《轮胎氧化》PPT课件

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1、AREVIEWOFRUBBEROXIDATIONTheagingofrubbercausedbyoxidativedegradationleadstothedeteriorationinthephysicalandmechanicalpropertiesofvulcanizedrubbers.Thecriticalreviewwillcoverthemajordevelop-mentsinourunderstandingoftheoxidationofrubbers.ThemechanismsrelativetooxidationofrubberMethodso

2、fprotectionThemechanismsrelativetooxidationofrubberPolymerdegradationiscausedbychemicalbondscissionreactionsinmacromolecules.Theinitiationmodesofchemicaldegradationincludethermal,mechanical,photochemical,radiationchemical,biologicalandchemicaldegradationofpolymetricmaterials.Inaddition

3、,weofenfindtheagingphenomenonofwhite,crackedsurface,thedeteriorationofphysicalandmechanicalpropertiesintheprocessofrubberproductsused.TheagingofrubberisnotasimpleprocessThemechanismsrelativetooxidationofrubberR•+O2→RO2•(1)RO2•+RH→ROOH+R•(2)ROOH→RO•+•OH(3)RO•+RH→ROH+R•(4)RH+•OH→H2O+R•(5

4、)RO2•+RO2•→ROOR(stable)+O2(6)auto-acceleratedoxidationThemechanismsrelativetooxidationofrubberthelossofunsaturationofα,β-unsaturatedoxidizedproductsthroughcrosslinking:x-CH=CH-CH2-x-CH-CH-CH2-→׀׀-CH2-CH=CH-CH2--CH2-CH-CH-CH2-with:x=-C-,-C-OH,-C-,-C-H׀׀׀׀׀׀׀OHOOOoxidativecrosslinkingrea

5、ctionThemechanismsrelativetooxidationofrubbertheformationofanetherlinkagethroughphotooxidation:CH3CH3׀׀•C=C-CH-CH=C-CH2-→-CH-CH=C-CH2-------→׀׀+H•OOHO•CH3׀-CH-CH=C-CH2-׀O׀-C-CH-׀׀oxidativecrosslinkingreactionMethodsofprotectionOzoneattackonrubbercompoundscausescharacteristiccrackingper

6、pendiculartothedirectionofappliedstress.Thistypeofdegradationiscausedbyreactionsofozonewiththedoublebondsintherubbermolecules.Thesereactionsleadtochainscissionandtheformationofvariousdecompositionproducts.Thereareseveralmethodsofprotectionrubberfromoxidation.Howtopreventtheagingofrubbe

7、rBCABlockMethodReactionMethodPPDMethodsofprotectionMethodsofprotection——BlockMethodTheblockmethod(protectivefilm)reliesonthestabilizerfilmformedatthesurfaceofrubberthatpreventsozoneattackontherubber.waxMethodsofprotection——BlockMethodThekeyeffectsofawaxinrubberhavebeensummarizedasthe