聚丙烯中英文對照外文翻譯文獻

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(jié)晶行為摘要:線性和長鏈支化聚丙烯的非等溫結(jié)晶動力學(xué)(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(jié)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(zhì)成核劑的作用,加速PP的結(jié)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(jié)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(lǐng)域的轉(zhuǎn)移到晶體生長的表面。此外,線性PP和LCBPPs的晶體結(jié)構(gòu)是通過偏振光學(xué)顯微鏡觀察(POM)和細(xì)觀察LCBPP球晶得來的。關(guān)鍵詞:聚丙烯、長鏈分支、非等溫結(jié)晶動力學(xué)簡介等規(guī)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(xué)性。因此,iPP已經(jīng)廣泛應(yīng)用于工業(yè)和商業(yè)應(yīng)用。然而,iPP是線型高分子,因此,它不顯示在融化狀態(tài)下的低熔體強度和應(yīng)變硬化行為,這限制了它的使用在應(yīng)用程序如熱成型、發(fā)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(jié)構(gòu)之間的關(guān)系和PP的流變行為有相當(dāng)大的興趣。分子結(jié)構(gòu)的變化不僅會影響流變性質(zhì)也影響PP的結(jié)晶屬性。然而,線性和長鏈支化聚丙烯的結(jié)晶行為(LCBPP)很少被詳細(xì)研究。有許多研究是關(guān)于接枝PP的結(jié)晶。人們普遍認(rèn)為接枝PP部分矩陣作為成核劑能夠加速結(jié)晶率。推測PP-g-MA和PP之間的不同的結(jié)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(xué)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(jié)構(gòu)和LCBPP是非常不同的。因此,LCBPP的結(jié)晶行為和結(jié)晶形態(tài)不同于線性聚丙烯或接枝PP。它可以從有限的文獻總結(jié)得知,LCBPP的結(jié)晶溫度高,結(jié)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(diào)查的非等溫結(jié)晶動力學(xué)LCBPPs和不同水平的LCB與幾種非等溫結(jié)晶動力學(xué)方程的線性關(guān)系。從差示掃描量熱法(DSC)熱法得到必要的數(shù)據(jù)。以及小澤等動力學(xué)參數(shù)指數(shù)和激活能量的計算。此外,也研究了線性PP的晶體結(jié)構(gòu)和LCBPPs偏振光學(xué)顯微鏡(POM)。樣品制備LCBPPs與不同水平的LCB被融化嫁接前的準(zhǔn)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(xì)節(jié)和特征流變學(xué)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(zhǔn)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(huán)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(jié)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(jié)晶熱法的測量。溫度峰值作為結(jié)晶溫度,Tc。當(dāng)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(jié)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(shù)記錄分析聚丙烯的非等溫結(jié)晶過程和LCBPPs。偏振光學(xué)顯微鏡線性PP和LCBPPs的晶體結(jié)構(gòu)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(jié)果與討論PP的結(jié)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(yīng)的結(jié)晶和熔融參數(shù)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(jié)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,