Effect Of Structure On Property Of Hindered Phenol Antioxidants In Polyolefin

Two antioxidants with dendritic structure and hindered phenolic groups were synthesizedwith butanediamine as core and hexanediamine as core by amidation condensation reactionwith β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl chloride and dendritic backbone of1.0generation PAMAM (poly(amido-amine)) as raw materials. The antioxidant1098analogueswere synthesized in the solvent of toluene with methyl-3-(3,5-ditert-butyl-4-hydroxyphenyl)propionate and ethylenediamine and butanediamine as raw materials, organic-tin as catalyst.The hindered phenolic antioxidants were characterized by FT-IR,1HNMR and MS, and theresult indicates the correctness of the product structure.The antioxidant properties of the new hindered phenolic antioxidants were evaluated byDPPH method and oxygen uptake measurement. The antioxidant properties of0.5generationPAMAM with tertiary amine structure were evaluated by the same method. The analysis ofthe scavenging DPPH·and ROO·reaction kinetics of them were carried out eventually. Theresults showed that at the same concentration of phenol hydroxyl group of antioxidant, theDPPH·scavenging activities of antioxidants were a positive correlation with phenol hydroxylgroup, reaction temperature, reaction time. With the methylene (-CH2-) of para-linking groupincreasing, the activation energy Ea of hindered phenolic antioxidants increase successively,the antioxidant properties of antioxidants weakened successively. At the same concentrationof phenol hydroxyl group of antioxidant, the activation energy Ea of dendritic antioxidantwith ethylenediamine as core was higher than others. Howerer, Ea of dendritic antioxidantwith butanediamine as core was higher than antioxidant1076and BHT, but lower than others.The Ea of dendritic antioxidant with hexamethylendiamine as core was higher than allantioxidants. The dendritic antioxidant with ethylenediamine as core exhibited goodantioxidant activities, and para-linking group had a great effect with antioxidant activities.At the same concentration of phenol hydroxyl group of antioxidant, theROO·scavenging activities of antioxidants were a positive correlation with phenol hydroxylgroup. With the methylene (-CH2-) of para-linking group increasing, inhibition rate constantkinhof hindered phenolic antioxidants decrease successively, the antioxidant properties ofantioxidants weakened successively. At the same concentration of phenol hydroxyl group ofantioxidant, the kinhof dendritic antioxidant were higher than others. However, at theconcentration of phenol hydroxyl group of2.0mM, the kinhof dendritic antioxidant wthbutanediamine as core and hexamethylendiamine as core were lower than antioxidant BHT, but higher than others. The0.5generation PAMAM exhibited antioxidant properties and withthe methylene (-CH2-) of para-linking group increasing, the antioxidant properties weakenedsuccessively. As novel kinds of intra-molecular complex primary antioxidants, the dendriticantioxidants combined with the structure characteristics of phenol and amine antioxidant,exhibited better antioxidant properties.