聚丙烯中英文對(duì)照外文翻譯文獻(xiàn)

中英文對(duì)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(zhǎng)鏈支化聚丙烯的結(jié)晶行為摘要:線性和長(zhǎng)鏈支化聚丙烯的非等溫結(jié)晶動(dòng)力學(xué)(LCBPP)在不同冷卻速率下進(jìn)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(lái)評(píng)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(yè)，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(zhǎng)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(lái)的。關(guān)鍵詞:聚丙烯、長(zhǎng)鏈分支、非等溫結(jié)晶動(dòng)力學(xué)簡(jiǎn)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(diǎn)、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(qiáng)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(lái)改善PP的熔體強(qiáng)度是引入長(zhǎng)鏈分支(LCB)到PP骨干。近年來(lái)對(duì)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(huì)影響流變性質(zhì)也影響PP的結(jié)晶屬性。然而,線性和長(zhǎng)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(cè)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(lái)酸酐組。對(duì)LCB沒有具體的定義,然而,從流變學(xué)的觀點(diǎn)來(lái)看,一個(gè)分支行為所需的長(zhǎng)度作為一個(gè)長(zhǎng)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(xiàn)總結(jié)得知,LCBPP的結(jié)晶溫度高,結(jié)晶時(shí)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(tuán)單體決定的,同時(shí)對(duì)線性粘彈性性能也進(jìn)行了研究。本文的目的是調(diào)查的非等溫結(jié)晶動(dòng)力學(xué)LCBPPs和不同水平的LCB與幾種非等溫結(jié)晶動(dòng)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(dòng)力學(xué)參數(shù)指數(shù)和激活能量的計(jì)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(wú)法準(zhǔn)確計(jì)算,因?yàn)樗俪谠r(shí)間大于最大弛豫時(shí)間可以確定從我們的實(shí)驗(yàn)。然而,它可以證實(shí),LCBD3水平是高于D2。差示掃描量熱法在氮?dú)猸h(huán)境中對(duì)熱分析的樣品進(jìn)行了差示掃描量熱計(jì)(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(cè)量。溫度峰值作為結(jié)晶溫度,Tc。當(dāng)溫度達(dá)到50攝氏度時(shí),它又以10oc/分鐘的速度進(jìn)行加熱和熔化熱法的測(cè)量。非等溫結(jié)晶的過程如下:樣本用5分鐘在200oc下融化來(lái)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(gè)顯微鏡蓋眼鏡,用5分鐘在200oc下融化來(lái)消除熱歷史,然后以20oc/分鐘冷卻到室溫。結(jié)果與討論P(yáng)P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,