strength improvement of polypropylene threads modified by PVA C

MaterialsLetters62(2008)4380–4382ContentslistsavailableatScienceDirectMaterialsLettersjournalhomepage:/locate/matletMechanicalstrengthimprovementofpolypropylenethreadsmodifiedbyPVA/CNTcompositecoatingsBoZhao⁎,JingWang,ZijiongLi,PingLiu,DaChen,YafeiZhangNationalKeyLaboratoryofNano/MicroFabricationTechnology,KeyLaboratoryforThinFilmandMicrofabricationoftheMinistryofEducation,ResearchInstituteofMicro/NanometerScienceandTechnology,ShanghaiJiaoTongUniversity,Shanghai200030,PRChinaarticleinfoabstractPoly(vinylalcohol)/carbonnanotube(PVA/CNT)compositewaallcarbonnanotubes(MWNTs)weretreatedinacidandalkalitogetwater-solublenanotubes,andthenembeddedintopoly(vinylalcohol)(PVA)matrix,resultinginpolymer–ess–strainmeasurementsshowthatthetensilestrengthandtoughnessofthePVA/CNTcoatedthreadincreasedby117%and560%,esultsaresupportiveofgoodinterfacialbondingbetweenthecarbonnanotubes(CNTs)andpolymermatrix.©ehistory:Received29July2007Accepted24July2008Availableonline26July2008Keywords:uctionCarbonnanotubes(CNTs)havereceivedmuchattentionbecauseoftheiruniquemechanical,thermalandelectricalpropertiessincetheirdiscoverybyIijimain1991[1].TheoreticalandexperimentalstudieshaveshownthatCNTspossessaYoung'smodulusof1TPaandatensilestrengthof63GPa[2,3].Asaresult,theCNT-basedcomposites,whichmaybeoneofthemostpromisingapplications,havebeenintensivelystudiedusingdifferentmatrixmaterials,polymers[4,5],ceramics[6,7]andmetals[8].Inthefabricationofhigh-qualitypolymer–carbonnanocompositeswithpredictableandoptimalperformance,pressiveresultsofstrengthandtoughnessincreasehavebeenobtainedforpoly(vinylalcohol)(PVA)compositefibers,wheregreatcarewastakentoachieveagooddispersion[9].Inthispaper,wereporeadisobtainedbycoatingthepolypropylenethreadwiththePVA/lubleCNTsareusedtofacilitatetheirdispersioninthePVAmatrix,ubilityofthefunctionalizedCNTsandthemementalThepolymermatrixPVAis95%hydrolyzedwithanaveragemolecularweight60,tiwallcarbonnanotubes(MWNTs)producedbychemicalvapordepositionhaveaspecificdiameterof10–⁎.:+8626.E-mailaddress:phyzhaobo@().0167-577X/$–seefrontmatter©:10.1016/.2008.07.03730nmandthepurityisgreaterthan95%.TheCNTswerefirstlytreatedwithmixedacidandthensodiumhydroxide(NaOH).Inatypicalexperiment,1gofpristineCNTwasaddedto60mlofmixedacid(HNO3:H2SO4H2SO4=3:1)inaround-bottomedflask,andrefluxedat90°entrifugation,thelectionwasdriedanddesignatedasCNT-COOH.0.5gofCNT-COOHwasaddedin10mol/lNaOHsolutionandstirredat90°turewasthenfilteredthroughapolyvinylidenefluoride(PVDF)filterwiththeporesizeof1.2μ,thecollectionwasdriedundervacuumat60°/icalprocedure,turewasultrasonicatedfor15minandstirredat90°rtostudytheeffectsofCNTsonthehomogenizationofPVA/CNTcomposites,someoftheas-preparedPVA/CNTsolutionswerepouredintoaTeflonmould,wherethewaterevaporatedtoleaveafree-standingfiancedtensilestrengththreadswereobtainedbycoatingthepolypropylenethreadswiththePVA/othecoating,thepolyprop,ngElectronMicroscope(SEM,FEISIRION200)measurementswereconductedtoinvestigatethemorphologyofthePVA/etestswerecarriedoutonauniversalmaterialtestingsystem(CMT6404).sanddiscussionToachievefullreinforcingpotentialofCNTs,theymustbewelubility

al./MaterialsLetters62(2008)4380–tographsoftheCNT-COOH(a)andCNT-COONa(b)ementswerecarriedoutbydissolving0.002gofpristineCNT,CNT-COOHandCNT-COONain10mlofdeionizedwater,,tographsoftheCNT-COOH(sametothepristineCNT)stineCNTandCNT-COOHsolutionsareeasilyprecipitated,spersityindex(PDI)ral,thesmallerthePDIvalue,thebetterthesolution'sdispersion[10].uesofthepristineCNT,CNT-COOHandCNT-COONaare0.477,0.405and0.249,tosay,facesofCNTspossessnegativecharge,cturemorphologiesofPVA/CNTcompositesfilmninFig.2(a),therearemanyagglomeratesandbundlesinthecompositefilmswithCNT-COOH,r,theCNT-COONadispersesTsarepulledoutofthepolymer,whichindicatesthattheycicalstress–straincurvesforthethreadcoatedwithPVA,PVA/CNT-COOHandPVA/sshowthatthemechanicalpropertiesofthethreadcoatedwithPVA/CNT-COOH,andPVA/CNT-COONaaresignifiedtotheoriginalpolypropylenethread,tensilestrengthofthethreadcoatedwithPVA/CNT-COONaincreasesby117%from51MPato124MPa,andthetoughnessincreaseby560%esultsmaybeexplainedbytheeffectiveload–ldispersedCNT-COONabondstronglywithPVAmatrix,nthethreadcoatedwithPVA/CNT-COOH,nanotubestendtoagglomerate,gesoffracturesurfaceofPVA/CNTcompositefilmswithCNT-COOH(a)andCNT-COONa(b).Theinsetisthemagnifi,sionsCoatedthePVA/CNTcompositesonpolypropylenethread,olubleMWNTswereusedtogethomogeneousPVA/Tsweretreatedfilstress–straincurvesfororiginalpolypropylene(a)andpolypropylenecoatedwithPVA(b),PVA/CNT-COOH(c)andPVA/CNT-COONa(d).

al./MaterialsLetters62(2008)4380–4382Table1TensilepropertiesofthepolypropylenethreadcoatedwithPVA/CNTssolutionsSampleYoung'smodulusTensilestrengthToughness(MPa)(MPa)(MPa)Originalpolypropylene223516.27PVA2646717.38PVA/CNT-COOH2836511.55PVA/CNT-COONa48412441.32MWNTsinPVAsolutionandastronginterfacialbondingwiththematrixareresponseforthesignifiledgementsThisworkissupportedbyShanghaiScienceandTechnologyGrantNo:nces[1]1991;354:56–8.[2]LourieO,ysLett1998;73(24):3527–9.[3]TreacyMMJ,EbbesenTW,1996;381:678–80.[4]QianD,DickeyEC,AndrewsR,ysLett2000;76(20):2868–70.[5]SandlerJ,ShafferMSP,PrasseT,BauhoferW,SchulteK,r1999;40:5967–71.[6]FlahautE,PeigneyA,LaurentCh,MarliereCh,ChastelF,ter2000;48(14):3803–12.[7]PeigneyA,FlahautE,LaurentCh,ChastelF,ysLett2002;352:20–5.[8]XuCL,WeiBQ,MaRZ,LiangJ,MaXK,1999;37:855–8.[9]DaltonAB,CollinsS,MunozE,RazalJM,EbronVH,FerrarisJP,2003;423:703.[10]BuchhammerHM,MendeM,dsSurfA:PhysicochemEngAsp2003;218:151–9.