Polymer and Materials Science
Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
The chemical reactivities of novel reactive antioxidants based on tetrazoles for carbon-carbon double bonds of liquid polybutadiene and their antioxidation activities toward isoprene rubber were evaluated. These antioxidants, i.e., 2-substituted phenyl-5-(3′,5′ -di-tert-butyl-4′-hydroxyphenyl)tetrazoles (PHPT), were pyrolyzed in liquid polybutadiene at 160-170°C for 30 min to attach to rubber in extents of 61-85% of the nitrileimines formed from PHPT by 1,3-dipolar addition reaction. The reactivities of PHPT followed the order p-Cl 〉 m-Cl 〉 H 〉 p-CH3 〉 m-CH3, p-OC2H5, suggesting that PHPT reacts with diene rubber in electrophilic reaction and p-derivatives exhibit higher contents of binding than m-derivatives due to steric hindrance. From oxygen absorption data, the antioxidation activities of PHPT for isoprene rubber vulcanizates followed the order m-Cl, m-CH3 〉 H, p-Cl, p-Cl, p-CH3 〉 p-OC2H5. Isoprene rubber vulcanizates, obtained after pretreatment with PHPT by heating, were extracted with acetone, followed by aging to show that there was good retention and appreciable antioxidation activities of PHPT, especially, p-CH3 and p-Cl substituted PHPT.
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