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分子量及其分布对聚羧酸减水剂吸附行为的影响

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第39卷第1期2011年1月硅酸盐学报JoURNALOFV01.39,No.1January,2011T眦CHⅡVESECERA^缸CSOCⅢTY分子量及其分布对聚羧酸减水剂吸附行为的影响李顺,余其俊,韦江雄,季亚军(华南理工大学材料科学与工程学院,特种功能材料教育部重点实验室,广州510640)摘要:从分子量及其分布角度研究聚羧酸系减水剂在水泥颗粒表面的吸附行为,分析了聚羧酸减水剂的吸附行为对其分散性、保坍性的影响。结果表明:平均分子量较高的减水剂在水泥表面的吸附量较高.减水剂分子中的高分子量部分优先吸附在水泥颗粒表面;对于同一减水剂,随其在水泥表面的吸附量增加,浆体的流动度增加,两者之间呈正相关性;而对于不同减水剂,吸附量与流动度之间的相关性较差。聚羧酸系减水剂在水泥、粉煤灰、矿渣等胶凝材料表面吸附行为的对比分析,有利于指导聚羧酸减水剂的分子设计,从而提高其与复合水泥之间的相容性。聚羧酸减水剂专业制造商三瑞企业www.sunrisechem.com.cn

关键词:聚羧酸减水剂;分子量及其分布:吸附:分散性中图分类号:TQ172文章标志码:A文章编号:0454-5648(2011)0I--0080-07EffectsofMolecularMassandItsDistributiononAdsorptionBehaviorofPolycarboxylateWaterReducersL/Shun,YUQijun,IVEIJiangxiong,JIYajunMaterialsofMinistryofEducation,SchoolofMaterialsScienceand(KeyLaboratoryofSpeciallyEngineering,SouthChinaUniversityofTechnology,Guangzhou510640,China)FunctionalAbstract:Theadsorptionbehaviorofpolycarboxylatewaterreducers(PCs)onthesurfaceofcementparticleWaSinvestigatedviatherespectofmolecularmassanditsdistribution.111eeffectofadsorptionbehaviorofPCsaonthedispersibilityanddispersionretentiononcapabilityWaSanalyzed.TheresultsshowthatadsorptionamountofPCswithmentparticleiShigherthanthatofPCswithahigheraveragemolecularmassathesurfaceofce-molecularmaSsadsorbpreferen-tiallyonthesurfaceofcementparticle.ForthesamePCs,thefluidityofcementpasteincreasedwithincreasingtheadsorptionamountonthesurfaceofcementparticles,andthefluidityofcementpastewascorrelatedtoadsorptionamountofPCs.Forthedif-lowerhi【ghtoolecularmass,ThePCsfractionswithferentPCs.however,thecorrelationwaspoor.ThestudiesonthedifferentadsorptionbehaviorsofPCsstructureonthesurfaceofashandgroundgranulatedblast.furnaceslag(GGBFS)couldfavorthedesignofmolecularcompatibilitybetweenPCsandcompositeconent.andthecement,flyimprovementoftheKeywords:polyearboxylatewaterreducer;molecularmassanditsdistribution;adsorption;dispersibilitySuperplasticizershavebecomeofthecomponentsstericonecanhindranceeffect.[2-91Yamadaet口,.【lo】exploredtheonusedgreatlyimprovethequalityofconcreteandpromotethedevelopmentofcon-SOuseinconcretefar.TheirthepropertiesofthePCs.Lieta1.I“JdiscussedtheinfluenceofpolyethyleneOX.effectofchemicalstructurecretetechnology.Polycarboxylatewaterofthe1110streducers(PCs)havebeenide(PE01chainontheperformanceofthePCs.Choettheeffectofsyntheticconditionsonasoneimportantsuperplasticizersa1.t1纠investigatedinvestigatedduringthepastetwodecades.Consequently,thePCshavedevelopedsincethe1990sduetotheIx)ten-fiallydesignablemolecularstructure.L1JComparedtothethedispersibilityofthePCs.Planketa1.1‘’1训analyzedthedispersibilityandadsorptionbehaviorofthePCSwitIlrespecttomolecularstructure.Someworkalsoexploredonconventionallentwaterstabilityat收稿日期:asuperplasticizers,thePCspossesscapabilityandaallexcel—theadsorptioncharacteristicsofthePCsthecementreducingdispersionretentionlowcontent,whichmainlyresultsfromthe修改稿收到日期:2010--10-09。componentmineralsandattemptedtocontroltheadsorp—tionofthePCsbyadjustingtheconcentrationofsulfate2010-06-06。Receiveddate:2010-06-06.Approveddate:2010-10-09.基金项目:国家。973计划”(2009CB623104),华南理工大学自然科学青年基金(E5090950)资助项目.第一作者:李顺(1977—),男,博士。通信作者:余其俊(1963—),男,博士,教授。Firstauthor:LIShun(1977-),male,Ph.D..E-rail:lislI16@163.comCorrespondentauthar:YUQij岫(1963-),male,l'kD.,professor.E-marl:concyuq国@sem.cdu.cn第39卷第1期ioninaqueousphase.L1卜1thePCsisbasedon7J李顺等:分子量及其分布对聚羧酸减水剂吸附行为的影响Actually,thedispersibilityofon・8l・fromShaoguanSteelCo.。China.黾blelshowstheirtheadsorptionthesurfaceofce.mentparticles.TheadsorptionbehaviorofthePCsiscorrelatedto也emolecularstrucuture.Thispaperwastoinvestigatetheeffectsofmolecularweightanditsdistributionontheadsorptionbehaviorofchemicalcompositionandphysicalproperties.FigurelshowsthemolecularstructureofthePCsastheserializa-tionproductsofV-lscocretefromSIKACo..China.ForPC.M,PC—E,PC.HEandPC.R,thedegreeofpolymeri—zation(DP)ofpolyethyl@ileoxide(PEO)chainare6,9,16and60.respectively.1.2thePCsonthesurfaceofcementitiousmaterials.11.1MeasurementInfrared(IR)spectrumaExperimentalproceduresMaterialsGrade42.5Portland1.2.1ThePCsweredriedandmixedwithsmallamountofpotassiumbromide.acement(typeII)wasslag(GGBFS)andThesuppliedbyflyashweremixturewasthenmadeintoatabletforthemeas-Co.,YuexiuCementPlantinurementsinVector33IRGuangzhou,China.Groundspectrometer(Brukergranulatedblast-furnaceGermany).TableIChemicalcompositionandphysicalpropertiesofcementitiousmaterialsCementGGBFSFlyash21.2031.1452.425.4019.3330.315.031.034.8964.8434.242.621.4511.75O.911.020.600.530.431.031.063140294037642641018.2312.7321.200.015.752530rfun.upperdiameterof36nnnandabottomdiameterofaccordingtotheCH2--÷1-叶cH:一{七6:o60mm).Theprocesseswere1.2.4performedChinesestandardGB/T8077—-2000.o-{CHzCHzO扣,R=Horca,Fig.1MarshtimeofcementpasteThecementpastewasalsousedforthemeasurementofMarshtime.ThenozzlediameterofMarshconeis8mill.111eprocedurewaswasasfollows:11theMarsh2)500gconeattachedintothetoastand;ofcementpastewaspouredconewhenathenozzlewasclosed:3)thetimewasrecordedbyGeneralizedmolecularstructureofPCs1.2.2GelpermeationfromchromatographyTheaveragewhenthenozzlewasopened;钔thefor200mLofcementpastetoflowwasrecordedflowtimewasdefinedastheMarshtime.stop-watch1.2.5AdsorptionamountofPCsPCsonrecorded.毗durationmolecularmassanddistributionofthePCsweredeter-minedgelpermeationachromatography(GPC)Theadsorptionmeasurementsamountofthethesurfaceofcemenfitiousmateri-usingWaters515chromatographicap.paratusequippedwithfourcolumnsUltrahydrogel120,250,500andl000,aswellasadetector(Waters2410).als(cement。flyashandGGBFS)wasmeasuredwithatotalorganiccarbon(TOC)analyser.20gofaqueoussolutionwitllvariousThetemperaturesolutionasanamountsofthePCsandaofcolumnwaskeptat40℃.Thesam.pieswereanalyzedusinga0.1mol/LofNa2S04aqueouseluant.atacementitiousmaterialsweremixedbymagneticof10gofstirrerflowrateof0.6rnL/min.Thefor5min.Then。theupperwasfilledintoasuspensionacementpastemono-dispersivepolyethyleneglycolswithvariousmo.1ecularmasseswereused勰calibrationstandards.Forthealkalineporesolution,thepHwasadjustedto2..3bvaddingnitricacidtoimprovethestabilitybeforethecentrifugeat4200r/minfor30milland0.45pmmem-theresultantSOIutionwasfilteredbybraneusingavacuumpump.TheconcentrationofthePCsremainedintheresultantsolutionwasmeasuredbvToC.TheadsorptioncementifiOUSmaterialsamountcanofPCsonthesurfaceofonmeasurement.1.2.3apreparedat20℃.ThePCswereaddedintowateratasolidcontentrangingfrom0.15%to0.4%.ThesealedinaFluid时ofcementpastewater-cementratioof0.35wasAcementpastewithdifferencebetweenthebeamountscalculatedbasedtheofPCsinaqueousphasebeforeandaftermixing.containerforspecimenofcementpastewas5。30and60minbeforethefluidityofcementpaste22.12.1.1ResultsanddiscussioncharaeterizationofPCsIganalysisFigure2showstheIRspectraofmeasurement,respectively.ThewasmeasuredusiIlgaminislumpcone(aheightof60・82・硅酸盐学报2011年mN“40003500300025002000l5001000500Wavenumber/era一1Fig.2IRspectraofPCsfourPCswithvariousfunctions.Thewiderabsorptionpeaksvaryingfrom3400to3500cm-1areduetothestretchingVibrationoftheo_Hbond.Thecharacteristicabsorptionpeaksofthepolyethyleneoxidegroup(PEO,一CH2CH20’矿)aredetectedatabout2880,l457,l353,951and848crn-1,includingthes仃etchingvibra-tionofC_Hat2880cm-‘anditsflexualvibrationatl457and1351cm-1:thestretchingvibrationofC-OandC—cat951and848cm-1,respectively.Thoseabsorptionpeaksat125.2and1106cm-1areattributedtothestretchingvibrationof∞illmeC—孓Cstructure.whicharethetypicalabsorptionpeaksoftheether.Thestretchingvi.brationofC—OintheesterbondCallbeobservedatl727cm-1.Thecharacteristicabsorptionpeaksat1573cm-1resultsfromthestretchingvibrationofthe—COOgroup.ItisindicatedthatthefollowinggroupsexistinthemolecularstructureofthePCs,suchasthehydroxy,carboxyl。etherli咄esterbond,andpolyethyleneoxidegroup.2.1.2GPCanalysisFigure3andT{出le2showtheGPCmeasurementresultsoffourdifferentPCs.InFig.3.themolecularmassdistributionofthePC—HE.whichcanbeshownbyPDI。isthewidest.In1'able2.themassav.eragemolecularlIlaSS(』I磊)andnumberaveragemolecu-larmass(^厶)ofthePC—HEbotharethelowestamongthefourPCs.TheseresultsindicatethatthePC.HEiSmainlymadeoflightmolecules.ComparedtootherPCs.thePC.Rhasthehighest%and坛andthelowestPDI,indicatingthatthePC..Rismainlymadeofheavymole—.cules;andthedifferentvalueofM.-M。ofthePC.Rislarger,illustratingthatthereareexcessivehighmolecularmoleculesinPC.R.Also.comparedwimthePGM,themolecularmassandPDIofthePC.Earesmaller,showingthattherearemoresmallermoleculesinPC.E.2.2FluidityofcementpasteFigure4showsthefluidityofcementpasteasafimc-tionofsoliddosageofPCs.Thefluidityincreasedwithincreasingthedosage,andtheincrementvariedwiththe。篆詈SliceIg%(a)PC-ES兽罩奢零奇互SliceIg%(b)PC-M葛ISliceIg坂(c)PC-R摹宙焉善Sliceig帆(c)PC-HEFig.3Molecularm88sdistributionofPCsS喾耄S兰罩誊第39卷第l期李顺等:分子量及其分布对聚羧酸减水剂吸附行为的影响・83・Table2AveragemolecularmassandPDIofPCstypeofPCs.ThefluidityofcementpastewiththePC.Ewaslower,andthecorrespondingvalueatthesaturationpointof0.3%was220mm.ComparedtothePC.E.thefluidityofcementpastewiththePC.RwasobviouslyimprovedandthemaximumvalRereachedabout255mmatasaturationpointof0.35%.Thefluiditiesofthece.mentpasteswiththePC.MandPC.HEincreasedandreached290and300ram,respectively,whichindicatesttlattherewasnoobvioussaturationpointat0.4%.Theresultsindicatethattheorderoffluidity(dispersibility,fromlargetosmall)forfourPCsusedcouldbePC.HE.PC—M,PC.&PC—E.ThefluidityofcementpastewiththePC.Mincreasedatthedosageof0.4%fortheelapsedtimeof60min.TllisillustratesthatthePC.Mhasanexcellentdispersionre—tentioncapability.However,thePC—Rexhibitedapoordispersionstability,andthefluidityofcementpastewiththePC.Rdecreasedfor60min.ThePC.EandPC.HEhadthesimilardispersionstability,andtherewasnoflu-iditylossatthedosageof0.26%and0.28%.respectively.Consequently,theresultsshowthattheorderofdisper-sionstability(fromlargetosmalllforfourPCsusedcouldbePC.M.PC.E,PC—HE。PC.R.2.3MarshtimeofcementpasteTheMarshtimeiscorrelatedtothefluidityofcementpaste.TheMarshtimeofcememtpasteasaBinghamfluidisdirectlycorrelatedwiththetheologicalparame—terssuchasyieldstressandplasticviscosity,t1驯Forthecementpastewithawaterreducer,theYieldstressbe-comesrathersmallandthevalueofMarshtimeismoresensitivetotheplasticviscosity.InFig.5,theMarshtimeofcementpastewiththePC.-MandPC..HEat5millde—-creasedwithincreasingthedosagefrom0.15%to0.4%.illustratingthattheydidnotreachthesaturationpointat0.4%.ForthePC.EandPC.Rused.theirMarshtimedecreasedtoaminimumvalueatthedosageof0.3%.TheresultssuggestthatthesaturationpointofthesamePCsdeterminedbyMarshtimeandfluiditybesometimesdifferent.TheresultsinFig.5showthattheorder(fromlargetosmall)of5minMarshtimeofcementpastewiththedosageof0.15%couldbePC.M,PC.E.PC.R。PC.脏andthattheorderoftheshortesttime(correspondingtothesaturationpoint)ofcementpastecouldbePC.E.PC.R,PC.HE,PC-M,whichindicatesthatthedosagehasagreateffectontheMarshtimeofcementpastewithPC.M.However,the60millMarshtimeofcementpaste董害羞Dosage/%(a)PC—EDosage/%(b)PC-M量耋星Dosage/%(c)PC-R砌O船O拍O,营pMO笼O0.150.200.250.300.350.40Dosage/%(d)PC-HEFig.4FluidityofcementpastewithdifferentcontentsofPCs・84・硅酸盐学报2011笠Dosage/%(a)PC-EDosage/%(bJF,lC-MDosage/%(c)PC-R铒∞弘记嚣M加0.150.200.250.300.350.40Dosage/%(d)PC-HEMarshtimeofcementpastewithdifferentcontentsofPCswithPC—Mchangedslightlywithincreasingthedosage.111iSmightbecorrelatedtotherhe0109icalparametersofcementpaste.Also,comparedtothefluidityresults,itcouldbeindicatedthatthedecreaseofMarshtimecouldnotal-waysleadtotheincreaseofthefluidityofcementpaste.2.4AdsorptionofPCsFigure6showstheadsorptioniSOtherlTiSofdifferentPCsonthesurfaceofcementparticles.TheadsorptionamountofPC..EandPC.-Mincreasedgraduallyandthenreachedaconstantvaluewithincreasingthedosage.TheseadsorptionisothermsshowatypicalLangmuircurve.ForthePC—HEandPC.R.theycouldnotobtainanequilibriumadsorptionattheamountsdosageof0.8%.nlemaxi-mumadsorptionofPC..EandPC..MwerelargerthanthoseofPC.HEandPC.R.1’able2showsthatthe眠valuesofPC.RandPC.HEwerethehighestandlowest,respectively.Basedontheadsorptionresults,thePCswithtoohighortoolow蝙couldgivetheslightadsorptiononthesurfaceofcementparticles.乞曾著=i墨蕾薯Dosage/*/,Fig.6AdsorptionofPCs011thesalivateofcementInFig.7.thefluidityofcementpasteincreasedwitllincreasingtheadsorptionamountofthePCsonthesur-faceofcementparticles.EachPCshowedthedifferentvariationregularity.ForthecementpastewiththePC—HE.itexhibitedahigherfluidityataloweradsorptionamount.However,thecementpastewithPC.Mexhibitedahigherfluidityatahigheradsorptionamount.ForthePC.E,thefluidityofcementpastewaslowereVenatahigherad-sorptionamount.ForthesePCsused,thefluiditycouldbecorrelatedtotheadsorptionamount.Forinstance,ahigheradsorptionamountdidnotleadtoahigherfluid-ity.ThiScouldbecloselyrelatedtothesterichindranceeffectofPCsduetothedifferentmolecularstructures.ThePCswithastrongersterichindranceeffectshowsaadsorptioncapability.However,onceitcouldadsorbthesurfaceofcementparticles,itwouldexhibitthedispersibility.Inthecaseofthesamemoleculars仃.uctIlre.thePCsahighermolecularnlaasshowsastrongeradsorp-tothatwithalowermolecuarmass.Tothise仃.ect.themolecularmassdistributionofPCsandafteradsorptiononthesurfaceofcementnotonpoorFig.5strongwithtion,comparedprovebefore第39卷第l期李顺等:分子量及其分布对聚羧酸减水剂吸附行为的影响・85・Adsorptionamount/(mg・g一1)Fig.7Relationshipbetweenadsorptionamountandfluidityparticlesinthesolutionwasevaluated.Figure8showsthatthemolecularmassdistribufionsofPC—RandPC—Minthesolutionshiftedtoalowermolecularmass.corn-paredtotheoriginalPCsSOlution,indicatingthatthosefractionswithahighermolecularmasscouldpreferen-tiallyadsorbonthesurfaceofcementparticles.Intheory,apreferredadsorptionofthehighmolecularmassfrac.tionisexpectedinadilutesystemduetothethermody.namicprocesses.【1”01Inotherwords.theadsorptionofhigherpolymerfractionscouldfavortheincreaseofell-订opy,leadingtothedecreaseinthefreeenergyofad-sorption.【20】Figure9showstheadsorptionisothermsofdifferentPCsonthesurfaceofflyash.ExceptforthePC.E.theSlicelg耽(b)Fig.8MolecularmassdistributionofPCsbeforeandafteradsorptiononthesurfaceofcement2.62.42.2201.81.61.41.21.OO.80.60.4O.2ODosage/%Fig.9AdsorptionofPCsonthesurfaceofflyashothersdidnotobtainanequilibriumadsorptionatados—ageof0.8%.ItWasindicatedthatthePCswithahigher%couldhaveas仃ongeradsorptioncapabilityonthesurfaceofflyash,whichissimilartotheadsorptionregularityofthePCs011thesurfaceofcement.ThePC—I乙gavethestrongestadsorptioncapabilityonthesurfaceofflyashandtheweakestadsorptioncapabilityontheSill'-faceofGGBFS(seeFig.10).Thiscouldbepartlyresultedfromtheirdifferentchemicalandmineralogicalcomposi.tion.【“JThesedifferencesinadsorptioncouldhaveaneffectonthecompatibilitybetweenthePCsandcompos—itecement.Dosage/*/,Fig.10AdsorptionofPC-Ronthesurfaceofdifferentcemen-titiousmaterials3Conclusionsn11ledecreaseofMarshtimeofcementpastedidnotalwayslcadtotheincreaseofthefluidity.2)ForthesamePCs,theadsorptionamountcouldbecorrelatedtothefluidity.ForthedifferentPCs.however,theircorrelationwaspoor.31ThePCswithahigheraveragemolecularmassex.hibitedahighel"adsorptionamount.Inthecaseofthesamemolecularstructure,thehighermolecularmassfractionscouldpreferentiallyadsorbonthesurfaceofcementparticles..86.硅酸盐学报2011年References:fl】KINOSHITAM,YONEZAWAT'YUKIY.Chemicalstructureandperformanceofanewtypehighrangewalerreducingagentforultrahighstrengthconcl'ete[J】.Semento,KonkuritoRunbunshu,1993,47:196__201.【2】OHTAA'SuG“AMAT'TAMAKAYFludizingmechanismandapplicationofPolycarboxylatebasedsuperplasticizers【A]//MALHOTRAVMed.5thCANMET/AClInternationalConferenceonSuperplasti-oizeTsandOtherChemicalAdmixturesinConcrete,Rome。Italy,1997:359-378.【3】YOSHIOKAKSAKAIE,DAIMONM,eta1.Roleofsterichindranceintheperformanceofwater-reducersforconcrete叨.JAmCeramSec,1997,80(10):2667—2672.【4】YAMADAkTAKAHASHIT’MATSUH]SAM.Effectofchemicalstruetureandwatercementr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