Effects of high dose gamma irradiation on the properties of green low density linear polyethylene (GREEN PELBD) used in electrical cable coatings

The use of renewable raw materials, as a sustainable alternative for the production of conventional plastic, showed great economic-environmental potential. In this segment, green polyethylene (green PE) is excellent, which is produced from ethanol from Brazilian sugar cane. The Linear Low Density Polyethylene (PELBD) is used in industrial films, tarpaulins, toys, healthcare and medicine products, as well in electrical cable coatings. Accelerated degradation of such cables and coatings due to continuous exposure to ionizing radiation is a serious problem in nuclear power plants, especially in cables that power security systems. Thus, it is important investigations of the interaction of gamma radiation with the polymeric compound containing green PELBD, a polymer system with potential use for electric cable coating in nuclear power plants. In the present work, ethylene-polymerized PELBD obtained from the dehydration of ethanol from sugarcane is called green PELBD (linear low density polyethylene).The goal of this work is to use the thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and mechanical tensile tests techniques to evaluate the effects of high doses of gamma irradiation on electric cable coatings whose composition contains linear low density polyethylene (LLDPE), made with green polyethylene technology, which uses sugarcane as raw material to obtain the ethylene monomer. The samples, pieces of electrical low voltage cable coatings (<1kV), were irradiated at doses of 15, 30, 60, 150, 250; 500 and 1000 kGy. Thermogravimetric analysis (TGA) showed that oxygen markedly influences the thermal degradation profile of the polymer, while the effects of gamma irradiation on the LLDPE macromolecule structure are notorious by the FTIR analysis. Mechanical tensile tests showed that gamma irradiation at high doses degrades the mechanical properties of green LLDPE. On the other hand, it was observed that the electrical cables coated with this polymer composite have sufficient lifetime to be used during the complete cycle of nuclear power plant (NPP) operations (~ 40 years). The results will contribute to future researches on gamma irradiation in Green Polyethylene and also on the use of green polymers in Nuclear Power Plants. Both themes, although still little discussed in academic fields, have relevant economic and environmental importance. (author)