Determination of Microrubber and N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamin Associated Transformation Products in Rubber Aging Process
N-(1,3-Dimethylbutyl)-N-phenyl-1,4-phenylenediamin(6-PPD)is a widely used antioxidant in tire rubber,which can be oxidized into a highly toxic compound 6-PPD quinone(6-PPDQ)by ozone,resulting in extreme acute toxicity in some fish species(e.g.,coho salmon).To explore whether 6-PPD can produce 6-PPDQ under natural light conditions,the experiment of the artificial accelerated xenon lamp aging test was designed.A self-made mechanical accelerated aging device of polymer materials was used to simulate aging tire rubber samples.Microrubber particles was determined.Then the associated transformation products of 6-PPD were analyzed and verified by chromatography-mass spectrometry after further xenon lamp aging test.The results showed that vehicles can produce smaller amounts of micro rubber on ideal road surfaces under lighter loads.The recovered tire rubber samples were changed into microrubbers.The size of microrubbers showed normally distributed with the average particle size of 4.12 μm.The antioxidant 6-PPD disappears after aging.After verification,it is found that 6-PPD can be changed into six transformation products under xenon lamp.They are 4-methyl-2-pentanone,N-phenylformyl-p-phenyldiamine(PFPDA),4-Aminodiphenylamine(4-ADPA),6-PPD-quinone,4-isopropylamino-diphenylamine(IPPD),and N,N'-diphenyl-p-phenylenediamine(DPPD),whose toxicities were predicted using T.E.S.T software.Except for DPPD and 4-methyl-2-pentanone,the median lethal dose of other products was higher than that of 6-PPD itself.This study shows that a large number of micronrubber particles are produced during vehicle driving,which has great significance for ecotoxicological evaluation of microrubber environment and safety and risk assessment of 6-PPD.
N-(1,3-Dimethylbutyl)-N'-phenyl-1,4-phenylenediaminAgingHigh resolution mass spectrometryMicrorubber
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