PET_PTT共聚酯的热及热氧降解行为

251Vol.25,No.120091POLYMERMATERIALSSCIENCEANDENGINEERINGJan.2009PETPTT方王平,杨胜林,李光,江建明(,201620):由TGA测定了通过先酯化再缩聚方法合成的PETPTT共聚酯(以PET,PTT作对照)在一定升温速率下氮气及空气气氛中的热失重行为采用Friedman和Chang方法研究了样品的降解动力学研究表明,在氮气和空气气氛中PETPTT共聚酯的热稳定性都介于PET和PTT之间,且随着PET链段单元含量的增加,共聚酯的热稳定性提高气氛对聚合物降解行为的影响很大,在空气中PETPTT共聚酯的起始分解温度下降了近50,且在空气气氛中存在两个降解阶段,空气中的氧在降解的第一阶段起了催化剂的作用:PETPTT;;:O631.2+2:A:10007555(2009)01006304:20071113;:,,Email:[e-mail],PET,PBTPTT,PETPBTPTT,;PBTPET(PET/PBT)(PETPBT)PET[1,2]Wei[3]PETPTT,,FriedmanChang,11.1(PTA)(PDO+EG),PETPTT[4],PETALDRICH,PTT,PETPTT1.2/(11),25(BrukerAdvance400),Yamadera[5]PETPTT1.3(TG)NETZSCHTG2091mg,,10K/min,50mL/minTG,Arrhenius:d/dt=Z(1-)nexp(-E/RT)(1):!!!t;d/dt!!!;Z!!!;n!!!;E!!!;R!!!,8314J/(mol∀K);T!!![6]Friedman:ln(Z)=ln(d/dt)-nln(1-)+E/(RT)(2)(1),ln(d/dt)ln(1-)1/T,-E/RE/(nR),(1)Z[6]Chang:ln[(d/dt)/(1-)n]=lnZ-E/(RT)(3)n,ln[(d/dt)/(1-)n]1/T,-E/Rln(Z)[6]22.1PETPTT,Fig.1Fig.1ThreepossiblesequencesinPETPTTcopolyestersTab.1ThecharacterizationofvariousPETPTTcopolyesters(preparedwithvaryingthefeedratioofdiolmonomersinthepolymerization)Sample[](dL/g)PTTincopolyester(mol%)LPETLPTTBPETPTT150.701511.351.720.670PETPTT300.72306.311.760.727PETPTT850.70852.1812.770.537TheintrinsicviscosityofPETandPTThomopolymersis070dL/gand090dL/g,respectively[4]1HNMR13CNMR,Tab.1B,B=1,,B1,;B=0,;B=2,PETPTTB1,PETPTT,,,PDO,PDO15%30%,LPTT2.2Fig.2PETPTTPETPTT(Fig.2(a))(Fig.2(b)),50mL/min,10K/minFig.2(a),,PTT(Tdi),(Tmax),PETPTTPETPTT(Tab.2),PET,Fig.2DynamicTGcurvesofPET,PTTandPETPTTcopolyesters,attheheatingrateof10K/mininnitrogen(a)andair(b)642009,PET,PTTPETPTT,,Fig.2(b)Du[7]PET,,PETPTT50,,Tab.2KineticparametersofthermaldegradationforPET,PTTandPETPTTcopolyestersundernitrogenandairattheheatingrateof10K/minSampleTdi/Tmax1()FriedmanEnln(Z)r1r2ChangEnln(Z)rInnitrogenPET417.0/44.1297#22.0490.99970.9998346#12.5580.9999PETPTT15408.0/439.4288#21.9480.99940.9993301#22.4510.9997PETPTT30395.1/427.3324#33.2560.99960.9997326#23.7560.9998PETPTT85386.7/409.7353#22.1620.99970.9995375#22.6660.9999PTT382.2/405.2327#11.7580.99930.9999356#12.2630.9999InairPET364.3/420.288#10.7130.99960.9999167#21.2280.9991PETPTT15352.0/415.1126#21.0200.99940.9990160#31.5270.9979PETPTT30343.2/405.5143#31.4240.99840.9999217#11.9380.9999PETPTT85337.3/389.5166#21.1300.99940.9995260#11.6480.9999PTT327.7/385.5154#21.0270.99900.9994234#31.5430.9991,,Tab.2,PETPTT15,,,PET,PTTFig.3(a)FriedmanPlotsofln(d/dt)orln(1-)vs.1/TfordirectcalculationofEorn,(b)Changplotofln[(d/dt)/(1-)n]vs.1/TforthethermaldegradationofPET,PTTandPETPTTcopolyestersattheheatingrateof10K/mininnitrogen2.3FriedmanChangPETPTTPETPTTFig.3(2)FriedmanChang,,104/TTab.2Friedman,,Tab.2,09980,,E,E()n651:PETPTT(1-),n,,En,FriedmanChangTdTmax,ETdTmax,,,,(),50,PETPTTE,n,,,,,3PETPTTPETPTT,PET,,50,,:[1]JUEZF,CHENFL.PBT/PETconjugatedfibers:meltspinning,fiberproperties,andthermalbonding[J].PolymerEngineeringandScience,2004,44(2):331344.[2]LYOOWS,LEESG,HAWS,etal.Ahighperformanceliquidchromatographymethodtodeterminemonomerreactivityratiosincopolycondensationofbis(4hydroxybutyl)terephthalateandbis(2hydroxyethyl)terephthalate[J].PolymerTesting,2000,19:299309.[3]WEIGF,HUADB,GULXJ.Thermalstabilityofpoly(ethylenecotrimethyleneterephthalate)s[J].J.Appl.Polym.Sci.,2006,101:33303335.[4].PTT[D].:,2006:3745.[5]REIZOY,MASAOM.Thedeterminationofrandomnessincopolyestersbyhighresolutionnuclearmagneticresonance[J].J.Polym.Sci.PartA:Polym.Chem.,1967,(5):22592268.[6]LIXG,HUANGMR,GUANGH,etal.Thermaldecompositionkineticsofliquidcrystallinepoxybenzoate/ethyleneterephthalate/thirdmonomerterpolymer[J].PolymerDegradationandStability,1999,65:463472.[7]DUXH,ZHAOCS,WANGYZ,etal.Thermaloxidativedegradationbehavioursofflameretardantthermotropicliquidcrystalcopolyester/PETblends[J].MaterialsChemistryandPhysics,2006,98:172177.BehaviousThermalandThermalOxidativeDegradationofPETPTTCopolyestersFANGWangping,YANGShenglin,LIGuang,JIANGJianming(CollegeofMaterialScienceandEngineering,DonghuaUniversity,Shanghai201620,China)ABSTRACT:Thermalgravitationanalysesofaseriesofpoly(ethylenecotrimethyleneterephthalate)(PETPTT)copolyesterspreparedbydirectesterificationandasequentialpolycondensationwerecarriedoutunderacertainheatingrateinnitrogenandair,theresultswerealsocomparedwiththoseofPETandPTThomopolymers.FriedmanandChangtechniqueswereusedtoanalyzedynamicthermogravimetrickineticsofallthesamples.Itshowsthatunderbothnitrogenandairatmosphere,thethermalstabilityofPETPTTcopolyestersisintervenientbetweenPETandPTT,andincreaseswithanincreasingcontentofPETunits.Forallsamplestheonsetdegradationtemperaturedecreasesabout50inaircomparedtothatinnitrogenandshowstwoweightlossstages.Fromtheanalysisofdecompositionkinetic,itcanbededucedthattheoxygeninairactsascatalyzerinthefirstweightlossstage,resultinginthedecreaseofonsetdegradationtemperatureaswellasthelowerdegradationactivationenergyandrate.Keywords:poly(ethylenecotrimethyleneterephthalat);thermaldegradation;thermaloxidativedegradation662009