2023年全國碩士研究生考試考研英語一試題真題（含答案詳解+作文范文）_第1頁
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1、Adsptionofsurfactantbynanosilicaparticlesincarbonnanotubeswaterdispersions:applicationinacementmatrixOscarA.MendozaReales1WilliamC.PearlJr.2MariaD.M.Paiva2CristianeR.Mira3RomildoDiasToledoFilho11.CivilEngineeringDepartme

2、ntPECCOPPEUniversidadeFederaldoRiodeJaneiroRiodeJaneiro21941972Brazil2.HalliburtonBrazilTechnologyCenterHalliburtonRiodeJaneiro21941907Brazil3.PetrobrasPetrleoBrasileiroS.ARiodeJaneiro21941901BrazilAbstractThiswkstudiesh

3、ownanosilicaparticlesinteractwithacommercialdispersionofnonfunctionalizedcarbonnanotubesrichinsurfactanthowthiscombinationaffectsthepozzolanicactivityofthenanosilicainacementpaste.Thematerialsusedweremultiwalledcarbonnan

4、otubes(MWCNT)dispersedinwaterwithananionicsurfactantasdispersingagentcolloidalsilicananoparticles(NS)dispersedinwaterClassGcement.Cementpasteswithawatertocementratioof0.45additionsofMWCNTNSupto0.50%bymassofcementwereprod

5、ucedintwostepsthedispersionsofnanoparticleswerecombinedwiththemixingwaterusinganultrasonictipprocessthenthecementwasaddedhmixeduntilahomogeneouspastewasobtained.Isothermalcalimetryresultsshowedthatwhenthepasteswereblende

6、donlywithMWCNTthesurfactantpresentinthedispersionactedasaretardingagentdelayingtheheatreleaseofthehydrationreactionwhilstwhenthepasteswereblendedwithNSMWCNTthisretardationeffectwasminimized.Transmissionelectronmicroscopy

7、(TEM)thermogravimetricanalyses(TGA)resultsshowedthatinthefirststepofthemixingtheNSparticlesadsbedtheexcessofsurfactantpresentintheMWCNTdispersionpartiallymaintainingitspozzolanicactivity.iginalityTheretardedhydrationofce

8、mentMWCNTcompositesisstudiedinthiswkanovelapproachtominimizethisretardationusingNSparticlesisproposed.Surfactantsareaneffectivedispersingagentfnonfunctionalizedcarbonnanotubesinwaterbutatthesametimehavethepotentialtowide

9、lyretardthehydrationofcementwhenspecifictypesamountsareused.IftheMWCNTdispersionrichinsurfactantismixedwithcementtheexcessofsurfactantwilladsbontothesurfaceoftheanhydrousgrainskeepingthewatermoleculesawayretardingthehydr

10、ation.Themethodologyproposedconsistsoftheintroductionofanadditionalsurfaceontowhichtheexcessofsurfactantcanadsbpreventingitfromadsbingontothesurfaceofthecementgrains.NSparticleswerechosenfthispurposebecausetheyhaveadualf

11、unctionalityhighsurfaceareafsurfactantadsptionpozzolanicactivity.Keywds:Carbonnanotubesnanosilicasurfactantretardationpozzolaniceffect1Crespondingauth:Tel552139388215Fax552139388221AccdingtotheEDXresultspresentedintable1

12、theXRDpatternpresentedinfigure1NSparticlesarecomposedmainlyofamphoussilica.DLSresultspresentedinfigure2showthattheNShasanaverageparticlesizeof29.0nm(d50)anarrowsizedistribution.NSalsopresentedalossonignition(LOI)of9.0%aT

13、GAwasperfmedtoidentifythesourceofthismasslosstheresultsarepresentedinfigure3.Thetotalmasslossfoundinthethermogravimetric(TG)curveiscompatiblewiththatfoundintheLOItest.Mostofitoccurredunder100Cwithabroadpeakinthederivativ

14、ethermogravimetric(DTG)curveat42Cgoingalmostupto200C.ThisdecompositioneventcanbeassociatedwiththeevapationofadsbedwaterontothesurfaceofthenanoparticlescombinedwithadehydrationofOHgroupspresentinthestructureonthesurfaceof

15、thesilicaasfunctionalgroups.Accdingtothemanufacturerthesefunctionalgroupsweregeneratedonthesurfaceofthenanoparticlestoenhancethestabilityoftheaqueousdispersionovertime.Tab.1ChemicalcompositionsbyEDXspectroscopyofNS%Compo

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