Ethylene-octene copolymer (EOC) was irradiated using electron beam irradiation at different dosages (30, 60, 90, and 120 kGy). Effect of irradiation dosage on thermal and mechanical properties was studied. When compared to low density polyethylene, EOC exhibited higher degree of crosslinking reflected in increased gel content, higher elastic modulus (G 0 ), and lower tan d obtained by rheology measurement at 150 C. Crosslinking caused improvement in high-temperature creep and room temperature and also elevated temperature elastic properties. Differential scanning calorimetry revealed that e-beam irradiation has caused a gradual reduction in crystallinity and a presence of a fraction with higher melting temperature. In the case of EOC, as the extent of crosslinking increased, stress at break showed an increasing trend whereas irradiation dosage had an inverse effect on elongation at break. Radiation dosage has positive effect on thermal stability estimated by thermogravimetric analysis. After 30 min of thermal degradation at 220 C, slightly higher C¼ ¼O peak for crosslinked sample was found by Fourier transform infrared spectroscopy while for room temperature samples no C¼ ¼O peak was detected.
Ethylene-octene copolymer (EOC) was crosslinked by dicumyl peroxide (DCP) at various temperatures (150-200 C). Six concentrations of DCP in range 0.2-0.7 wt % were investigated. cross-linking was studied by rubber process analyzer (RPA) and by differential scanning calorimetry (DSC). From RPA data analysis real part modulus s', tan d, and reaction rate were investigated as a function of peroxide content and temperature. The highest s' max and the lowest tan d were found for 0.7% of DCP at 150 C. Chain scission was analyzed by slope analysis of conversion ratio, X in times after reaching the maximum. Less susceptible to chain scission are temperatures in range 150-170 C and peroxide levels 0.2-0.5%. Heat of reaction was analyzed by DSC at various heating rates (5-40 C min À1 ). It was found to be exothermic. By projection to zero heating rate, the reaction was found to start at 128 C with the maximum at 168 C.
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