Polycarbonate is an engineering polymer due its outstanding properties and is widely used in several different applications. In some of these applications it can be exposed to certain liquids/solvents. In many cases, this liquid exposure may cause an effect known as Environmental Stress Cracking (ESC), which may lead to crack formation on the polymer surface and consequent reduction of its mechanical resistance, with loss of lifetime. On the other hand, polycarbonate medical supplies are often exposed to gamma rays in the radio-sterilization process, at doses up to 25 kGy. This exposure causes main chain scissions. In this present work, the viscosity average molecular weight decreased about 10% at 25 kGy. Elongation at break was drastically affected by ESC phenomenon. When simultaneously exposed to the ESC agents (methanol or isopropanol) and gamma radiation, combined effects of both takes place. Moreover, the stress relaxation rate of ~1000 Pa/s (air or methanol) and ~2200 Pa/s (isopropanol) at the dose of 100 kGy, suggests strong influence of isopropanol as surfactant on PC. Results of elongation at break and stress relaxation rate were reliable data to evaluate ESC and radiolytic effects on PC.

Bio-based linear low-density polyethylene (green LLDPE) composites are used as electrical jackets/insulator for cables. Assessments of gamma-irradiation (Co-60) effects on these materials are of interest as they might be used in nuclear power plants (NPPs). Brazilian sugarcane juice-based green LLDPE composite electrical jackets were irradiated until 1000 kGy and analyzed for thermal stability and mechanical characteristics. Thermogravimetry analysis (TGA) showed increasing of pyrolysis activation energy (Ea) (under N2) from 42.7 ± 4.2 kJ/mol in unirradiated samples to 72.8 ± 4.6 kJ/mol after 60 kGy dose, as resulted of radiation-induced effects. FTIR spectra evidenced radiation-induced formation of conjugated C=C bonds after 250 kGy dose. Tensile stress and Young modulus did not change significantly until 150 kGy dose, whereas elongation at break decreased and reached 50% at 91 kGy dose. These results suggest that green LLDPE might withstand radiation damage through a NPP operating life (~ 40 years).