中英文對照外文翻譯(文檔含英文原文和中文翻譯)CrystallizationBehaviorsofLinearandLongChainBranchedPolypropyleneABSTRACT:Thenonisothermalcrystallizationkineticsoflinearandlongchainbranchedpolypropylene(LCBPP)wereinvestigatedbydifferentialscanningcalorimetry(DSC)atvariouscoolingrates.SeveralmethodssuchasAvrami,Ozawa,andJeziornywereappliedtodescribethecrystallizationprocessoflinearPPandLCBPPswithdifferentLCBlevelundernonisothermalconditions.Thevaluesoft1/2,Zc,andF(T)showthatLCBhastheroleofheterogeneousnucleatingagentandacceleratesthecrystallizationprocessofPP.Moreover,theKissingermethodwasusedtoevaluatetheactivationenergyoflinearPPandLCBPPs.TheresultshowsthattheactivationenergyofLCBPPsarehigherthanthatoflinearPP,indicatingthatthepresenceofLCBbafflesthetransferofmacromolecularsegmentsfromPPmelttothecrystalgrowthsurface.Furthermore,thecrystalmorphologyoflinearPPandLCBPPswasobservedthroughpolarizedopticalmicroscopy(POM),andfinespheruliteswereobservedforLCBPPs.Keywords:polypropylene;longchainbranch;nonisothermalcrystallization;kineticINTRODUCTIONIsotacticpolypropylene(iPP)hasmanydesirableandbeneficialphysicalpropertiessuchaslowdensity,highmeltingpoint,andchemicalresistance.Therefore,iPPhasbeenusedwidelyinindustrialandcommercialapplications.However,iPPisalinearpolymer,asaresult,itexhibitslowmeltstrengthandnostrainhardeningbehaviorinthemeltstate,whichlimitsitsuseinapplicationssuchasthermoforming,foaming,andblowmolding.ThemosteffectivemethodtoimprovethemeltstrengthofPPistointroducelongchainbranching(LCB)ontothePPbackbone.TherehasbeenconsiderableinterestintherelationshipsbetweenLCBmoleculararchitectureandrheologicalbehaviorofPPintherecentyears.ThechangeofmoleculararchitecturecanaffectnotonlyrheologicalpropertybutalsocrystallizationpropertyofPP.However,thecrystallizationbehavioroflinearandlongchainbranchedpolypropylene(LCBPP)hasseldombeenstudiedindetail.TherehavemanystudiesonthecrystallizationofgraftedPP.ItiswidelyacceptedthatgraftedPPpartlyactsasanucleatingagentforthematrixandacceleratesthecrystallizationrate.speculatedthatthedifferentcrystallizationbehaviorbetweenPP-g-MAandPPisduetoachaininteraction,suchashydrogenbondingbetweenhydrolyzedmaleicanhydridegroups.ThereisnospecificdefinitionaboutLCB,however,fromrheologicalviewpoint,thelengthnecessaryforabranchtobehaveasalongchainbranchis2Me(Memolecularweightbetweenentanglements).Therefore,themoleculararchitecturesforgratedPPandLCBPPareverydifferent.Asaresult,thecrystallizationbehaviorandcrystalmorphologyofLCBPPwillbedifferentfromlinearPPorgraftedPP.ItcanbeconcludedfromlimitedliteraturesthatLCBPPhashighercrystallizationtemperature,shortercrystallizationtime,andbroadermeltingrangewhencomparedwithlinearPP.

Inourpreviousstudy,LCBPPswithdifferentLCBlevelwerepreparedbymeltgraftinginthepresenceofperoxideandpolyfunctionalmonomer,andtheirlinearviscoelasticpropertieswerealsostudied.ThepurposeofthisarticleistoinvestigatethenonisothermalcrystallizationkineticsofLCBPPswithdifferentLCBlevelcomparedwithlinearPP.Severalnonisothermalcrystallizationkineticequationswereused.Thenecessarydatawereobtainedfromdifferentialscanningcalorimetry(DSC)thermogram.ThekineticparameterssuchastheOzawaexponentandtheactivationenergieswerecalculated.Inaddition,thecrystalmorphologyoflinearPPandLCBPPswasalsostudiedbypolarizedopticalmicroscopy(POM).SamplepreparationLCBPPswithdifferentLCBlevelwerepreparedbymeltinggraftinginthepresenceof2,5-dimethyl-2,5(tbutylperoxy)hexaneperoxideandpentaerythritoltriacrylate(PETA)polyfunctionalmonomerinmixerat1808C;thedetailsofthepreparationprocessandcharacterizationbyrheologymethodswerediscussedinRef.15.Theformulation,zero-shearviscosity,andLCBlevelofsampleswerelistedinTableI,whereZ0andLCB/104Cweredeterminedbyrheologymethod.LCBlevelofD3cannotbecalculatedaccuratelybecauseitslongerrelaxationtimeislargerthanthemaximumrelaxationtimethatcanbedeterminedfromourexperiments.However,itcanbeconfirmedthatLCBlevelofD3ishigherthanthatofD2.DifferentialscanningcalorimetryThermalanalysisofthesampleswascarriedoutwithadifferentialscanningcalorimeter(DSC)instrumentundernitrogenatmosphere.Tostudythecrystallizationandmeltingbehaviors,thesamplesabout4mgweremeltedat2008Cfor5mintoeliminatethermalhistory,followedbycoolingatarateof108C/minandthecrystallizationthermogramwasmeasured.Thetemperatureofpeakswastakenasthecrystallizationtemperature,Tc.Assoonasthetemperaturereached508C,itwasreheatedagainatarateof108C/minandthemeltingthermogramwasmeasured.Theprocedurefornonisothermalcrystallizationwasasfollows:thesamplesweremeltedat200Cfor5mintoeliminatethermalhistory,andthencooledtoroomtemperatureat5,10,20,30,and40oc/min,respectively.TheexothermalcurvesofheatflowasafunctionoftemperaturewererecordedtoanalyzethenonisothermalcrystallizationprocessofPPandLCBPPs.PolarizedopticalmicroscopyAsamplewassandwichedbetweentwomicroscopecoverglasses,meltedat2008Cfor5mintoeliminatethermalhistory,andthencooledtoroomtemperatureat208C/min.RESULTSANDDISCUSSIONCrystallizationandmeltingbehaviorofPPandLCBPPsFigure1(a,b)showscoolingandheatingthermogramsofPPandLCBPPs,andthecorrespondingcrystallizationandmeltingparametersdeterminedfromFigure1aregiveninTableII.ItcanbeseenfromcoolingthermogramsinFigure1(a)thatthecrystallizationtemperatures(Tc)ofLCBPPsarehigherthanthatofPP.AsshowninTableII,TcofPPis115.38CandTcofD1,D2,andD3is130.8,132.0,and132.18C,respectively.ItisclearthatthepresenceofLCBstructuremakesTcofPPimprovemorethan158C,however,TcincreasesslightlywithLCBlevel.Furthermore,incaseofLCBPPs,asmallshoulderonthecoolingthermogramscanbeobserved.ItcanbebelievedthattheshoulderrelatedtothepresenceofLCBstructure,whichwillbediscussedlater.ThesubsequentreheatingthermogramsofPPandLCBPPsareshowninFigure1(b).Themeltingtemperature(Tm)andtheenthalpiesoffusion(DHm)arealsolistedinTableII.ItcanbeseenthatthethermogramsforPPandLCBPPsallshowedsinglemeltingpeak.TmofLCBPPsshifttohighertemperaturecomparedwiththatofPP,moreover,theshapeofmeltingpeaksforLCBPPsisbroaderthanthatofPP,whichsuggeststhatthecrystallinesofPParemoreperfectthanthatofLCBPPs.ThecrystallinityofPPcanbedeterminedfromheatingscansusingthefollowingequations:ThecrystallinityofPPandLCBPPswascalculatedbyeq.(1)andthedatawerelistedinTableII.AsshowninTableII,thecrystallinityofLCBPPsishigherthanthatofPP,indicatingthatthebranchedchainscanactasanucleatingagentandhelptoincreasethecrystallinityofPP.NonisothermalcrystallizationbehaviorofPPandLCBPPsFigure1showsthenonisothermalcrystallizationexothermalcurvesofPPandLCBPP(sampleD2)atdifferentcoolingrates.Someusefulparameterssuchastheonsetcrystallizationtemperature(To),thepeaktemperature(Tp),andtheendcrystallizationtemperature(Te)canbeobtainedfromthesecurves,andthevalueswerelistedinTableIII.Asexpected,theexothermicpeakshiftedtolowertemperatureandbecamebroaderwithcoolingrateincreasingforallsamples.AsshowninTableIII,TpofLCBPPsishigherthanthatofPPatgivencoolingrate,indicatingthatthecrystallizationrateincreasedandthedegreeofsupercoolingrequiredforthecrystallizationreducedwhenLCBwasintroducedontoPPbackbone.Moreover,atthegivencoolingrate,TpincreasedslightlywithLCBlevelincreasing;however,italmostdoesnotchangeagainwhenLCBlevelachievedagivenvalue,i.e.,D2.Inaddition,asmallshoulderappearedontheLCBPPscoolingcurvesatlowertemperatureandbecameunconspicuouswiththeincreasingcoolingrate.Toourknowledge,thisphenomenonwasnotreportedinotherlinear,grafted,orbranchedpolymers.Theexactreasonwasnotknown,butitcanbecertainthattheshoulderisrelatedtothepresenceofLCBstructure,whichinfluencesthecrystallizationkineticprocessofPP.Thisphenomenonwillbediscussedinfollowinganalysisofnonisothermalcrystallizationkineticparameters.ObservationofcrystalmorphologybyPOMThecrystalmorphologyofPPandLCBPPswasobservedthroughPOM.Figure9showsthepolarizedmicrographsofPPandLCBPPsnonisothermalcrystallizedatacoolingrateof208C/min.ThelinearPPshowswell-definedspheruliteswitha‘‘Maltesecross’’structure,whereasLCBPPsshowmorenucleationsitesandverytinycrystallites,indicatingthatLCBstructureactsasanucleatingagent.ItcanbeobservedthattheintroducingofLCBacceleratedthenucleation,buttheradialgrowthrateofthespherulitesdecreased.Thisobservationagreeswiththeanalysisaboutnonisothermalkineticparameters.Ontheotherhand,itwasobservedthatthespheruliticdevelopmentofPParisefromsporadicnucleation,whilethatofLCBPParisefrominstantaneousnucleation.Homogeneousnucleationstartsspontaneouslybychainaggregationbelowthemeltingpoint,whichrequiresalongertime,whereasheterogeneousnucleationformssimultaneouslyassoonasthesamplereachesthecrystallizationtemperature.23Consideringtheabove-mentionedkineticanalysis,itcanbeconcludedthatLCBPPcrystallizesmainlyviaheterogeneousnucleation,whilePPcrystallizesviabothheterogeneousnucleationandhomogeneousnucleation.CONCLUSIONSThenonisothermalcrystallizationkineticsoflinearPPandLCBPPswereinvestigatedsystematicallybytheDSCtechnique.Theresultsshowthatatvariouscoolingrates,theexothermicpeaksofLCBPPsdistinctlyshiftedtohighertemperaturescomparedwiththatoflinearPP.TheAvrami,Jeziorny,Ozawa,andMomethodscandescribethenonisothermalcrystallizationprocessoflinearPPandLCBPPverywell.TheAvramiexponentnofLCBPPsissmallerthanthatoflinearPPatvariouscoolingrate,indicatingthattheintroducingofLCBinfluencesthemechanismofnucleationandthegrowthofPP,moreover,thecoolingratehasweakeffectonthevalueofnforLCBPPscomparedtolinearPP.ThevalueofZcforLCBPPsishigherthanthatforlinearPPandthevalueoft1/2forLCBPPsislowerthanthatforlinearPP,suggestingthatthebrancheshavetheroleofheterogeneousnucleatingagentandacceleratedthecrystallizationprocess.TheactivationenergyDEoflinearPPandLCBPPswascalculatedusingKissingermethod.TheresultshowsthatthevaluesofDEforLCBPPsarehigherthanthatforPP,indicatingthatthepresenceofLCBbaffledthetransferofmacromolecularsegmentsfromPPmelttothecrystalgrowthsurface.Moreover,thevalueofDEdecreaseslightlywithLCBlevelincreasing.ThecrystalmorphologyofPPandLCBPPswasobservedthroughPOM.TheresultsshowthatthespherulitesofLCBPPsaremuchsmallerthanthatofPP,indicatingthatLCBstructureactsasnucleatingagent.

線性和長鏈支化聚丙烯的結晶行為摘要:線性和長鏈支化聚丙烯的非等溫結晶動力學(LCBPP)在不同冷卻速率下進行了差示掃描量熱法(DSC)。有幾種方法，比如阿夫拉米，小澤一郎和Jeziorny描述線性PP的結晶過程和LCBPPs在非等溫條件下的不同LCB水平。而t1/2和F(T)的值表明，LCB異質成核劑的作用,加速PP的結晶過程。此外,基辛格的方法被用來評估線性PP和LCBPPs的活化能。結果表明,LCBPPs的活化能高于線性頁，LCB擋板的存在從PP熔體高分子領域的轉移到晶體生長的表面。此外,線性PP和LCBPPs的晶體結構是通過偏振光學顯微鏡觀察(POM)和細觀察LCBPP球晶得來的。關鍵詞:聚丙烯、長鏈分支、非等溫結晶動力學簡介等規聚丙烯(iPP)有許多可取的和有益的物理特性,如低密度、高熔點、耐化學性。因此,iPP已經廣泛應用于工業和商業應用。然而,iPP是線型高分子,因此,它不顯示在融化狀態下的低熔體強度和應變硬化行為,這限制了它的使用在應用程序如熱成型、發泡、吹塑。最有效的方法來改善PP的熔體強度是引入長鏈分支(LCB)到PP骨干。近年來對LCB分子結構之間的關系和PP的流變行為有相當大的興趣。分子結構的變化不僅會影響流變性質也影響PP的結晶屬性。然而,線性和長鏈支化聚丙烯的結晶行為(LCBPP)很少被詳細研究。有許多研究是關于接枝PP的結晶。人們普遍認為接枝PP部分矩陣作為成核劑能夠加速結晶率。推測PP-g-MA和PP之間的不同的結晶行為是由于鏈相互作用,如氫鍵之間水解馬來酸酐組。對LCB沒有具體的定義,然而,從流變學的觀點來看,一個分支行為所需的長度作為一個長鏈分支2Me。因此,PP碎片的分子結構和LCBPP是非常不同的。因此,LCBPP的結晶行為和結晶形態不同于線性聚丙烯或接枝PP。它可以從有限的文獻總結得知,LCBPP的結晶溫度高,結晶時間短,與線性PP相比有更廣泛的范圍融化。在我們先前的研究中,LCBPPs與LCB不同的水平是由于融化嫁接在過氧化氫的存在和多官能團單體決定的,同時對線性粘彈性性能也進行了研究。本文的目的是調查的非等溫結晶動力學LCBPPs和不同水平的LCB與幾種非等溫結晶動力學方程的線性關系。從差示掃描量熱法(DSC)熱法得到必要的數據。以及小澤等動力學參數指數和激活能量的計算。此外,也研究了線性PP的晶體結構和LCBPPs偏振光學顯微鏡(POM)。樣品制備LCBPPs與不同水平的LCB被融化嫁接前的準備，將tbutylperoxy，己烷和季戊四醇，PETA多官能單體在180oc混合器中混合;制備過程的細節和特征流變學方法過討論了,zero-shear粘度、和LCB水平的樣本是列在表一。LCBD3水平無法準確計算,因為它再弛豫時間大于最大弛豫時間可以確定從我們的實驗。然而,它可以證實,LCBD3水平是高于D2。差示掃描量熱法在氮氣環境中對熱分析的樣品進行了差示掃描量熱計(DSC)儀器。研究結晶和熔融行為,4毫克樣品在200oc下大約融化5分鐘,消除熱歷史,緊隨其后的是10oc/分鐘的速度的冷卻和結晶熱法的測量。溫度峰值作為結晶溫度,Tc。當溫度達到50攝氏度時,它又以10oc/分鐘的速度進行加熱和熔化熱法的測量。非等溫結晶的過程如下:樣本用5分鐘在200oc下融化來消除熱歷史,然后在5、10、20、30和40oc/分鐘分別冷卻到室溫。熱流的放熱曲線作為溫度的函數記錄分析聚丙烯的非等溫結晶過程和LCBPPs。偏振光學顯微鏡線性PP和LCBPPs的晶體結構研究用偏光顯微鏡。樣本被夾在兩個顯微鏡蓋眼鏡,用5分鐘在200oc下融化來消除熱歷史,然后以20oc/分鐘冷卻到室溫。結果與討論PP的結晶和熔融行為和LCBPPs圖1(a,b)顯示PP和LCBPPs冷卻和加熱溫譜圖,相應的結晶和熔融參數在表二與圖1給出決定。從冷卻熱分析圖可以看出圖1(a),LCBPPs的結晶溫度(Tc)是高于PP。如表二所示,PP的Tc是115.3oc而D1、D2、D3分別是130,132和132.1oc,