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Dec.2008,Volume2,No.12(SerialNo.13)JournalofMaterialsScienceandEngineering,ISS

    N1934?8959,USA

    ;Rulesinsynthesisandstructuraldesignofwaterborne

    ;polyurethanemodifiedwithacrylicresin

    ;,’r,

    ;LIZhihua.LUJian—ti’

    ;fiKeyLaboratoryofNonferrousMetalMaterialsScienceandEngineeringofMinist~ofE

    &tcation.Changsha410083.China

    ;2.SchoolofMater’ialsScienceandEngineering,CentralSouthUniversi~,Changsha4100

    83,China)

    ;Abstract:Aseriesofpolymers:PUA,PUA’andPU/PA,which

    ;preparedbywaterbornepolyurethane(PU)modifiedwith ;acrylicpolymer(PA),canbeformedbydifferentpolymer ;modifvingmethodsofchemica1andmechanica1blend.With ;mechanicallymixing.thecommixingdegreebetweenPU ;molecularchainandPAmolecularchaincanonlyreacha ;limiteddegree;butwithchemicalblendwhichcouldform ;chemicalbondbetweenPAandPUmolecularchain,the ;compatibilityandcommixingdegreebetweenPUmolecular ;chainandPAmolecularchaininPUAcanbeimproved ;apparently.Ifthecoreshellpolymerizationandchemicalbond ;areca~iedoutbetweenPUandPAmolecularchain,the ;compatibilityandcommixingdegreewillincrease,and ;microphasewillbeformed.whichmakethematerialpossess ;excellentperformance.

    ;Keywords:waterbornepolyurethane;acrylicresin;synthesis; ;structure:rules

    ;1.Introduction

    ;Itisimportanttosynthesizeahighperformance ;waterbornepolyurethanethroughtheorganic

    ;combinationbetweenpolyurethaneandacrylicresin. ;Inthisway,theoverallperformanceofthematerials ;canbeimprovedeffectively【一.Atpresent,blend,

    ;co’polymerizationorgraftbetweenpolyurethaneand

    ;acrylicresinundercertainconditionarethemajor ;methodstoimprovewaterbornepolyurethane[1.A

    ;chemicalbondbetweenthePUandPAmolecularchain ;canbeformedinthefilmsofthewater.borne

    ;polyurethane(PU)modifiedwithacrylicresin(PA)11.

    ;Inordertoimprovethecompatibilityandenhancethe ;C0rrespondingauthor:LIZhihua(1963),male,associate

    ;professor;researchfield:macromoleculematerials.Email:

    ;ligfz@mail.CSU.edu.cn.

    ;degreeofthecommixingdegreebetweenPUandPA, ;theNH2terminatedpolyurethane(PU)molecularand ;theacrylicpolymer(PA)containingtheradiclewhich

    NH2weresynthesized.The ;canreactwith

    ;waterbornepolyurethanemodifiedwithacrylicresin ;wassynthesizedbymechanicalblend,chemicalblend ;andgraftpolymerizationbetweenPUandPA(orPA’),

    ;andtheirstructuraldesignsandruleswerealso ;discussed.Theresultsindicatedthattheprocedureof ;acrylicemulsionpolymerizationinpolyurethane ;dispersionbychemicalcommixingwasacoreshell

    ;polymerization[4,7-81

    ;,andthemicrophaseseparation

    ;wasformedbetweenthetworesinmoleculechains ;whichmadePUandPAmoleculechainpossessbetter ;compatibilityandhighdegreeofmixing. ;2.Experiments

    ;AconventionalmethodwascarriedoutInacrylic ;emulsionpolymerization.Twotypesofacrylic ;emulsionweresynthesized.Onlyone(PA)ofthemcan ;reactwithNH2inPU.Polyurethanedispersionswere ;alsopreparedaccordingtoconventionalway.Some ;chemicalreagentsusedintheexperiment,suchas ;acrylicacid,methacrylate,phenylethylene,sodium ;dodecylsulfonate,OPandK2S208etc.,wereanalytical ;regentgrade.

    ;2.1Preparationofcomplexpolymersystem ;Acrylicemulsionpolymerizationwascarriedout ;ina500mLfourneckedglassflaskequippedwith

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    ;ructuraldesignofwater-bornepolyurethanemodifiedwithacrylicresin

    ;Mixtureofpolyurethanedispersion,emulsifier,acrylic ;acid,methylmethacrylate,styreneetc.,werecharged ;intothereactorwithadroppingfunnelfor3hours,the ;complexpolymersystemwasfinallyformedafterheat ;preservationfor1hour.Thegraftpolymer,PUA,was ;synthesizedbecauseacrylicmonomerscontainingthe ;radiclewhichcanreactwithNH2-,PUandPA

    ;molecularchaincouldalsoformchemicalbondinPUA ;Whiletheacrylicmonomerscontainingradiclewhich ;canreactwith-NH2-wasnotused,achemicalblend ;polymer,(PUA’)wasformed,butPUandPA’

    ;molecularchaincouldnotformchemicalbondin ;PUA’.

    ;AmechanicalblendpolymerfPU/PA)withbright ;fluorescencewasformedbymechanicallymixing ;betweenPt,andPAemulsion

    ;2.2Measurements

    ;Theparticlesizeandthedistributionofemulsion ;weretestedwithexcitingscatteringparticlesize ;analyzer(BI900),andthetherma1behaviorsofthe ;polymerweremeasuredwithdifferentialthermal ;analyzer(Dupont1090).

    ;3.Resultsanddiscussion

    ;3.1ParticlesizeanddistributiOnofthe ;emulsions

    ;Themeasurementresultsoftheparticlesizeand ;thedistributionofPA,PU,PU/PA,PUA,PUA’

    ;emulsionswerelistedinTable1.

;Table1Particlesizeanddistributionofthecolloidalparticle

    ;Notes:DIisvolumemediandiameter;DEisvolumeaveragediameter

    ;AccordingtoTablel,thesizeofcollidedparticle ;ofPU/PAwasmuchsmallerwhenPUandPAwere ;mixedmechanically,andthesizedistributionwas ;concentrativewithlessimprovement.Thoseshowthat ;coalescencebetweenthecolloidalparticleofPUand ;PAisverylimitedandthesystemofPU/PAhasa ;strongmixingstability.ThedistributionOfPUAor ;PUA’isconcentrative,andtheparticlesizeenlarged

    ;noticeably.Sowecanconcludethattheemulsion ;polymerizationisalatexpolymerizationprocesswhen ;thePUemulsionparticleactedasaseedemulsionand ;theacrylicresinmonomerswelledintothe ;polyurethane.SOPUAandPUA’canbeconsideredas

    ;coreshellpolymerizationstructure.

    ;3.2DSCanalysisofmaterials

    ;26

    ;Thethermalbehaviorofpolymerwasstudiedby ;DSC,andtheDSCcurvesofPUandPA’wereplotted

    ;inFig.1.

    ;AccordingtoFig.1.PUhastwoglass

    ;transformationtemperatures:one(tgl10.7?)ofthe

    ;softsegment,andtheother(tg2=94.C)ofthehard ;segment.Itshowsthatmicrophaseseparationstateis

    ;formedbetweenthesoftandthehardsegmentof ;polyurethane(PU).Thereisalargeendothermicpeak ;170~CinPU,whichisanorderlystructureformedby ;CoulombforceandhydrogenbondinPU.Itisabove ;theorderstructuretransformationintodisorder ;structure.AccordingtotheDSCcurveofPA,ithas ;onlyoneglasstransformationtemperature ;ftgl=-1.1?).Itshowsthatacrylicresincouldforma ;disordercopolymeranditsstructureissinglephase. ;Rulesinsynthesisandstructuraldesignofwater-bornepolyurethanemodifiedw

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    ;Fig.1TheDSCcurvesofPUandPA

    ;TheDSCcurvesofPUA,PU/PAandPUA’were

    ;plottedinFig.2.AccordingtoFig.2,foreachofthese ;threepolymersthereisalargeandsharpstepbetween ;.

    lO?.Inaddition.bothPUAandPU/PA ;40?and

    ;haveasmallstep.whichistheglasstransformation ;betweenthesoftsegmentandthehardsegment.This ;smallglasstransformationinPU/PAismoreobvious ;thanthoseofPUAandPUA’,whichrevealsthatthe

    ;softsegmentofPUinPU/PAandthemoleculechainof ;PAforlTltheirownphase.Thismeansthatthedegreeof ;commixingaboutthesoftsegmentofPUandacrylic ;moleculechaininPU/PAislowerthanthoseinPUA ;andPUA’.Thisalsorevealsthatwhentheemulsionsof

    ;PUandPAaremixedmechanically.thetwiningand ;commixingbetweenPUandPAmoleculechainonly ;takeplaceontheparticlesurfacewithalimiteddegree ;commlxlng.

    ;Betweenl0?andl00.Cthereisasharpstepin

    ;DSCcurveofPUA’andapparentphasetransformation

    ;temperature(t=92~C)inhardsegmentofPU.Though ;thesamestepcouldnotbeobviouslyobservedincurve ;ofPUAorPUPA.thecurvesofPUAandPU/PA

    ;declinedstraightlyinthesametemperaturerange.So ;wethinkthattheglasstransformationsalsoexistin ;PUAandPU/PA.whiletheglasstransformationof ;PUAsmoreobviousthanthoseofPUAandPU/PA. ;Thisnotonlyindicatesthatthecompatibilitybetween ;thesoftsegmentofPUmoleculechainandacrylicresin ;(PA’)moleculechainisverylittleandthedegreeof

    ;microphaseseparationishigh,butalsorevealsthatthe

    ;chemicalbondexistsbetweenthehardsegmentofPU ;moleculechainandthemoleculechainofPAsoasto ;increasethecompatibilityandthecommixingdegree ;betweenthehardsegmentofPUmoleculechainand ;PAmoleculechainOfPUAorPU/PAgreatly. ;0OeO12O160200240

    ;Temp~-ratII(?l/?

    ;Fig.2TheDSCcurvesofPUA,PU/PA,PUA

    and180?.thereisanendothermicpeak ;At100?

    ;whichshowstheorderingofthehardsegmentofPU ;existsinPUAandPU/PA.Thisrevealsthat ;microphaseseparationexistinPUandPAmolecule ;chainofPUAorPUA’materials.Italsomeansthat

    ;PUAorPUA’designedhavethestructureofcore—cell

    ;typepolymerandourstudyreachaimofmaterial ;designs.

    ;Theendothermicpeaktemperature(152~C)of ;PUAinDSCcuresislowerthanthattemperature ;(155?)ofPUA’,whichshowsthattheorderdegreeof ;PUA’isalsolowerthanthatofPUA.Thelowerorder

    ;degreemeansthatachemicalbondexistsbetweenthe ;hardsegmentofPUmoleculechainandPAmolecule