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MeTHPA epoxy resin

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MeTHPA epoxy resin

    MeTHPA epoxy resin

    J.Cent.SouthUniv.Techno1.(2007)06075306

    D0I:l0.1007/sll77l-007-0l43-8

    Structuralcharacteristicsandpropertiesof

    PU-modifiedTDE-?85/MeTHPAepoxyresin

    LIZhihua(李芝华),KEYupeng(柯于鹏),RENDongyan(仃冬

    ),ZHENGZi.qiao(郑了樵)

    Springer

    (SchoolofMaterialsScienceandEngineering,CentralSouthUniversity,Changsha410083,China)

    Abstract:Diglycidyl4,5epoxycyclohexanel,2-dicarboxylate(TDE

    85)/methyltetrahydrophthalicanhydride(MeTHPA)epoxy

    resinwasmodifiedbypolyurethane(PU).anditsstructuralcharacteristicsandpropertieswerestudiedbyinaredspectrumanalysis

    (IR1,scanningelectronicmicroscopy(SEM),mechanicstestingandthermogravimetricanalysis(TG).Theresultsindicatethatepoxy

    polymericnetworkIandpolyurethanepolymericnetworkIIareformedinthePU

    modifiedTDE85/MeTHPAepoxyresin.

    MeanwhilethePUmodifiedTDE

    85/MeTHPAresinshaveheterogeneousstructure.Themiscibilitybetweenepoxy(EP1and polyurethane(PU1aswellasthephasesizearedominantlydeterminedbythemassfractionofpolyurethaneprepolymer(PUP)inthe

    EP/PUblends.WiththeincreaseofPUPmassfraction.thetensilestrength.impactstrengthandthermalstabilityofthePUmodified

    TDE

    85/MeTHPAepoxyresinallfirstlyexhibitincreasingtendency.anddecreaseaftersuccessivelyreachingtheirmaxima.When

thenumber-averagemolecularmassofPPGisl000andthemassfractionofPUPis15%.theten

    silestrength.impactstrengthand

    thermalstabilityofmaterialsobtained.comparedwithTDE

    85/MeTHPAepoxyresin.areimprovedobviously. Keywords:TDE

    85;polyurethane;interpenetratingpolymericnetwork;mechanicalproperty;thermalstabili

    ty

    lIntr0ducti0n

    Theeyecatchingdiglycidyl4,5-epoxycyclo

    hexane1.2-dicarboxylate(TDE.85)epoxyresinhas manyadvantagessuchassmallviscosity,highactivity, goodthermalstabilityandhighstrength.whichmakeit havesuperiorityoverothermaterialstobeusedinthe fieldsasthermalresistantcoatings.compositesand adhesivesl-Zj.However.crackingatlowtemperatureand badimpactingresistancehaveinhibiteditfrom applicationforhighermaterialsrequirement.Improving thetoughnessandlowtemperatureworkpropertyof TDE.85willbethekeydirectionoffutureresearches. whichcertainlyhasabrightlydevelopingforeground. Generaltoughnessincreasedmodificationstoepoxy

    resinfEP1areatthecostofsacrificingitsstiffnessand thermalstability.Interpenetratingpolymericnetwc)rks (IPNs)technique,sinceitsadvantage,hasbeenattracted widerecognitionfortheirsynergisticeffectthatresultsin superiortensilestrength.impactstrengthandthermal stabilitythaneitheroftheseparatedcomponent.EP

    modifiedbyPUcanimprovebothstrengthand

    toughnessbecauseoftheformationofIPNs,which possesstwoseparatedbutinterlockednetworksunder

properexperimentalconditions【一….Therefore.the

    studyingontheIPNsofPUmodifiedTDE.85/MeTHPA

    resin,alongwiththeirdesigning,isthedevelopment directionandsignificantmeansofTDE85modification.

    InitiatingstudyonPU..modifiedTDE..85/MeTHPAresin couldobtaintheoreticalsupportsforthedesignOfIPNs intheresinsystem.whichsurelyhasespecial significance,Uptothepresent,thoughsignificant progressesofthedesign.characterizatiOn.and applicationofthematerialsbasedonTDE.85havebeen made1-15/,

    the1iteraturecoveringonTDE85/MeTHPA

    modifiedbyPUhasbeenrarelyreported.Thereforea seriesofPU..modifiedTDE..85/MeTHPAresinswere preparedfrompolypropyleneglycol(PPG)withthe number-averagemolecularmassOf1000.Andthe structuralcharacteristicsandpropertiesofthe modifiedsystemsandtheirmodificationlawswere djscussed.

    2Experimental

    2.1Materiais

    Diglycidyl4,5epOxycyclOhexane1,2-dicarboxylate

    (TDE.85)waspurchasedfromTianjinJindongChemical Plant(Tianjin,China).Methyltetrahydrophthalic anhydride(MeTHPA)wasfromWenzhouQingming ChemicalPlant(Wenzhou,China).2,4toluene

    diisocyanate(TDI)wasprovidedbyShanghaiShiyi ChemicalAgentCo..Ltd.(Shanghai.China). Polypropyleneglycol(PPG)withnumber-average molecularmass(Mn,ofl000waspurchasedfrom

Receiveddate:2007——03——20;Accepteddate:2007——05——25

    Correspondingauthor:LIZhihua.PhD;Tel:+8673I8830838;E

    mail:ligfz@mail.CSUedu.cn

    754J.Cent.SouthUniv.Techno1.2007,I4(6) TianjinNo.3PetrochemicalFactory(Tianjin,China). 1,4buranediol(1,4-BDO)andtrimethylolpropane(TMP) weresuppliedbyChinaMedicationShanghaiChemical AgentCo.,Ltd.(Shanghai,China).2,4,6tris

    (dimethylaminomethyl1phenol(DMP30)wasobtained fromChangshaChemicalResearchInstitute(Changsha, China).

    2.2Experimentalprocess

    2.2.1SynthesisofisocyanateterminatedPUP

    PPGofproperquantitywasfilledintoacleanand driedfour-neckflask.andstirredat120?forlhto

    dehydrate.Thenitwascooleddowntoaround50?and

    stoichiometricquantityofTD1wasadded.Themixture understirringwasgraduallyheatedtoabout80?and

    maintaineduntilthereactionwascompleted.Then isocyanateterminatedPUPwasobtained.

    2.2.2Castundervacuum

    Mouldscoatedwithantistickingagentwerekeptin thefurnaceat80?forfurtheruse.TDE85and

    MeTHPAwereseparatelydriedundervacuumof0.009 MPaat80?for2h.thencooledto60?.TDE85and

    isocyanateterminatedPUPobtained.1.4B0Das

    chainextendedagent,TMPascrosslinkedagent,

    MeTHPAascuringagentandDMP30ascuring

    accelerantaccordingtoproperproportionwereadded

    intothevacuumcastingmachine.Themixturewas stirredandheatedforacertaintime,thencastedintothe moulds.Theresincuredafteraseriesofprocessesas procedureheatingsolidificationf120?/2h+140?/2h

    +160?/2h,.

    2.3Characterization

    ThecuringreactionwassurveyedbyNicolet

    R360typeFT-Rspectrometer.Curedsamples

    wereanalyzedusingtheKBrpellettechniqueandliquid samplesweredirectlyanalyzedorafterdilutedbyCCh. Scanningelectronicmicroscopy(SEM1wasdone onaFEISirion200typefieldemissioninstrumentto detectthemicromorphology.Fracturesurfaceof fleshbrokensamplewasfirstlyetchedby

    dimethylformamide.thentookmetalspraying.Thenthe samplewasfixedonametalsubstratebyconductive adhesivetapebeforeexamination.

    Tensilestrengthwasrecordedonacomputer. controlledelectronicuniversalmachine(SANA. CMT51051accordingtoGBl04079,andimpact

    strengthwasperformedbyJB5typeimpacttesting

    machineofWuzhongMaterialTestingMachine CompanyaccordingtoGB104379(unnotchedsamples),

    respectively.Afterimpactstrengthtestfracturesurface morphologywasdetectedusingSEMfKYKY-2800). ThermalstabilityofEPwascharacterizedby thermogravimetricanalysisonaninstrument(SDTQ600, USA).TGcurveswererecordedunderthefollowing operationalconditions:temperaturesrangefrom30to

600?,heatingrate10~C/minandinair.

    3Resultsanddiscussion

    3.1Infraredspectra

    InflaredspectraofTDE85.PUPandTDE

    85/MeTHPAresinsamplesareshowninFig.1.The

    NC0groupcharacteristicabsorptionpeakofPUPat about2270cm..disappearsintheinfraredspectrumof PUmodifiedTDE85/MeTHPAsamples.sodoesthe

    whichconfirmthat epoxygroupofTDE.85at908cm(

    isocyanategroupsofPUPandepoxygroupsinTDE85

    resinhavereactedcompletely.

    ThesystematicstudyinRefs.14-151indicatedthat

    duringthecuringprocessofPUmodified

    TDE.85/MeTHPAepoxyresin(PUmodifiedEP),epoxy

    polymericnetworkIisformedthroughreactionbetween TDE.85andMeTHPA.andPUpolymericnetworkIIis generatedbythechain..extendedandcross..1inked reactionsamong1,4BD0,TMPandPUprepolymer.

    Wavenumber/cm

    Fig.1IRspectraofTDE85,PUPandPUmodified

    TDE85,MeTHPAresins

    3.2Micro-morphology

    Miscibilityofthepolymersandcharacteristicsof morphologyweresurveyedbyfieldemissionSEM. ThroughSEMsurfaceobservationdiphasedistribution andinterpenetratingextentbetweenPUandEPwere detected.PUPwassynthesizedfromPPG(=10001 and2.4TDI.Fig.2showsSEMimagesofTDE85/

    MeTHPAepoxyresinsmodifiedwith0,5%,10%,15%, 20%,25%(massfraction1ofPUP,respectively.

AsshowninFig.2.TDE85/MeTHPAresinhasa

    unilateralcontinuitymorphology(Fig.2(a)),while PUmodifiedTDE.85/MeTHPAepoxyresinshave

    diphasestructureandexhibitobviousdifferencesin conformitywithvariousPUPmassfractions.Figs.2fb1 and(c1illustratethatwhenthemassfractionofPUPis low.PUphaseisuniformlydispersedinthecontinuous

LIZhihua,etal:StructuralcharacteristicsandpropertiesofPUmodifiedTDE

    85/MeTHPAepoxyresin755

    Fig.2SEMimagesofsampleswithdifferentmassfractionsofPUP MassfractionofPUP:(a)0;(b)5%;(C)10%;(d)15%;(e)20%;(f)25% EPphase,appearingdistinct"island''structureandphase interface.WhenmassfractionofPUPiSl5%.asshown inFig.2fd),therearealmostnophaseinterfacesand phaseseparationisfairlyobscure,suggestingthat interpenetratingnetworkshavebeenformedatthepoint ofphaseinterfacewithhighlevelofinterpenetrationand mutualtangling.WhenthemassfractionofPUPreaches 20%,ascanbeseeninFig.2(e),phaseseparationdegree andphasesizeincreaseslightly.Whenmassfractionof PUPreaches25%,asshowninFig.2m,withthe

    incrementofmassfractionofPUPanditslagerspace continuity,thephaseinterfacebecomesclearerandphase sizeincreasesconspicuously,whichmeansthatthe diphasemiscibilitydecreasesandphaseseparation evidentlyoccurs.

    TheanalysisabovedemonstratesthatPUmodified

    TDE85/MeTHPAresinhasadiphasestructureand massfractionofPUPiSthemainfactorthatinfluences

    themiscibilityandphasesizeofPU/EPsystem.There areobviousdifferencesirlthemicromorphologyof

    PUmodifiedTDE85/MeTHPAresinwhenvariousmass fractionsofPUareintroducedintoinsystem.Witha propermassfractionofPUPaddition(accountingfor grossmassofthesystem).therearehighlevelof interpenetrationandmutualtanglingbetweenPUandEP atthepointofphaseinversioninmaterialobtained. whichshowscharacteristicofEP/PUIPNs.

    3.3Meehaniealproperties

    VariationtendencyinthemechanicalpropertiesOf TDE85/MeTHPAepoxyresinmodifiedbyPUiS

    presentedinFig.3accordingtodifferentPUPadditions. Ascanl,beseeninFig.3.whenthemassfractionofPUP a~ivesat15%.thetensilestrengthofmaterialobtained iS6939MPa.exhibiting48.0%increase.andimpact strengthiS23.56kJ/mwithll5%increase.Whenthe PUPadditioniSsmal1.mechanicalpropertiesof PUmodifiedTDE85/MeTHPAresinshowanuprising tendencyaccompaniedwithincreaseofPUPaddition. Tensilestrengthandimpactstrengthreachtheirclimaxes

756J.Cent.SouthUniv.

    Techno1.2007.14(6)

    MassfractionofPUP/%

    26

    22

    l8

    networkwhenstressed.withoutstresstransferbetween direntnetworks.ButforPU.modifiedEPitiSin

    anothercasebecauseoftheformationofIPNsbetween zPUandEP.Thereuponthestresscanbedetractedand theextemalforceandmoreexterna1WOrkareneededto damagetheIPNstructure.whichexhibitstherising e

    e-0tendencyofmechanicalpropertiesi.e.tensilestrength ^l一一

    andimpactstrength.

    I4

    

    l0

    Fig.3EffectofmassfractionofPUPinEP/PUontensile strengthandimpactstrengthofsamples

    successively.Thereafterbothofthemdecreasewith furtherincreasingofmassfractionofPUP.

    Propertiesofmaterialsaredeterminedbytheir structures.ForEPsystem,deformationoccursinEP 3.4Fracturesurfacemorphologyanalysis

    Fig.4showstheSEMfractographsforsamplesafter impacttests.AscanbeseeninFig.4.TDE85/MeTHPA

    epoxyresindenotedassample(a)hasabasicallyplane, smoothandlevelfracturesurface.Thecrackslinearly extendinthesamedirection.indicatinglinlestress sca~eringandbaddynamicductility.Samplesfrom(b)to (DarePUmodifiedTDE85/MeTHPAresins.Their

    fracturesurfacesarequiteragged,andbreachesare relativelyroundingoff,andcracksarenomoreinthe samedirectionbutscattering.SOitcanbeinferredthat impactpropertyhasbeenimproved.

    Fig.4SEMimagesoffracturesurfacesofsampleswithdifferentmassfractionsofPUP

    MassfractionofPUP:(a)0;(b)5%;(C)l0%;(d)15%;(e)20%;(D25% \LI_lJ_?0II?

LIZhihua,etal:StructuralcharacteristicsandpropertiesofPUmodifiedTDE

    85/MeTHPAepoxyresin757

    WhenmassfractionofPUPissmal1.asshownin

    Figs.4(b)and(c),thecrackschangefromstraightlinesto curvesdivergingtoaseriesofdirections.andthelength ofcracksincreasesaccordingly.Meanwhilefracture surfacesinthetwoimagesbecomewel1.bedded.which alsosuggestsimprovedtoughness.Withfurtheraddition ofPUP'asshowninFigs.4(d)and(e),fracturesurfaces becomerougherandthecracksarrangeirregularly, exhibitingparalleledandcrossed.Whentheresinsystem isimpacted.thiskindofstructureguaranteesthatmore energYcanbeeffectivelyabsorbed,morestresscanbe detracted.Thusimpactpropertyisfurtherupgraded. Comparedwithsamples(d)and(e),uniformityofcrack distributioninFig.4fdeclines,sodothenumberof smallcracksandroughnessofthefracturesurface.The ef-fectofmodificationbyPUonTDE85becomesworse.

    Fromtheanalysisabove.itisinferredthatwiththe additionofPUP.thefracturesurfacesofPU.modified TDE.85/MeTHPAresinchangetoberoughfromsmooth andthecrackstuITItobecomplexcurvesfrom

    approximatestraightlines,whichshowthe

    characteristicsofductilerupture.

    3.5Thermalstability

    TGcurvesofsamplesareshowninFig.5.Ascanbe seeninFig.5.samplewitha15%massfractionofPUP

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