition of PE can be significantly destroyed as a result of the comprehensive factors including crosslinking byproducts, metal impurities, ionic impurities, electrical and mechanical effects, moisture, and chemical substances, which result in the failure of the insulation performance 5,6. For example, it has been reported that thermal aging can lead to the deterioration of electrical and mechanical properties of PE insulation 3,7,8. As discussed above, the introduced metal impurities by the process of manufacturing or the operating can lead to the degradation or even failure of PE insulation 3. The metallic impurities consisting of copper powders, originated from the conductor or the ground water, could form heterocharges, which play a role of enhancing the electric stress and promoting the initiation of water tress, and thus decreasing the strength of the PE insulation. As claimed by Gillen 9 , copper powders could diffuse in ethylene propylene rubber(EPR) insulation matrix during the extrusion process, which can account for the degradation of insulation materials during the thermal aging. The introduction of antioxidant into hydrotalcite can shorten the oxidation induction time, which was indicative of the protective action towards oxidation of polymer, whereas, the impurity of hydrotalcite and metal ions can increase the rate of polypropylene photo...
