Synthesis And Antioxidant Activity Of Polyethylene Polyamine Bridged Hindered Phenols

A series of polyethylene polyamine bridged hindered phenols with different number of phenolic hydroxyl groups were synthesized by amidation condensation reaction using diethylenetriamine,triethylene tetramine and tetraethylene pentamine as bridged groups and using ?-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl chloride as antioxidant groups.The polyethylene polyamine bridged hindered phenols have been characterized by FT-IR and 1HNMR.The molecular structure of the hindered phenols is consistent with that of the designed hindered phenols.The antioxidant properties of polyethylene polyamine bridged hindered phenols were evaluated by the DPPH method.The results showed polyethylene polyamine bridged hindered phenols had a good scavenging ability on DPPH radical.With the increase of the concentration of phenolic hydroxyl and the reaction time,scavenging rate increased first and then almost kept constant.The chemical structures of the hindered phenols have a great influence on DPPH· scavenging ability.The results showed the number of phenolic hydroxyl groups and the ability donating protons to free radicals increased with increasing of the number of the amino groups,and the DPPH· scavenging activity increased.The effect of bridged type of the hindered phenols on DPPH· scavenging activity showed Irganox 1010 had the strongest DPPH· scavenging ability.The antioxidant properties of polyethylene polyamine bridged hindered phenols in high density polyethylene were tested,and the results showed that polyethylene polyamine bridged hindered phenols could effectively inhibit the oxidation of polyethylene during processing and thermal oxidation.With the increasing of the length of the bridged group,the melt flow rate,the tensile strength and the elongation at break of polyethylene adding polyethylene polyamine bridged hindered phenols decreased,and the oxidation induction time and the antioxidant properties increased.The antioxidant properties of the triethylene tetramine 1098 antioxidant is similar to that of the commercial Irganox 1010 with the same number of phenolic hydroxyl.The result of thermal oxidative aging showed that the carbonyl index of polyethylene adding hindered phenol antioxidants decreased with the increase of the length of the bridged group,and tetraethylene pentamine 1098 antioxidant had the strongest anti-thermal oxidative aging ability.Under high pressure thermal oxidative aging,the anti-thermal oxygen aging ability of commercial Irganox 1010 was the weakest.Under atmospheric thermal oxidative aging,Irganox 1010 and triethylene tetramine 1098 antioxidant had similar thermal oxidation resistance.