《轮胎氧化》PPT课件

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1、AREVIEWOFRUBBEROXIDATIONTheagingofrubbercausedbyoxidativedegradationleadstothedeteriorationinthephysicalandmechanicalpropertiesofvulcanizedrubbers.Thecriticalreviewwillcoverthemajordevelop-mentsinourunderstandingoftheoxidationofrubbers.Themechanismsrelativetoo

2、xidationofrubberMethodsofprotectionThemechanismsrelativetooxidationofrubberPolymerdegradationiscausedbychemicalbondscissionreactionsinmacromolecules.Theinitiationmodesofchemicaldegradationincludethermal,mechanical,photochemical,radiationchemical,biologicalandche

3、micaldegradationofpolymetricmaterials.Inaddition,weofenfindtheagingphenomenonofwhite,crackedsurface,thedeteriorationofphysicalandmechanicalpropertiesintheprocessofrubberproductsused.TheagingofrubberisnotasimpleprocessThemechanismsrelativetooxidationofrubberR•+O2

4、→RO2•(1)RO2•+RH→ROOH+R•(2)ROOH→RO•+•OH(3)RO•+RH→ROH+R•(4)RH+•OH→H2O+R•(5)RO2•+RO2•→ROOR(stable)+O2(6)auto-acceleratedoxidationThemechanismsrelativetooxidationofrubberthelossofunsaturationofα,β-unsaturatedoxidizedproductsthroughcrosslinking:x-CH=CH-CH2-x-CH-CH-CH

5、2-→׀׀-CH2-CH=CH-CH2--CH2-CH-CH-CH2-with:x=-C-,-C-OH,-C-,-C-H׀׀׀׀׀׀׀OHOOOoxidativecrosslinkingreactionThemechanismsrelativetooxidationofrubbertheformationofanetherlinkagethroughphotooxidation:CH3CH3׀׀•C=C-CH-CH=C-CH2-→-CH-CH=C-CH2-------→׀׀+H•OOHO•CH3׀-CH-CH=C-CH

6、2-׀O׀-C-CH-׀׀oxidativecrosslinkingreactionMethodsofprotectionOzoneattackonrubbercompoundscausescharacteristiccrackingperpendiculartothedirectionofappliedstress.Thistypeofdegradationiscausedbyreactionsofozonewiththedoublebondsintherubbermolecules.Thesereactionsle

7、adtochainscissionandtheformationofvariousdecompositionproducts.Thereareseveralmethodsofprotectionrubberfromoxidation.HowtopreventtheagingofrubberBCABlockMethodReactionMethodPPDMethodsofprotectionMethodsofprotection——BlockMethodTheblockmethod(protectivefilm)relie

8、sonthestabilizerfilmformedatthesurfaceofrubberthatpreventsozoneattackontherubber.waxMethodsofprotection——BlockMethodThekeyeffectsofawaxinrubberhavebeensummarizedasthe