毛細(xì)管流變儀

毛細(xì)管流變儀第1頁/共138頁1Introduction

Polymersareusedbecause:TheyarecheaptoformintoshapeinmoltenstateTherefore,Weneedtounderstandhowtheyflowwhenmoltenalsoimportantin:foodprocessing,pharmaceuticals,paints,inks,pastes,slurriesetc...

VeryimportantinPolymerProcessing第2頁/共138頁But,moltenpolymersarecomplicatedsystems...TemperaturedependentRatedependentTimedependentWorkdependent(andthat’sbeforeweaddlubricants,fillers,plasticisers,foamingagentsetc…!)Inbetweenaliquidandasolid第3頁/共138頁

InfluencesonViscosity

molecularstructureofsampletemperaturepressuretimeshearrate(T,p,t,g)

=g..第4頁/共138頁Shearviscositydefinitiong-shearrate.

t-shearstress

=g.

-shearviscosityViscosityisameasureofresistanceofafluidagainsttheappliedshearforce.ShearviscosityisonlyonepartofRheology.

Itisthedominanteffectforpressureinextruders,injectionmouldingmachinesanddies.第5頁/共138頁TypicalprocessshearratesRelaxationCoatingFreesurfaceMixingExtrusionInjectionmoulding第6頁/共138頁Whydoweneedahigh-pressurecapillaryrheometer?Theapplicationisimportantlog/s-1DMAOsc./Rot.rheometerHighpressurecapillaryrheometerViscosities:(low-),middle-tohigh-viscousQuantities:Shear-andextensionalviscosity,wallslip

relaxation,PVT,Flowinstabilities10-110-3Levelling104101Extrusion,InjectionMoulding100102Mixing103106RollCoating,SprayingViscosities:lowviscoustosolid-likeQuantities:Shearviscosity,yield,viscoelasticproperties,relaxationetc.Non-destructiveOscillaroryshearrot.rheometer:structural/lowshearmeasurements–

high-pressurecapillary:processingflowbehaviour第7頁/共138頁2.Structure2.16kg

Singlepointtest(generatesonenumber)MFIdie(2.095mmdiameter)

Definedbystandards(ISO1133)

Simple

Cheap

Easytouse

PressuredrivenMeltFlowIndexer(MFI)第8頁/共138頁MeltFlowIndexer(MFI)

Singlepointtest

Doesnotgenerateengineeringunits-(gramsper10minutes)

Mainlyashearflowmeasurement-neglectsextension

Verylowshearratetest (app=2.4MFI)But,第9頁/共138頁TypicalprocessshearratesRelaxationCoatingFreesurfaceMixingExtrusionInjectionmouldingMFItest第10頁/共138頁CapillaryRheometerMeasure:PressuredropPistonCapillarydiePressuretransducerPolymermeltSet:PistonspeedDieDim’s第11頁/共138頁CapillaryrheometryWeset:Temperature,pistonspeed,diegeometryWemeasure:Meltpressure(long&shortdies)Givingus:Shearstress(atarangeorrates)Extensionalstress(atarangeorrates)第12頁/共138頁CapillaryrheometryLongdie:shearShortdie:extension第13頁/共138頁3Shearviscosity完全發(fā)展區(qū)剪切應(yīng)力的計(jì)算管壁處第14頁/共138頁3Shearviscosity不可壓縮性流體剪切速率的計(jì)算第15頁/共138頁L2R3ShearviscosityGivenquantity:pistonspeedwallshearrateMeasuredquantity:pressuredropwallshearstressEntrancepressuredropShearpressuredropvMeasuredpressuredrop=+PLBARRELPLPlPwENTRANCELENGTH

FULLYDEVELOPEDFLOWREGION0Z0LsmallramextruderMeasuringPrinciple第16頁/共138頁P(yáng)ressuredropthroughacapillary/slitdie第17頁/共138頁Newtonianfluid

shearrate,

=4Q/r3

shearstress,

=Pr/2Lshearviscosity,

=/

ShearFlowAnalysis

g.g.(g).g.g.第18頁/共138頁CalculationofEntrancePressureDrops1.HistoricalBagley-MethodaccordingtoDIN11443

full

10203040HighshearrateLowshearrateL/DPges(L/D=0)=EntrancePressureDrop

????°°°°Principle:

MeasurementoftheFullPressureDropatconstantShearrateanddifferentL/DratioLinearextrapolationtoL/D=0E.B.Bagley,J.Appl.Physics28(1957),624

第19頁/共138頁CalculationofEntrancePressureDrops2.PracticalDifficultieswithHistoricalBagleyMethodfull10203040L/DnegativeEntrancePressureDrop!

?????Problems:linearextrapolationcanleadtophysicallyimpossibleresultsExtrapolationshowsverylargestandarddeviation第20頁/共138頁CalculationofEntrancePressureDrops3.ReasonsfortheErrorsinExtrapolationReasons:

atsmallL/D-valuesnon-linearitiesoccurforallsamplesatthemomentthereisnotheoreticalapproachathighL/D-valuesnon-linearitiesduetowallslip,compressibility...(theoreticalprediction)full

24681012L/DNon-linearitiesatsmallL/DHistoricalBagleyTruecurve?

????????Kelly,Coates,Dobbie,Fleming,Plastics,RubberandCompositesProcessingandApplications1996,vol.25,No.7,313.Datasnottruetoscale.第21頁/共138頁CalculationofEntrancePressureDrops4.Solution:Doublecapillarysystemfull

5101520L/DInnovation:

Measurement-noExtrapolationneeded!SimultaneousmeasurementoffullpressuredropalongcapillarydieandentrancepressuredroponorificediePshear=Pfull-PoOrificedie(pinholewithneglectableL/D-ratio)CapillarydiewithL/D=16第22頁/共138頁TheRosandDoubleCapillarySystemwithorificedieMeasurethedieentrancepressuredropdirectlyL2RvpentrancepshearPfullPfull=Pshear+Pentrancevpentranceleft:Capillarydie right:Orificedie第23頁/共138頁RabinowitschCorrection

第24頁/共138頁Fornon-NewtonianflowprofileRabinowitschCorrectionn=d(log)d(log).Correctedshearflow(polymermelts)Ifn=0.5,=1.25*c.4QR3Apparentshearrate(Newtonianmaterial)a=.polyethylene 0.3to0.6polypropylene 0.3to0.4PVC 0.2to0.5polyamide 0.6to0.9.

a.4QR33n+14nc=.Optional,buttrytokeepconsistency!第25頁/共138頁WallSlipcorrection第26頁/共138頁WallSlipAfundamentalassumptioninmostrheologyisvelocityatthemetalwall=0SlipiswellknowntooccurinPVC,HDPEandmetallocenecatalysedpolymers

Difficulttomeasure-canbeapproximatedusingcapillaryrheometrySlipisaffectedbyfillersandlubricants

第27頁/共138頁Evidenceofwallslip

第28頁/共138頁WallSlipCorrection4VsWallSlipNoWallSlipapp1/RResult:Dependencyofwallslipvelocityonshearstress(trueshearrate)slipshearfullQQQ+=Rv4sliptrueapp+g=g..2slip3true3appRv4R4Rp×+p×g=p×g..

Mooney,M.,J.Rheology

2,210(1931)第29頁/共138頁WallSlipMeasurement

Slipcomponentofflowrate,

Q=R2v

[Vs]mm/s[w]kPaPE

Vs=1.50(w/100)3.20

w

90kPaPVC

Vs=9.5(w/100)2.28

SometypicalslipvelocitiesManymaterialsonlyslipaboveacriticalstress,typically0.1MPa第30頁/共138頁ExtensionalFlowAnalysis第31頁/共138頁4ExtensionalFlowAnalysis第32頁/共138頁4ExtensionalFlowAnalysis第33頁/共138頁4ExtensionalFlowAnalysis第34頁/共138頁4ExtensionalFlowAnalysis第35頁/共138頁第36頁/共138頁第37頁/共138頁拉伸黏度是在實(shí)際紡絲過程即非穩(wěn)態(tài)拉伸流中的黏度。表觀拉伸黏度定義為：

第38頁/共138頁采用攝影的方法，對穩(wěn)態(tài)的絲條拍照，從照片量取纖維直徑沿軸向的變化數(shù)據(jù)第39頁/共138頁第40頁/共138頁ExtensionalFlowAnalysis第41頁/共138頁5meltfracture第42頁/共138頁第43頁/共138頁第44頁/共138頁第45頁/共138頁第46頁/共138頁第47頁/共138頁第48頁/共138頁第49頁/共138頁第50頁/共138頁第51頁/共138頁第52頁/共138頁第53頁/共138頁第54頁/共138頁第55頁/共138頁第56頁/共138頁第57頁/共138頁實(shí)際成型加工及流變測量中，物料流動狀態(tài)受諸多因素影響，常常出現(xiàn)不穩(wěn)定流動情形。許多情況下，流場邊界條件存在一個(gè)臨界值。一旦超越該臨界值，就會發(fā)生從層流到湍流，從平整到波動，從管壁無滑移到有滑移的轉(zhuǎn)變，破壞了事先假定的穩(wěn)定流動條件。研究這類熔體流動不穩(wěn)定性及壁滑現(xiàn)象是從“否定”意義上討論高分子的流變性質(zhì)，具有重要意義。該問題的工程學(xué)意義是，當(dāng)工藝過程條件不合適，會造成制品外觀、規(guī)格尺寸及材質(zhì)均一性嚴(yán)重受損，直接影響產(chǎn)品的質(zhì)量和產(chǎn)率，嚴(yán)重時(shí)甚至使生產(chǎn)無法進(jìn)行。高分子流動不穩(wěn)定性主要表現(xiàn)為擠出過程中的熔體破裂現(xiàn)象、拉伸過程（纖維紡絲和薄膜拉伸成型）中的拉伸共振現(xiàn)象及輥筒加工過程中的物料斷裂現(xiàn)象等。熔體在管壁發(fā)生滑移與此類現(xiàn)象密切相關(guān)?？梢钥隙ǖ卣f，這些現(xiàn)象與高分子液體的非線性粘彈行為，尤其是彈性行為有關(guān)，是高分子液體彈性湍流的表現(xiàn)。第58頁/共138頁熔體的擠出破裂行為：在擠出過程中，當(dāng)熔體剪切速率超過某一臨界剪切速率時(shí)，擠出物表面開始出現(xiàn)畸變的現(xiàn)象。表現(xiàn)為：最初表面粗糙，而后隨剪切速率（或切應(yīng)力）的增大，分別出現(xiàn)波浪型、鯊魚皮型、竹節(jié)型、螺旋型畸變，直至無規(guī)破裂。

第59頁/共138頁從現(xiàn)象上分，擠出破裂行為可歸為兩類：一類稱LDPE（低密度聚乙烯）型。破裂特征是先呈現(xiàn)粗糙表面，當(dāng)擠出超過臨界剪切速率發(fā)生熔體破裂時(shí)，呈現(xiàn)無規(guī)破裂狀。屬于此類的材料多為帶支鏈或大側(cè)基的聚合物，如聚苯乙烯、丁苯橡膠、支化的聚二甲基硅氧烷等。第60頁/共138頁一類稱HDPE（高密度聚乙烯）型。熔體破裂的特征是先呈現(xiàn)粗糙表面，而后隨著剪切速率的提高逐步出現(xiàn)有規(guī)則畸變，如竹節(jié)狀、螺旋型畸變等。很高時(shí)，出現(xiàn)無規(guī)破裂。屬于此類的材料多為線型分子聚合物，如聚丁二烯、乙烯-丙烯共聚物，線型的聚二甲基硅氧烷、聚四氟乙烯等。這種分類不夠嚴(yán)格，有些材料的熔體破裂行為不具有這種典型性第61頁/共138頁流變曲線的差別：屬于LDPE型的熔體，其流變曲線上可明確標(biāo)出臨界剪切速率或臨界剪切力位置，曲線在臨界剪切速率之前為光滑曲線，之后出現(xiàn)波動，但基本為一連續(xù)曲線屬于HDPE型的熔體，其流變曲線在達(dá)到臨界剪切速率后變得復(fù)雜。隨著剪切速率的提高，流變曲線出現(xiàn)大幅度壓力振蕩或剪切速率突變，曲線不連續(xù)，有時(shí)使流變測量不能進(jìn)行第62頁/共138頁造成熔體破裂現(xiàn)象的機(jī)理十分復(fù)雜，肯定地說，它與熔體的非線性粘彈性、與分子鏈在剪切流場中的取向和解取向（構(gòu)象變化及分子鏈松弛的滯后性）、纏結(jié)和解纏結(jié)及外部工藝條件諸因素有關(guān)。從形變能的觀點(diǎn)看，高分子液體的彈性是有限的，其彈性貯能本領(lǐng)也是有限的。當(dāng)外力作用速率很大，外界賦予液體的形變能遠(yuǎn)遠(yuǎn)超出液體可承受的極限時(shí)，多余能量將以其它形式表現(xiàn)出來，其中產(chǎn)生新表面、消耗表面能是一種形式，即發(fā)生熔體破裂。第63頁/共138頁ElongationalviscosityinfluenceConvergenceintoaflatentrydieLDPEHDPEAlsoimportantinanyconvergentordivergentpartofaprocess第64頁/共138頁Tordella的流動雙折射實(shí)驗(yàn)對LDPE型熔體，其應(yīng)力主要集中在口模入口區(qū)，且入口區(qū)的流線呈典型的喇叭型收縮，在口模死角處存在環(huán)流或渦流。當(dāng)剪切速率較低時(shí)，流動是穩(wěn)定的，死角處的渦流也是穩(wěn)定的，對擠出物不產(chǎn)生影響。但當(dāng)剪切速率后，入口區(qū)出現(xiàn)強(qiáng)烈的拉伸流，其造成的拉伸形變超過熔體所能承受的彈性形變極限，強(qiáng)烈的應(yīng)力集中效應(yīng)使主流道內(nèi)的流線斷裂，使死角區(qū)的環(huán)流或渦流乘機(jī)進(jìn)入主流道而混入口模。主流線斷裂后，應(yīng)力局部下降，又會恢復(fù)穩(wěn)定流動，然后再一次集中彈性形變能，再一次流線斷裂。這樣交替輪換，主流道和環(huán)流區(qū)的流體將輪番進(jìn)入口模。這是兩種形變歷史和攜帶能量完全不同的流體，可以預(yù)見，它們擠出時(shí)的彈性松弛行為也完全不同，由此造成口模出口處擠出物的無規(guī)畸變。第65頁/共138頁對HDPE型熔體，其流動時(shí)的應(yīng)力集中效應(yīng)主要不在口模入口區(qū)，而是發(fā)生在口模內(nèi)壁附近，口模入口區(qū)不存在死角環(huán)流。低剪切速率時(shí)，熔體流過口模壁，在壁上無滑移，擠出過程正常。當(dāng)剪切速率增高到一定程度，由于模壁附近的應(yīng)力集中效應(yīng)突出，此處的流線會發(fā)生斷裂（后面將說明，流線斷裂的一個(gè)原因是由于分子鏈解纏結(jié)造成的）。又因?yàn)閼?yīng)力集中使熔體貯能大大增加，當(dāng)能量累積到超過熔體與模壁之間的摩擦力所能承受的極限時(shí)，將造成熔體沿模壁滑移，熔體突然增速（柱塞上壓力下降），同時(shí)釋放出能量。釋能后的熔體又會再次與模壁粘著，從而再集中能量，再發(fā)生滑移。第66頁/共138頁這種過程周而復(fù)始，將造成聚合物熔體在模壁附近“時(shí)滑時(shí)粘”，表現(xiàn)在擠出物上呈現(xiàn)出竹節(jié)狀或套錐形的有規(guī)畸變。當(dāng)剪切速率再增大時(shí)，熔體在模壁附近會出現(xiàn)“全滑動”，這時(shí)反而能得到表面光滑的擠出物，即所謂第二光滑擠出區(qū)。此時(shí)應(yīng)力集中效應(yīng)將轉(zhuǎn)到口模入口區(qū)。在極高的剪切速率下，熔體流線在入口區(qū)就發(fā)生擾亂，這時(shí)的擠出物必然呈無規(guī)破裂狀。第67頁/共138頁1．3影響熔體擠出破裂行為的因素一切能夠影響熔體彈性的因素，都將影響聚合物熔體的擠出破裂行為。這些因素大致可分為三類：一是口模的形狀和尺寸；二是擠出成型過程的工藝條件；三是擠出物料的性質(zhì)。第68頁/共138頁1．3．1口模形狀、尺寸的影響口模的入口角對LDPE型熔體的擠出破裂行為影響很大。實(shí)驗(yàn)發(fā)現(xiàn)，當(dāng)入口區(qū)為平口型（入口角）時(shí)，擠出破裂現(xiàn)象嚴(yán)重。而適當(dāng)改造入口區(qū)，將入口角減小變?yōu)槔瓤谛蜁r(shí)，擠出物外觀有明顯改善；且開始發(fā)生熔體破裂的臨界剪切速率（或臨界剪切應(yīng)力）增高。口模的定型長度L對熔體破裂行為也有明顯影響。對于LDPE型熔體，已知造成熔體破裂現(xiàn)象的根源在于入口區(qū)的流線擾動。這種擾動會因聚合物熔體的松弛行為而減輕，因而定型長度L越長，彈性能松弛越多，熔體破裂程度就越輕，對于HDPE型流體，熔體破裂現(xiàn)象的原因在于模壁處的應(yīng)力集中效應(yīng)，因而定型長度越長，擠出物外觀反而不好。第69頁/共138頁1．3．2擠出工藝條件和物料性質(zhì)的影響給出低密度聚乙烯在不同擠出速度（不同剪切速率）下通過同一個(gè)口模時(shí)，測得的壓力波動沿口模軸向的分布圖。已知低密度聚乙烯通過口模時(shí)，其彈性形變主要發(fā)生在入口區(qū)。，擠出速度越小，材料發(fā)生的彈性形變小，且形變得以松弛的時(shí)間較長，因此熔體內(nèi)的壓力波動幅度較小。適當(dāng)升高熔體溫度是另一個(gè)典型例子。熔體溫度升高，粘度下降，會使松弛時(shí)間縮短，從而使擠出物外觀得以改善。因此在工廠中，升高料溫（特別是口模區(qū)溫度）是解決熔體破裂的快速補(bǔ)救辦法。第70頁/共138頁從材料角度看，平均分子量大的物料，最大松弛時(shí)間較長，容易發(fā)生熔體破裂。而在平均分子量相等的條件下，分子量分布較寬（較大）的物料的擠出行為較好，發(fā)生熔體破裂的臨界剪切速率較高，這可能與寬分布試樣中低分子量級分的增塑作用有關(guān)。填料的作用。無論填加填充補(bǔ)強(qiáng)劑還是軟化增塑劑，都有減輕熔體破裂程度的作用。這一是因?yàn)槟承┸浕瘎┑脑鏊茏饔?；二是填料本身無熵彈性，填入后使能夠發(fā)生破裂的熔體比例減少。第71頁/共138頁AdeeperlookinsideWhathappensintheentrancezoneofacapillarydie?

achangeincross-sectionleadstoaentrance-pressure-dropbecauseof:ElasticstringingAccelerationsecondaryflow

Extensional,viscousflowPressuretransducerCapillarydie第72頁/共138頁ComparisonofTypicalShearData第73頁/共138頁ComparisonofTypicalExtensionData第74頁/共138頁TypicalPolymerProcessingTemperatures1.Polyolefins:~190°CPolyethylene(HDPE,LDPE,LLDPE)Polypropylene(PP)2.PVC:~165-180UPVCandplasticised3.EngineeringPolymers:~240-300°C

Nylon,PET,ABS4.Rubbers:~80-100°C

第75頁/共138頁Cogswell:EntrancePressureDropExtensionalViscosityShearviscositycurve1101001000110100100010000100000Correctedshearrate[1/s]Shearviscosity[Pas]sample1sample2Extensionalviscositycurve10100110100100010000Extensionalrate[1/s]Extensionalviscosity[kPas]Differencesonlyinextension(Structuresensitivity)BenefitsofCapillaryRheometry第76頁/共138頁ComparisonofDatafromCapillary&RotationalRheometersPolypropyleneMeasuredat190C

第77頁/共138頁Lowviscositysamplescanbeinvestigatedunder

processingconditions

ComparisonofDatafromCapillary&RotationalRheometers第78頁/共138頁AnalysisofFlowCurvesOnline-pressuredrophomogeneityofyoursampleimportantfactorforquality(influenceofMixing,pre-shearetc.)homogeneous:inhomogeneous:g.tPrinciple:Rampinsteps第79頁/共138頁AnalysisofinhomogeneitiesPressuredeviationsgivesapprox.averagelengthscaleEquilibriumDtDtDVmainlyusedforpolymerblends,suspensions...第80頁/共138頁3commoncorrectionsin

capillaryrheometry1.Bagley(entrancepressurelosses)2.Rabinowitsch(non-Newtonianflow)3.WallSlip(non-zerovelocityatdiewall)第81頁/共138頁FlowcurvesMeasurementSequenceofshearstepsmeasurement:DvttStepRatepapp=g.htappApparentvalues-datahastobecorrected.第82頁/共138頁AdvantagesofCapillaryRheometryPressuredrivenMimicstheprocess(flowthroughadie/nozzle)SimpletouseRobustSimpletointerpretAccuratedrivesystemAccuratetemperaturecontrol*engineer’spointofview第83頁/共138頁AdvantagesofCapillaryRheometryWideshearraterange,from0.1->100,000/sShearandextensionAbsoluteData(Bagley,Rabinowitsch,wallslip)Density,compressibilityDieswell&ElasticityUniaxialextension*rheologist’spointofview第84頁/共138頁RangeoftestsonRosandRheometers第85頁/共138頁TestProcedureI1.Selectthetypeoftest2.Selectthecapillarydie(s)3.Selectthepressuretransducer(s)4.Setmachinetemperature5.Setmachineparameters

-overloadlimits,equilibriumdetermination6.Runtest第86頁/共138頁TestProcedureII1.Chargethebarrel2.Manualcompression3.Starttest4.Pre-teststages

-compression(2)atsetspeed

-pre-heat(2)totaltime:9mins*5.Teststages*dependsonborediameter第87頁/共138頁Rheometersoftware第88頁/共138頁Rheometersoftware

resultsanalysis第89頁/共138頁1.SteadyshearTest:Dataobtained:Uses:RangeofconstantshearratesLongdieandoptionalshortdieShearstressandshearviscosityatarangeofshearratesDiedesign,extruderdesign,pressuredropprediction,flowmodelling,qualitycontrol,development第90頁/共138頁1.SteadyShear第91頁/共138頁1.SteadyShearCapillarywallshearrateisonlydependentupondiediameter,forasetpistonspeed.Typicalshearrates:*0.5mm?dies:50-100,000s-11mm?dies: 10-15,000s-12mm?dies: 1-1,500s-1StandardSpeedmachine第92頁/共138頁SteadyShear-testpressures第93頁/共138頁SteadyShear-typicalresults第94頁/共138頁SteadyShear-typicalresults第95頁/共138頁2.ExtensionalViscosityTest:Dataobtained:Uses:RangeofconstantshearratesLongdieandshortdieExtensionalstressandextensionalviscosityatarangeofshearratesDiedesign,pressuredropprediction,flowmodelling,qualitycontrol,development,filmblowing,fibrespinning第96頁/共138頁2.Shear/extension-typicalresultse=9(n+1)2(Dpe)2322.第97頁/共138頁Extension-typicalresults第98頁/共138頁3.MeltFractureTest:Dataobtained:Uses:Examinesareasofmeltinstability Longdieand/orshortdie,or2materialsAccuratedeterminationoftheconditionswhereinstabilityoccursDiedesign,profileextrusion,troubleshooting,injectionmouldingHDPE,PVC,heavilyfilled第99頁/共138頁3.MeltFracture第100頁/共138頁3.Evidenceofmeltfracture第101頁/共138頁4.MaterialdegradationTest:Dataobtained:Uses:RangeofshearrateswithwaitstagesLongdieand/orshortdieShearandextensionvaryingwithtimeatarangeofshearratesTimedependentmaterialsMoisturedependentmaterialsResidencetimedesignTroubleshooting第102頁/共138頁4.Materialdegradation第103頁/共138頁5.LowspeeddegradationTest:Dataobtained:Uses:ConstantlowshearrateLongdieand/orshortdieShearandextensionvaryingwithtimeataconstantshearrateTimedependentmaterialsMoisturedependentmaterialsResidencetimedesignTroubleshooting第104頁/共138頁5.Lowspeeddegradation第105頁/共138頁6.StressrelaxationTest:Dataobtained:Uses:PressuredecayfromconstantrateLongdieand/orshortdieDecayinpressureovertime-indicativeofelasticbehaviourTimedependentmaterialsHighlyelasticmaterialsQualitycontrolThermoforming第106頁/共138頁6.Stressrelaxation第107頁/共138頁6.Stressrelaxationresults

LDPEwithMg(OH)2filler第108頁/共138頁7.Flow/NoflowTest:Dataobtained:Uses:Constantshearrateastemperaturedecreases,singledieMinimumflowtemperatureProcessdesignMaterialspecification第109頁/共138頁7.Flow/Noflow第110頁/共138頁8.ManualtestTest:Dataobtained:Uses:Afterinitialheat-up,takeovermanualcontrol&takedatapointswheneverShear/extensionaldata,testpressuresInitialinvestigationEstablishconditionsbeforetesting第111頁/共138頁9.LowlevelscriptTest:Dataobtained:Uses:ProgramtestyourselfWhateveryouwantNon-standardtestse.g.crosslinking*needadetailedunderstandingofhowthemachineworks第112頁/共138頁10.WallslipTest:Dataobtained:Uses:Steadyshearusing3dieswithsameL:Dratio,differentdiametersSlipvelocityvs.shearstressDiedesignProcessdesignTroubleshootingFillereffects第113頁/共138頁10.Wallslip第114頁/共138頁10.Wallslip第115頁/共138頁11.PVT/DensitytestTest:Dataobtained:Uses:CompressesmeltSpecialplugdie&pistontipMeltcompressibility(versuspressure)Meltdensity(5%)FlowsimulationFiller&additiveinvestigationMaterialspecificationTroubleshooting第116頁/共138頁11.PVT/Densitytest第117頁/共138頁11.PVT/densitytest第118頁/共138頁11.PVT/densitytestresults

LDPEat200°C第119頁/共138頁12.FibrespinningtestTest:Dataobtained:Uses:Specialhaul-offmotor&scalesHaul-offspeedrampedupForcevshaul-offspeedBreakingpoint,tensileforceUniaxialextensionIndicationofbiaxialextensionEmpiricaldeterminationoftensilestrength第120頁/共138頁12.FibrespinningtestPracticalmeasurementF,vpUni-axialextension(HaulOff):Extensionalpropertiesatsmallextensionrates第121頁/共138頁HaulOff:ExampleLDPEatdifferenttemperatures

Maininterestisruptureforceundernon-isothermalconditionsLaun,Schuch.:J.Rheol.33(1989),119第122頁/共138頁13.DieSwellTestTest:Dataobtained:Uses:Lasergaugediametermeasurementofextrudateafterexitingdie

Extrudatediametervs.shearrateIndicationofelasticity(highshearrates)Profileextrusion,thermoforming,shrinkfilmetc.第123頁/共138頁13.DieSwellTest1.Die-SwellI(Laser-Die-Swell)Properties:Mono-orbiaxiallaser-systemMelt&DieCuttersallowmeasurementwithdefinedmelttensionResolution0.01mmCalculationofGandEaccordingtoCogswell第124頁/共138頁13.DieSwellTest2.Die-SwellI(Video-Die-Swell)

Properties:

higherresolution(0.01mm)twodimensionalmeasurementdetectionofthedieswelldynamics

第125頁/共138頁DieSwell:ExamplePP1hashigh-moleculartailinMwDcomparedtoPP2

Viscositycurvesnearly