Immobilization of antioxidant on nanosilica and the antioxidative behavior in low density polyethylene

Nanosilica was firstly modified with an aminosilane coupling agent (AEAPS) and then reacted with the reactive antioxidant, 3,5-di-tert-butyl-4-hydroxycinnamic acyl chloride (AO-Cl), to form a nanosilica-immobilized antioxidant, AO–AEAPS–silica. FT-IR, XPS and TGA measurements confirmed that the reactive antioxidant was chemically immobilized onto the nanosilica surface. SEM observation showed that the nanosilica-immobilized antioxidant was homogeneously dispersed into the matrix of low density polyethylene (LDPE). It has been found that the antioxidative efficiency of AO–AEAPS–silica was superior to the corresponding low molecular counterpart (AO), based on the measurement of the oxidation induction time (OIT) of the LDPE/AO–AEAPS–silica and the LDPE/AO compounds containing equivalent antioxidant component. The release of the antioxidant from LDPE films was evaluated by monitoring the OIT change upon water extraction, demonstrating that AO–AEAPS–silica retained high stability against migration.