Study on the Antioxidant Capacity and Kinetics of Polyolefin Antioxidant by Using DPPH Method

Free radical scavenging abilities of four polyolefin antioxidants were evaluated by DPPH· assay.The analysis of the scavenging reaction kinetics of the polyolefin antioxidant was carried out.The results showed that the four polyolefin antioxidants had good DPPH· scavenging abilities.The DPPH· scavenging rate of polyolefin antioxidant gradually increased with the increase of the antioxidants concentration,and increased first and then became steady along with the scavenging time.The antioxidation efficiency of the four polyolefin antioxidants from high to low was in order of antioxidant 1010,antioxidant 1098,antioxidant BHT,antioxidant 1076.The scavenging reaction of four polyolefin antioxidants to DPPH· fit a first-order kinetic reaction,and the reaction temperature has little influence on the reaction rate constant k and the activation energy Ea.The activation energy of the antioxidant 1010,whose scavenging ability was strongest in the four polyolefin antioxidants,was only 7.49 kJ/mol,showing that the scavenging reaction could proceed rapidly at room temperature.