Thermal-oxidative effect of a co-condensed nanosilica-based antioxidant in polypropylene

•Antioxidant immobilized on the surface of co-condensed nanosilica (SN-NH2).•The nano-antioxidant (SN-NH2-AO) exhibited good thermal stability.•SN-NH2-AO improved significantly the thermal-oxidative stability of polypropylene.•SN-NH2-AO exhibited excellent anti-extraction property.

Antioxidant in form of hindered phenol structure is commonly used to prolong the service life of polymer, while the low molecule antioxidant has defect for its low thermal stability and physical loss. Herein, the feasibility of using co-condensed silica immobilized antioxidant (denoted as SN-NH2-AO) to improve the thermal-oxidative stability of polypropylene (PP) was evaluated. Firstly, SN-NH2-AO was prepared by immobilization of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid (AO) on the surface of co-condensed silica (SN-NH2) which was synthesized by co-hydrolysis and condensation of tetraethoxysilane and aminopropyltriethoxysilane. Compared with AO, SN-NH2-AO exhibited higher thermal stability. Further, SN-NH2-AO was incorporated into PP by melt blending. The incorporation of SN-NH2-AO could not only disperse well in PP matrix but also improve the thermal-oxidative stability of PP distinctly. It was found that although the anti-oxidative efficiency of SN-NH2-AO was slightly inferior to AO, SN-NH2-AO exhibited superiority on anti-extraction property.

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