聚合物稳定与降解（polymer stability and degradation）

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1、聚合物稳定与降解（Polymerstabilityanddegradation）Thefirstchapter,introduction1.theconceptofaging(degradation)Thestorage,processinganduseofpolymermaterialsintheprocessofchemicalproperties,physicalandmechanicalpropertieswillgraduallybecomeworse,knownasagingordegradation.P1Characteristic：Theinevitable,irreversi

2、bleprocess.Therelativelyshorttimescale.2.factorsthatleadtothedegradationofthepolymer(a)internalThecompositionandstructureofA.polymerchain.(1)differentcompositionanddegradationofdifferent(2)theactivitymaybethemaincauseofthedegradationofthematrix(3)theactivehydrogenismorelikelytobeseized(4)headtohead(

3、tailtail)structureofpolyolefinaremorelikelytobecomeactivepoints.(5)theeffectofmolecularweightchange:changesinthestructureofthemolecularweightoftheinternalrulesincreases,causingstability.Onthecontrary,iftheirregularstructureisreduced,increasedstability.(6)effectsofthemolecularweightdistribution:downa

4、widemolecularweightdistributionandstability.(7)thedegreeofbranchingeffect:thedegreeofbranchingincreases,theweaklinkinthemolecularchainalsoincreased,morepronetodegradation.TheaggregationstateofB.polymersThestabilityofamorphouspolymermateriallessthancrystallinepolymermaterialsThereason:amorphousmateri

5、als(lowdensitypolymerchainirregulararrangement),easytobeoxygen,water,chemicalinfiltration,degradation.3.impuritiesinpolymersInthetwokindsofpolymerimpurity:(1)asmallamountofimpuritiesmixedintheprocessoftheinevitable;(2)additive.Mostoftheimpuritieswillacceleratethedegradationofpolymers.(two)externalca

6、uses:EffectsofA.heat,temperatureandheatandoxygen:heatthepolymerchainscission,theformationoffreeradicals(reversible,bidirectional)hotoxygenpolymercrosslinkingordegradationofthematerialperformancedecline.EffectofB.lightEffectofC.oxygenandozoneoxygentopolymerdegradationinheatandlighteffect.Theozoneofun

7、saturatedbond(suchasrubber)thedamageisveryserious.EffectofD.wateranddampofwaterdissolvingandextractionofcomponents;hydrolysisandchainscission.EffectofE.andotherfactors:theeffectofmicroorganism;otheror