DSC法测定聚乙烯结晶度的研究

DSC张　乾,解云川,范晓东(,710072)　:DSC(PE)。X(WAXD)DSCPE,DSC。DSC(MDSC)PE,,PE。PE,DSC,。　　:;;:TQ330.7+2　　:B　　:1001-9278(2002)09-0073-04　　PE。,、(DSC)、、、X。DSCPE,,DSCPE。(LDPE),(Tg)(≤-60℃)[1],,。Gray[2,3](Totalenthalpymethod)PE(1)。1　[4]Fig.1　Figureoftotalenthalpymethod1,T2,H-H1T1～T2,ΔHf100%,Xc=(H-H1)/ΔHf。,X[4]。,DSC:2002-05-27:“”(:6100521)。,,。,(T1、T2)DSC,,DSC(2)。,,DSC。2　Fig.2　ExperimentaltestofcrystallinityandenthalpyDSC3[5,6]。PE,DSC,0,DSCPE。PE(Cp)。(Cpc)(Cpa)[6]。,,。3,[7]。,T1,16　9　　　Vol.16,No.920029CHINAPLASTICSSep.,2002—　—　---—-·-—DSC3　Fig.3　ActualbaselineagainstmeltingprocessDSC,、。T1,,DSC,,,()。T2,,DSC。,DSCT1～T2。DSCDSC。,3。100%,3DSC。,T1T2DSC。1,。(HDPE),,,DSC。,。1　20℃Tab.1　Comparisonofcrystallinityat20℃testedbytotalenthalpymethodandexperiment(20)LLDPE-DFDA7042LDPE-2102TN00HDPE-DFDA60980.40960.40760.40140.40260.60840.52930.01140.02100.00900.00920.02740.05850.00250.00470.00200.00210.00610.0131//%0.62021.15300.50070.50911.00602.4730DSCPE,PE。,T1。DSC(MDSC),PE,PE,。1　1.1　LDPE,2102TN00,;LLDPE,DFDA7042,;HDPE,DFDA6098,。1.2　(a)LDPE:2102TN00　Xc=37%　(b)LLDPE:FFDA7042　Xc=38%(c)HDPE:DFDA6098　Xc=59%4　PEWAXDFig.4　WAXDdiffractioncurvesandcrystallinityofthethreePEDSC,TATMDSC2910(MDSC),,,。PE5.0mg～6.0mg,DSC-50℃,10℃/min,170℃。X(WAXD),PHILIPSX,,Cu,40kV,40mA,2.5°/min,,2θ=5～50°,DS=1°,RS=0.1mm,SS=0.1mm,。2　WAXDX4。　·74　　　·DSC　PE(20℃)LDPE37%、LLDPE38%、HDPE59%。1DSC20℃,LDPE。[4]。5PEDSC。LDPELLDPEHDPE,。LDPE,LDPEHDPE。LDPEDSC20℃,HDPE70℃。——HDPE:DFDA6098　---—LLDPE:DFDA7042-·-—LDPE:2102TN005　PEDSCFig.5　DSCcurvesofthethreePE2PET1,PE3,T-1#、T-2#、T-3#。PET1,LDPELLDPE,-30℃50℃10%,HDPE3%。2　PET1Tab.2　CrystallinityofPEagainstT1T1/℃LDPE(2120TN00)LLDPE(DFDA7042)HDPE(DFDA6098)T-1#T-2#T-3#T-1#T-2#T-3#T-1#T-2#T-3#-300.44270.43810.44650.47480.47630.45670.57930.62560.5841-200.42950.43010.43330346150.46910.44610.57790.62160.5853-100.42010.42200.42280.45420.46400.44080.57930.62270.588900.41310.41210.41500.44600.45940.43200.58140.62450.5940100.40670.40680.40770.44420.45440.43250.58400.62640.5953200.40090.39530.39790.44240.45240.43170.58160.61980.5849300.38180.38950.38070.41840.43150.42050.57830.61540.5861400.34050.35490.34500.35210.37200.36600.57100.60660.5784500.30060.30050.29210.34300.35420.34760.55920.59430.5663V.B.F.Mathot,DSCPE-60～120℃,-60～130℃。-60℃40%[8],。PE,。——LDPE:2102TN00　---—LLDPE:DFDA7042-·-—HDPE:DFDA6098:　　LDPE:-40～0℃———1.536+1.112×10-2T(R2=0.9999)25～50℃———1.181+2.123×10-2T(R2=0.9964)　　LLDPE:-40～0℃———1.607+1.002×10-2T(R2=0.9999)25～50℃———1.480+1.360×10-2T(R2=0.9998)　　HDPE:-40～0℃———1.427+5.890×10-3T(R2=0.9962)25～50℃———1.355+1.098×10-2T(R2=0.9987)T———　R2———6　PEFig.6　HeatcapacitycurvesofPEPE[9],MDSC。,,PE-(Cp-T)(10-3)[10,11]。,。PE,-50℃,5℃/min170℃,±1℃/60s,-40℃～50℃,,6。6,,。-40～0℃,HDPE10-3,,PE。LDPELLDPE10-2,HDPE。25～50℃,PE,HDPE10-2,。LDPE,T1HDPE[8]。LDPE,　20029　　　·75　　　·　,。,T1,PE(Tg)T1。PE,PE,,ASTM:E793—95。,,PE,,(),PE。3　(1)DSCPE,T1(T1Tg),。(2)PE,,PE。(3)PE(Cp),PE。PE。(4)DSCPE。:[1]　,,.[M].:,1990.[2]　GRAYAP.ThermochimicaActa,1970,1:563.[3]　RICHARDSONMJ.PlasticsandRubber:MaterialandAp-plications,1976,(1):162.[4]　BLUNDELLDJ,BECKETTDR,WILLCOCKSPH.Rou-tinecrystallinitymeasurementsofpolymersbyDSC[J].Poly-mer,1981,22:704～707.[5]　.[M].:,1987.[6]　WUNDERLICHB.ThermalAnalysis[M].NewYork.Aca-demicPress.1990.[7]　MATHOTVBF.Temperaturedependenceofsomether-al-dynamicfunctionsforamorphousandsemi-crystallinepoly-mers[J].Polymer,1984,25:579～599.[8]　MATHOTVBF,PIJPERSMFT.JApplPolymSci,1990,39:979～994.[9]　DANIELSF,ALBERTYRA.[M].:,1984.[10]　WUNDERLICHB,JINY,BOLLERA.Mathematicalde-scriptionofdifferetialscanningcalorimetrybasedonperiodictemperaturemodulation[J].ThermochimicaActa,1994,238:277～293.[11]　CLARKES,FOLLANDP,MATISONSJ.ThermochimicaActa,2000,351:29～31.DeterminationofPolyethyleneCrystallinitybyDSCZHANGQian,XIEYun-chuan,FANXiao-dong(ChemicalEngineeringDepartmentofNorthwesternPolytechnicalUniversity,Xi'an710072,China)Abstract:TheoryandmeansofthedeterminationofcrystallinityofpolyethylenebyDSCwasstudied.BycomparingthecrystallinitydataofWAXDandconventionalDSC,therationalityofdeterminationofpolymer'scrystallinitybyDSCwasdiscussed.Itwasverifiedthatthereexistssmallcrystal'smeltingunderlowertemperaturewhichcaninflu-encethecrystallinity'sexperimentalvalueconsiderably.Theresultcanalsobeconfirmedbymeasuringtheheatcapaci-ty(Cp)ofrelatedsamplesusingmodulatedDSC(MDSC).ItwaspointedoutthatasPE'scrystallinityvalueswerecloselyrelatedtotheirenvironmentaltemperature,itwasveryimportanttoselecttherangeoftemperatureofbaselineonDSCcurveswhenconductingthemeasurementonPE'scrystallinity.Keywords:polyethylene;crystallinity;MDSC　　20021,《》,,;,,。《》2002918　·76　　　·DSC