Theoxidationbehaviorofthreebiodieselsofdifferentorigins,viz.rapeseedoilderivedbiodiesel,soybeanoilderivedbiodieselandwasteoilbasedbiodiesel,weretestedonanoxidationtester.Thechemicalcompositionsofthebiodieselswerecharacterizedbygaschromatography.Thereafter,thestructuraltransformationoffattyacidmethylester(FAME)ofthebiodieselswasanalyzedbyaninfraredspectrometerandanultravioletabsorptionspectrometer.TheresultsdemonstratedthattheoxidationbehaviorofbiodieselsofdifferentoriginswascloselyrelatedtothecompositionanddistributionofFAMEs.HigherconcentrationofunsaturatedFAMEwithmulti-doublebondsexhibitedpooreroxidationresistance.Furthermore,cis-transisomerizationtransformationoccurredintheunsaturatedFAMEmoleculesandconjugateddouble-bondproducedduringtheoxidationprocessofbiodiesel.Greatercis-transvariationscorrespondedtodeeperoxidationdegree.ThehigherthecontentofunsaturatedFAMEwithmulti-doublebondsinabiodiesel,themoretheconjugateddoublebondswasformed.
