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外文翻译--PBT玻璃纤维增强复合材料水辅注塑成型的实验研究 英文.pdf

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外文翻译--PBT玻璃纤维增强复合材料水辅注塑成型的实验研究 英文.pdf

form7NovemberFig.1.Waterassistedinjectionmoldingcanproducepartsincorporatingboththickandthinsectionswithlessshrinkinvolved.Watermayalsocorrodethesteelmold,andsomematerialsincludingthermoplasticcompositesaredifficulttomoldsuccessfully.Theremovalofwateraftermoldingisalsoachallengeforthisnoveltechnology.Table1liststheadvantagesandlimitationsofwaterassistedinjectionmoldingtechnology.Correspondingauthor.Address259,WenHwa1stRoad,KweiSan,TaoYuan333,Taiwan.Emailaddressshihjungmail.cgu.edu.twS.J.Liu.CompositesScienceandTechnologyCOMPOSITES1.IntroductionWaterassistedinjectionmoldingtechnology1hasproveditselfabreakthroughinthemanufactureofplasticpartsduetoitslightweight,fastercycletime,andrelativelylowerresincostperpart.Inthewaterassistedinjectionmoldingprocess,themoldcavityispartiallyfilledwiththepolymermeltfollowedbytheinjectionofwaterintothecoreofthepolymermelt.Aschematicdiagramofthewaterassistedinjectionmoldingprocessisillustratedinageandwarpageandwithabettersurfacefinish,butwithashortercycletime.Thewaterassistedinjectionmoldingprocesscanalsoenablegreaterfreedomofdesign,materialsavings,weightreduction,andcostsavingsintermsoftoolingandpresscapacityrequirements2–4.Typicalapplicationsincluderodsandtubes,andlargesheetlikestructuralpartswithabuiltinwaterchannelnetwork.Ontheotherhand,despitetheadvantagesassociatedwiththeprocess,themoldingwindowandprocesscontrolaremorecriticalanddifficultsinceadditionalprocessingparametersareAbstractThepurposeofthisreportwastoexperimentallystudythewaterassistedinjectionmoldingprocessofpolybutyleneterephthalatePBTcomposites.Experimentswerecarriedoutonan80toninjectionmoldingmachineequippedwithalabscalewaterinjectionsystem,whichincludedawaterpump,apressureaccumulator,awaterinjectionpin,awatertankequippedwithatemperatureregulator,andacontrolcircuit.ThematerialsincludedvirginPBTanda15glassfiberfilledPBTcomposite,andaplatecavitywitharibacrosscenterwasused.Variousprocessingvariableswereexaminedintermsoftheirinfluenceonthelengthofwaterpenetrationinmoldedparts,andmechanicalpropertytestswereperformedontheseparts.XraydiffractionXRDwasalsousedtoidentifythematerialandstructuralparameters.Finally,acomparisonwasmadebetweenwaterassistedandgasassistedinjectionmoldedparts.Itwasfoundthatthemeltfillpressure,melttemperature,andshortshotsizewerethedominantparametersaffectingwaterpenetrationbehavior.Materialatthemoldsideexhibitedahigherdegreeofcrystallinitythanthatatthewaterside.Partsmoldedbygasalsoshowedahigherdegreeofcrystallinitythanthosemoldedbywater.Furthermore,theglassfibersnearthesurfaceofmoldedpartswerefoundtobeorientedmostlyintheflowdirection,butorientedsubstantiallymoreperpendiculartotheflowdirectionwithincreasingdistancefromtheskinsurface.C2112006ElsevierLtd.Allrightsreserved.KeywordsWaterassistedinjectionmoldingGlassfiberreinforcedpolybutyleneterephthalatePBTcompositesProcessingparametersB.MechanicalpropertiesCrystallinityA.PolymermatrixcompositesProcessingAnexperimentalstudyofthewaterassistedglassfiberfilledpolybutyleneterephthalateShihJungLiu,MingJenPolymerRheologyandProcessingLab,DepartmentofMechanicalReceived12September2005receivedinrevisedAvailableonline02663538/seefrontmatterC2112006ElsevierLtd.Allrightsreserved.doi10.1016/j.compscitech.2006.09.016injectionmoldingofPBTcompositesLin,YiChuanWuEngineering,ChangGungUniversity,TaoYuan333,Taiwan29June2006accepted11September20062006www.elsevier.com/locate/compscitech6720071415–1424SCIENCEANDTECHNOLOGYTable2AcomparisonofwaterandgasassistedinjectionmoldingWaterGas1.CycletimeShortLong2.MediumcostLowHigh3.InternalfoamingNoYes4.ResidualwallthicknessSmallLarge5.OutsidesurfaceroughnessLowHigh6.OutsidesurfaceglossHighLow1416S.J.Liuetal./CompositesScienceandTechnology6720071415–1424Waterassistedinjectionmoldinghasadvantagesoveritsbetterknowncompetitorprocess,gasassistedinjectionmolding5,becauseitincorporatesashortercycletimetosuccessfullymoldapartduetothehighercoolingcapacFig.1.Schematicdiagramofwaterassistedinjectionmoldingprocess.ityofwaterduringthemoldingprocess.Theincompressibility,lowcost,andeaseofrecyclingthewatermakesitanidealmediumfortheprocess.Sincewaterdoesnotdissolveanddiffuseintothepolymermeltsduringthemoldingprocess,theinternalfoamingphenomenon6thatusuallyoccursingasassistedinjectionmoldedpartscanbeeliminated.Inaddition,waterassistedinjectionmoldingprovidesabettercapabilityofmoldinglargerpartswithasmallresidualwallthickness.Table2listsacomparisonofwaterandgasassistedinjectionmolding.Withincreasingdemandsformaterialswithimprovedperformance,whichmaybecharacterizedbythecriteriaoflowerweight,higherstrength,andafasterandcheaperproductioncycletime,theengineeringofplasticsisaprocessthatcannotbeignored.Theseplasticsincludethermoplasticandthermosetpolymers.Ingeneral,thermoplasticpolymershaveanadvantageoverthermosetpolymersinTable1AdvantagesanddisadvantagesofwaterassistedinjectionmoldingAdvantagesDisadvanta1.Shortcycletime2.Lowassistingmediumcostwaterismuchcheaperandcanbeeasilyrecycled3.Nointernalfoamingphenomenoninmoldedparts1.2.3.4.termsofhigherimpactstrength,fractureresistanceandstrainstofailure.Thismakesthermoplasticpolymersverypopularmaterialsinstructuralapplications.PolybutyleneterephthalatePBTisoneofthemostfrequentlyusedengineeringthermoplasticmaterials,whichisformedbypolymerizing1.4butyleneglycolandDMTtogether.Fiberreinforcedcompositematerialshavebeenadaptedtoimprovethemechanicalpropertiesofneatplasticmaterials.Today,shortglassfiberreinforcedPBTiswidelyusedinelectronic,communicationandautomobileapplications.Therefore,theinvestigationoftheprocessingoffiberreinforcedPBTisbecomingincreasinglyimportant7–10.ThisreportwasmadetoexperimentallystudythewaterassistedinjectionmoldingprocessofpolybutyleneterephthalatePBTmaterials.Experimentswerecarriedoutonan80toninjectionmoldingmachineequippedwithalabscalewaterinjectionsystem,whichincludedawaterpump,apressureaccumulator,awaterinjectionpin,awatertankequippedwithatemperatureregulator,andacontrolcircuit.ThematerialsincludedavirginPBTanda15glassfiberfilledPBTcomposite,andaplatecavity7.FingeringGreaterLess8.AsymmetricalpenetrationMorestableUnstable9.MaterialcrystallinityLowHigh10.ParttransparencyHighLow11.InternalsurfacesemicrystallinematerialsSmoothLesssmooth12.InternalsurfaceamorphousmaterialsRoughSmoothwitharibacrosscenterwasused.Variousprocessingvariableswereexaminedintermsoftheirinfluenceonthelengthofwaterpenetrationinmoldedparts,whichincludedmelttemperature,moldtemperature,meltfillingspeed,shortshotsize,waterpressure,watertemperature,waterholdandwaterinjectiondelaytime.Mechanicalpropertytestswerealsoperformedonthesemoldedparts,andXRDwasusedtoidentifythematerialandstructuralgesCorrosionofthesteelmoldduetowaterLargerorificesfortheinjectionpinrequiredeasiertogetstuckbythepolymermeltSomematerialsaremoredifficulttomoldespeciallyamorphousthermoplasticsRemovalofwateraftermoldingisrequiredparameters.Finally,acomparisonwasmadebetweenwaterassistedandgasassistedinjectionmoldedparts.2.Experimentalprocedure2.1.MaterialsThematerialsusedincludedavirginPBTGrade1111FB,NanYaPlastic,Taiwananda15glassfiberfilledPBTcompositeGrade1210G3,NanYaPlastic,Taiwan.Table3liststhecharacteristicsofthecompositematerials.polymermelt.Table4liststheseprocessingvariablesaswellasthevaluesusedintheexperiments.2.4.GasinjectionunitInordertomakeacomparisonofwaterandgasassistedinjectionmoldedparts,acommerciallyavailablegasinjectionunitGasInjectionPPC1000wasusedforthegasassistedinjectionmoldingexperiments.DetailsofthegasinjectionunitsetupcanbefoundintheRefs.11–15.TheprocessingconditionsusedforgasassistedinjectionmoldingwerethesameasthatofwaterassistedinjectionmoldingtermsinboldinTable4,withtheexceptionofgastemperaturewhichwassetat25C176C.2.5.XRDInordertoanalyzethecrystalstructurewithinthewaterassistedinjectionmoldedparts,wideangleXraydiffractionXRDwith2DdetectoranalysesintransmissionmodewereperformedwithCuKaradiationat40kVand40mA.Morespecifically,themeasurementswereperformedonthemoldsideandwatersidelayersofthewaterassistedinjectionmoldedparts,withthe2hanglerangingfrom7C176to40C176.ThesamplesrequiredfortheseanalysesweretakenfromthecenterportionoftheseFig.2.Layoutanddimensionsofmoldcavityunitmm.S.J.Liuetal./CompositesScienceand2.2.WaterinjectionunitAlabscalewaterinjectionunit,whichincludedawaterpump,apressureaccumulator,awaterinjectionpin,awatertankequippedwithatemperatureregulator,andacontrolcircuit,wasusedforallexperiments3.Anorificetypewaterinjectionpinwithtwoorifices0.3mmindiameteronthesideswasusedtomoldtheparts.Duringtheexperiments,thecontrolcircuitofthewaterinjectionunitreceivedasignalfromthemoldingmachineandcontrolledthetimeandpressureoftheinjectedwater.Beforeinjectionintothemoldcavity,thewaterwasstoredinatankwithatemperatureregulatorfor30mintosustainanisothermalwatertemperature.2.3.MoldingmachineandmoldsWaterassistedinjectionmoldingexperimentswereconductedonan80tonconventionalinjectionmoldingmachinewithahighestinjectionrateof109cm3/s.Aplatecavitywithatrapezoidalwaterchannelacrossthecenterwasusedinthisstudy.Fig.2showsthedimensionsofthecavity.Thetemperatureofthemoldwasregulatedbyawatercirculatingmoldtemperaturecontrolunit.Variousprocessingvariableswereexaminedintermsoftheirinfluenceonthelengthofwaterpenetrationinwaterchannelsofmoldedpartsmelttemperature,moldtemperature,meltfillpressure,watertemperatureandpressure,waterinjectiondelaytimeandholdtime,andshortshotsizeoftheTable3Characteristicsoftheglass–fiberreinforcedPBTcompositePropertyASTMPBT15G.F.PBTYieldstrengthkg/cm2D6386001000Bendingstresskg/cm2D5709001500HardnessRscaleD785119120HeatdistortiontemperatureC176C18.6kg/cm2D64860200MeltflowindexMFID12384025ImpactstrengthKgcm/cmD25655MeltingtemperatureC176CDSC224224Technology6720071415–14241417moldedparts.ToobtainthedesiredthicknessfortheXRDsamples,theexcesswasremovedbypolishingthesamplesonarotatingwheelonarotatingwheel,firstwithwetsiliconcarbidepapers,thenwith300gradesiliconcarbidepaper,followedby600and1200gradepaperforabettersurfacesmoothness.2.6.MechanicalpropertiesTensilestrengthandbendingstrengthweremeasuredonatensiletester.TensiletestswereperformedonspecimensobtainedfromthewaterassistedinjectionmoldedpartsseeFig.3toevaluatetheeffectofwatertemperatureon20mm10mm1mm.BendingtestswereperformedinamicrotensiletesteraccordingtotheASTMD256test.A200Nloadcellwasusedandthecrossheadspeedwas50mm/min.2.7.MicroscopicobservationThefiberorientationinmoldedspecimenswasobservedunderascanningelectronmicroscopeJeolModel5410.SpecimensforobservationwerecutfrompartsmoldedbywaterassistedinjectionmoldingacrossthethicknessTable4TheprocessingvariablesaswellasthevaluesusedintheexperimentsABCDEFMeltpressureMpaMelttemperatureC176CShortshotsizeWaterpressureMpaWatertemperatureC176CMoldtemperatureC176C140280270768808012627526577975751142702607810707098265255801165658426025081126060ThevaluesintheparenthesesarethemelttemperaturesusedforvirginPBTmaterials.1418S.J.Liuetal./CompositesScienceandTechnology6720071415–1424thetensileproperties.Thedimensionsofspecimensfortheexperimentswere30mm10mm1mm.TensiletestswereperformedinaLLOYDtensiometeraccordingtotheASTMD638Mtest.A2.5kNloadcellwasusedandthecrossheadspeedwas50mm/min.Bendingtestswerealsoperformedatroomtemperatureonwaterassistedinjectionmoldedparts.ThebendingspecimenswereobtainedwithadiecutterfrompartsFig.3subjectedtovariouswatertemperatures.ThedimensionsofthespecimenswereFig.3.Schematically,thepositioningofthesamplescutfromthemoldedFig.3.Theywereobservedonthecrosssectionperpendiculartotheflowdirection.Allspecimensurfacesweregoldsputteredbeforeobservation.3.ResultsanddiscussionAllexperimentswereconductedonan80tonconventionalinjectionmoldingmachine,withahighestinjectionrateof109cm3/s.Aplatecavitywithatrapezoidalwaterchannelacrossthecenterwasusedforallexperiments.partsfortensileandbendingtestsandmicroscopicobservations.

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