附錄附錄1Anexperimentalstudyofthewater-assistedinjectionmoldingofglassfiberfilledpoly-butylene-terephthalate(PBT)compositesAbstract：Thepurposeofthisreportwastoexperimentallystudythewater-assistedinjectionmoldingprocessofpoly-butylene-terephthalate(PBT)composites.Experimentswerecarriedoutonan80-toninjection-moldingmachineequippedwithalabscalewaterinjectionsystem,whichincludedawaterpump,apressureaccumulator,awaterinjectionpin,awatertankequippedwithatemperatureregulator,andacontrolcircuit.ThematerialsincludedvirginPBTanda15%glassfiberfilledPBTcomposite,andaplatecavitywitharibacrosscenterwasused.Variousprocessingvariableswereexaminedintermsoftheirinfluenceonthelengthofwaterpenetrationinmoldedparts,andmechanicalpropertytestswereperformedontheseparts.X-raydiffraction(XRD)wasalsousedtoidentifythematerialandstructuralparameters.Finally,acomparisonwasmadebetweenwater-assistedandgas-assistedinjectionmoldedparts.Itwasfoundthatthemeltfillpressure,melttemperature,andshortshotsizewerethedominantparametersaffectingwaterpenetrationbehavior.Materialatthemold-sideexhibitedahigherdegreeofcrystallinitythanthatatthewater-side.Partsmoldedbygasalsoshowedahigherdegreeofcrystallinitythanthosemoldedbywater.Furthermore,theglassfibersnearthesurfaceofmoldedpartswerefoundtobeorientedmostlyintheflowdirection,butorientedsubstantiallymoreperpendiculartotheflowdirectionwithincreasingdistancefromtheskinsurface.Keywords:Waterassistedinjectionmolding；Glassfiberreinforcedpoly-butylene-terephthalate(PBT)composites；Processingparameters；B.Mechanicalproperties；Crystallinity；A.Polymermatrixcomposites；1.IntroductionWater-assistedinjectionmoldingtechnology1hasproveditselfabreakthroughinthemanufactureofplasticpartsduetoitslightweight,fastercycletime,andrelativelylowerresincostperpart.Inthewater-assistedinjectionmoldingprocess,themoldcavityispartiallyfilledwiththepolymermeltfollowedbytheinjectionofwaterintothecoreofthepolymermelt.Aschematicdiagramofthewater-assistedinjectionmoldingprocessisillustratedinFig.1.Water-assistedinjectionmoldingcanproducepartsincorporatingboththickandthinsectionswithlessshrink-ageandwarpageandwithabettersurfacefinish,butwithashortercycletime.Thewater-assistedinjectionmoldingprocesscanalsoenablegreaterfreedomofdesign,materialsavings,weightreduction,andcostsavingsintermsoftoolingandpresscapacityrequirements24.Typicalapplicationsincluderodsandtubes,andlargesheet-likestructuralpartswithabuilt-inwaterchannelnetwork.Ontheotherhand,despitetheadvantagesassociatedwiththeprocess,themoldingwindowandprocesscontrolaremorecriticalanddifficultsinceadditionalprocessingparametersareinvolved.Watermayalsocorrodethesteelmold,andsomematerialsincludingthermoplasticcompositesaredifficulttomoldsuccessfully.Theremovalofwateraftermoldingisalsoachallengeforthisnoveltechnology.Table1liststheadvantagesandlimitationsofwater-assistedinjectionmoldingtechnology.Fig.1.Schematicdiagramofwater-assistedinjectionmoldingprocess.Waterassistedinjectionmoldinghasadvantagesoveritsbetterknowncompetitorprocess,gasassistedinjectionmolding5,becauseitincorporatesashortercycletimetosuccessfullymoldapartduetothehighercoolingcapacityofwaterduringthemoldingprocess.Theincompressibility,lowcost,andeaseofrecyclingthewatermakesitanidealmediumfortheprocess.Sincewaterdoesnotdissolveanddiffuseintothepolymermeltsduringthemoldingprocess,theinternalfoamingphenomenon6thatusuallyoccursingas-assistedinjectionmoldedpartscanbeeliminated.Inaddition,waterassistedinjectionmoldingprovidesabettercapabilityofmoldinglargerpartswithasmallresidualwallthickness.Table2listsacomparisonofwaterandgasassistedinjectionmolding.Withincreasingdemandsformaterialswithimprovedperformance,whichmaybecharacterizedbythecriteriaoflowerweight,higherstrength,andafasterandcheaperproductioncycletime,theengineeringofplasticsisaprocessthatcannotbeignored.Theseplasticsincludethermoplasticandthermosetpolymers.Ingeneral,thermoplasticpolymershaveanadvantageoverthermosetpolymersinpopularmaterialsinstructuralapplications.Poly-butylene-terephthalate(PBT)isoneofthemostfrequentlyusedengineeringthermoplasticmaterials,whichisformedbypolymerizing1.4butyleneglycolandDMTtogether.Fiber-reinforcedcompositematerialshavebeenadaptedtoimprovethemechanicalpropertiesofneatplasticmaterials.Today,shortglassfiberreinforcedPBTiswidelyusedinelectronic,communicationandautomobileapplications.Therefore,theinvestigationoftheprocessingoffiber-reinforcedPBTisbecomingincreasinglyimportant710.Thisreportwasmadetoexperimentallystudythewaterassistedinjectionmoldingprocessofpoly-butylene-terephthalate(PBT)materials.Experimentswerecarriedoutonan80-toninjection-moldingmachineequippedwithalabscalewaterinjectionsystem,whichincludedawaterpump,apressureaccumulator,awaterinjectionpin,awatertankequippedwithatemperatureregulator,andacontrolcircuit.ThematerialsincludedavirginPBTanda15%glassfiberfilledPBTcomposite,andaplatecavitywitharibacrosscenterwasused.Variousprocessingvariableswereexaminedintermsoftheirinfluenceonthelengthofwaterpenetrationinmoldedparts,whichincludedmelttemperature,moldtemperature,meltfillingspeed,short-shotsize,waterpressure,watertemperature,waterholdandwaterinjectiondelaytime.Mechanicalpropertytestswerealsoperformedonthesemoldedparts,andXRDwasusedtoidentifythematerialandstructuralparameters.Finally,acomparisonwasmadebetweenwater-assistedandgas-assistedinjectionmoldedparts.Table1Advantagesanddisadvantagesofwater-assistedinjectionmoldingAdvantagesDisadvantages1.Shortcycletime1.Corrosionofthesteelmoldduetowater2.Lowassistingmediumcost(waterismuchcheaperandcanbeeasilyrecycled)2.Largerorificesfortheinjectionpinrequired(easiertogetstuckbythepolymermelt)3.Nointernalfoamingphenomenoninmoldedparts3.Somematerialsaremoredifficulttomold(especiallyamorphousthermoplastics)4.Removalofwateraftermoldingisrequired2.Experimentalprocedure2.1.MaterialsThematerialsusedincludedavirginPBT(Grade1111FB,Nan-YaPlastic,Taiwan)anda15%glassfiberfilledPBTcomposite(Grade1210G3,Nan-YaPlastic,Taiwan).Table3liststhecharacteristicsofthecompositematerials.2.2.WaterinjectionunitAlabscalewaterinjectionunit,whichincludedawaterpump,apressureaccumulator,awaterinjectionpin,awatertankequippedwithatemperatureregulator,andacontrolcircuit,wasusedforallexperiments3.Anorifice-typewaterinjectionpinwithtwoorifices(0.3mmindiameter)onthesideswasusedtomoldtheparts.Duringtheexperiments,thecontrolcircuitofthewaterinjectionunitreceivedasignalfromthemoldingmachineandcontrolledthetimeandpressureoftheinjectedwater.Beforeinjectionintothemoldcavity,thewaterwasstoredinatankwithatemperatureregulatorfor30mintosustainanisothermalwatertemperature.2.3.MoldingmachineandmoldsWater-assistedinjectionmoldingexperimentswereconductedonan80-tonconventionalinjection-moldingmachinewithahighestinjectionrateof109cm3/s.Aplatecavitywithatrapezoidalwaterchannelacrossthecenterwasusedinthisstudy.Fig.2showsthedimensionsofthecavity.Thetemperatureofthemoldwasregulatedbyawater-circulatingmoldtemperaturecontrolunit.Variousprocessingvariableswereexaminedintermsoftheirinfluenceonthelengthofwaterpenetrationinwaterchannelsofmoldedparts:melttemperature,moldtemperature,meltfillpressure,watertemperatureandpressure,waterinjectiondelaytimeandholdtime,andshortshotsizeofthepolymermelt.Table4liststheseprocessingvariablesaswellasthevaluesusedintheexperiments.2.4.GasinjectionunitInordertomakeacomparisonofwaterandgas-assistedinjectionmoldedparts,acommerciallyavailablegasinjectionunit(GasInjectionPPC-1000)wasusedforthegasassistedinjectionmoldingexperiments.DetailsofthegasinjectionunitsetupcanbefoundintheRefs.1115.Theprocessingconditionsusedforgas-assistedinjectionmoldingwerethesameasthatofwater-assistedinjectionmolding(termsinboldinTable4),withtheexceptionofgastemperaturewhichwassetat25C.2.5.XRDInordertoanalyzethecrystalstructurewithinthewater-assistedinjection-moldedparts,wide-angleX-raydiffraction(XRD)with2DdetectoranalysesintransmissionmodewereperformedwithCuKaradiationat40kVand40mA.Morespecificall