Accelerated Degradation of Polypropylene Mitigated by Cooperative Effect of n-SiO2 and Rosemary Extract

Abstract

This study analyzes the stabilization effects of silica nanoparticles and rosemary extract on polypropylene during accelerated degradation caused by exposure to γ-rays. The accurate procedures involved in the mitigation of oxidative degradation (isothermal and nonisothermal chemiluminescence) allow for the identification of the appropriate filler concentration and cooperative effect with rosemary extract, which significantly improves PP durability. The examination of the stability attained by PP modification reveals strictly differentiated values of activation energies: 100 kJ mol−1 to 145 kJ mol−1 required for nonirradiated PP as pristine material and highly modified compounds by the couple, respectively, and 79 kJ mol−1 to 143 kJ mol−1 required by the samples after receiving 50 kGy. This indicates the efficient protection identified in this investigation for PP against oxidative degradation during operation under very harsh energetic conditions. The contribution of the studied additives is illustrated by the several-fold improvement of the kinetic parameters, such as the oxidation induction time, that describe material protection. This feature may be appropriately extended to the valorization of PP waste for recycling. While silica nanoparticles act as an efficient scavenger by the trapping of radicals in the superficial lattice defects, rosemary extract provides the protective role of its polyphenol components through the replacement of hydroxyl protons by the radicals formed during polymer degradation.