复合材料教案6

TeachingTopicChapter6PolymernanocompositesLecturinghours180minTeachingObjectives1.Knowthegeneralfeaturesofpolymernanocomposites;2.Knowthepreparationmethodsofpolymernanocomposites;3.Knowthecharacterizationofpolymernanocomposites.TeachingEmphases1.Thefeatureofpolymernanocomposite.2.Thepreparationofpolymernanocomposite.TeachingDifficultPointsThecharacterizationofnanocomposites.TeachingMethodsLecturing+PPT+discussion+interactionTimeArrangementTeachingcontent45min6.1Introduction1.definitionWheninorganicphasesinorganic/inorganiccompositesbecomenanosized,theyarecallednanocomposites.Organic/inorganicnanocompositesaregenerallyorganicpolymercompositeswithinorganicnanoscalebuildingblocks.2.Advantagesinorganicmaterialorganicpolymer3.Definingfeatureofpolymernanocompositesthesmallsizeofthefillersleadstoadramaticincreaseininterfacialareaascomparedwithtraditionalcomposites.Thisinterfacialareacreatesasignificantvolumefractionofinterfacialpolymerwithpropertiesdifferentfromthebulkpolymerevenatlowloadings.4.InorganicnanoscalebuildingblocksNanotubes;Layeredsilicates(montmorillonite,saponite),Nanoparticlesofmetals(Au,Ag),Metaloxides(TiO2,Al2O3),Semiconductors(PbS,CdS),Others.5.Polymer/SilicaSiO2isviewedasbeingveryimportant.Polymer/silicacompositesarethemostcommonlyreportedintheliterature.Theyhavebeenemployedinavarietyofapplications.6.Discuss:whatisnanocomposite?6.2PreparationofnanocompositeOrganicorinorganicpolymerizationgenerallybecomesnecessaryifatleastoneofthestartingmoietiesisaprecursor.Blendingisgenerallyjustmixingofthesilicananoparticlesintothepolymer;asol-gelprocesscanbedoneinsituinthepresenceofapreformedorganicpolymerorsimultaneouslyduringthepolymerizationofthemonomer(s);themethodofinsitupolymerizationinvolvesthedispersionofnanosilicainthemonomer(s)firstandthenpolymerizationiscarriedout45min6.2.1Blending6.2.1.1MeltblendingMeltblendingismostcommonlyusedbecauseofitsefficiency,operability,andenvironmentalcontainment.Matrices:PolymersandpolymerblendsLevel:lessthan3vol%manyadvantages:beingsimple,lowcost,easytocontrolandbroadlyapplicable.6.2.1.2.SolutionBlendingSolutionblendingisaliquid-statepowderprocessingmethodthatbringsaboutagoodmolecularlevelofmixingandiswidelyusedinmaterialpreparationandprocessing.Someofthelimitationsofmeltmixingcanbeovercomeifboththepolymerandthenanoparticlesaredissolvedordispersedinsolutionbutatacostdependingonthesolventanditsrecovery.Thelocationforsolutionblendingisnotlimitedtoasolutioncanincludealatexorasuspension.andthencompressionmoldingisalsoapplied.6.2.1.3OtherBlendingMethodsToovercometheseproblemsis:toprocessthepolymerinthesolidstate,whichavoidsthethermalandsolventproblemsencounteredwithtraditionaltechnologieswhileprovidingalmostinfinitedesignflexibilityandprocessingsimplicity.6.2.2Sol-GelProcessSol-gelreactionisamethodtoprepareceramicprecursorsandinorganicglassesatrelativelylowtemperatures.Themajoradvantageoftheprocessisthatmildconditions,suchasrelativelylowtemperatureandpressure,areusedinthistypeofprocessingofceramics.thesol-gelprocesscanbeviewedasatwo-stepnetworkformingprocess:thefirststepbeingthehydrolysisofametalalkoxidethesecondconsistingofapolycondensationreaction.Thepropertiesoftheresultingnanocompositesinfluencedbyparticlesizesandinteractionbetweenthedispersedandcontinuousphases.Accordingtothenatureofinterfacialinteraction,hybridmaterialscanbedividedintotwodistinctclasses,6.2.3InSituPolymerization6.2.3.1.GeneralPolymerizationThereareseveraladvantagesofusingtheinsitupolymerizationmethod.Theseinclude:easeofhandling,thespeedoftheprocess,andbetterperformanceofthefinalproducts.Theprocessofinsitupolymerizationinvolvesthreecontinuoussteps:Themostimportantfactorsthataffectthepropertiesofcompositesare:thedispersionandtheadhesionatthepolymerandfillerinterfaces.Inorganicparticlesmaydispersehomogeneouslyinthepolymermatriceswhentheyarepremodifiedbyacouplingagent.6.2.3.2PhotopolymerizationItisaprocesswhereUVlightinducesthepolymerformationallowingafasttransformationoftheliquidmonomerintothesolidfilmwithtailoredphysicochemicalandmechanicalproperties.Intheprocess,radicalorcationicspeciesaregeneratedbytheinteractionoftheUVlightwithasuitablephotoinitiator,whichinducethecuringreactionofreactivemonomersandoligomers.6.2.3.3Surface-InitiatedPolymerizationAkeyfeatureintheconstructionofnanocompositesystemsisthedevelopmentofspecificinteractionsattheinterfaceoftheorganicandinorganiccomponents,becausetheinterfaceplaysadominantroleinthepreparationandpropertiesofnanocomposites.Therefore,thedevelopmentofgraftingstrategiessoastotailorthesurfacepropertiesofmineralsubstratesisofgreatcurrentinterest.6.3ColloidalNanocompositesThesematerialsrepresentanewcategoryofnanocomposites,whichcanexhibitremarkableproperties(mechanical,electrical,optical,chemical,rheological,etc.)byanappropriatecombinationandstructurationoftheorganicandinorganiccomponentsinsidethenanoparticles.Colloidalpolymer/silicananocompositesPrincipallycolloidalpolymer/silicananocompositescanbedividedintosy