The contribution of silica nanoparticles to the stability of styrene-isoprene-styrene triblock copolymer (SIS). II. Energetic peculiarities

This study presents the stabilization activity of silica nanoparticles added in the matrix of styrene-isoprene -styrene triblock copolymer (SIS). The isothermal chemiluminescence develops the capacity of filler to delay oxidative degradation in gamma-irradiated probes. The kinetic parameters, temporal values and activation energies characterize the efficient protection offered by n-SiO2 particles. The increase in the silica content (2, 5 and 10 wt %) provides a significant stability improvement. Even the strength analysis applied to modified polymer samples indicate a slight extension of degradation period, the values of their activation energies are conclusively high according with the protection effects of filler. The association of this additive (5 wt %) with rosemary extract powder (0.5 wt%) reveals a valuable couple of antioxidant compounds, whose high synergistic effect is depicted by great co-operation factors. The results of kinetic investigation on oxidation inhibition over a large dose range, up to 100 kGy may be usefully extended to other polymers and the results are appropriate for the application of radiation sterilization and radiation technologies for the improvement of product life times or the recycling of polymer wastes into ecological materials.