ASTM_D570_2005-吸水率测试

吸水率测试

D

ISO62istechnicallyequivalenttothistestmethod.

2.ReferencedDocuments2.1ASTMStandards:

D647PracticeforDesignofMoldsforTestSpecimensofPlasticMoldingMaterials22.2ISOStandard:

ISO62Plastics—DeterminationofWaterAbsorption33.Signi canceandUse

3.1Thistestmethodforrateofwaterabsorptionhastwochieffunctions: rst,asaguidetotheproportionofwaterabsorbedbyamaterialandconsequently,inthosecaseswheretherelationshipsbetweenmoistureandelectricalormechanicalproperties,dimensions,orappearancehavebeendetermined,asaguidetotheeffectsofexposuretowaterorhumidconditionsonsuchproperties;andsecond,asacontroltestontheuniformityofaproduct.Thissecondfunctionisparticu-larlyapplicabletosheet,rod,andtubearmswhenthetestismadeonthe nishedproduct.

3.2Comparisonofwaterabsorptionvaluesofvariousplas-ticscanbemadeonthebasisofvaluesobtainedinaccordancewith7.1and7.4.

3.3Idealdiffusionofliquids4intopolymersisafunctionofthesquarerootofimmersiontime.Timetosaturationisstronglydependentonspecimenthickness.Forexample,Table1showsthetimetoapproximatetimesaturationforvariousthicknessofnylon-6.

3.4Themoisturecontentofaplasticisveryintimatelyrelatedtosuchpropertiesaselectricalinsulationresistance,dielectriclosses,mechanicalstrength,appearance,anddimen-sions.Theeffectuponthesepropertiesofchangeinmoisturecontentduetowaterabsorptiondependslargelyonthetypeofexposure(byimmersioninwaterorbyexposuretohighhumidity),shapeofthepart,andinherentpropertiesoftheplastic.Withnonhomogeneousmaterials,suchaslaminatedforms,therateofwaterabsorptionmaybewidelydifferentthrougheachedgeandsurface.Evenforotherwisehomoge-neousmaterials,itmaybeslightlygreaterthroughcutedgesthanthroughmoldedsurfaces.Consequently,attemptstocorrelatewaterabsorptionwiththesurfaceareamustgenerallybelimitedtocloselyrelatedmaterialsandtosimilarlyshapedspecimens:Formaterialsofwidelyvaryingdensity,relationbetweenwater-absorptionvaluesonavolumeaswellasaweightbasismayneedtobeconsidered.

4.Apparatus

4.1Balance—Ananalyticalbalancecapableofreading0.0001g.

4.2Oven,capableofmaintaininguniformtemperaturesof5063°C[12265.4°F]andof105to110°C[221to230°F].5.TestSpecimen

5.1Thetestspecimenformoldedplasticsshallbeintheformofadisk50.8mm[2in.]indiameterand3.2mm[1 8in.]inthickness(seeNote2).Permissiblevariationsinthicknessare60.18mm[60.007in.]forhot-moldedand60.30mm[60.012in.]forcold-moldedorcastmaterials.

ThistestmethodisunderthejurisdictionofASTMCommitteeD20onPlasticsandisthedirectresponsibilityofSubcommitteeD20.50onDurabilityofPlastics.CurrenteditionapprovedNov.1,http://www.77cn.com.cnstpreviouseditionapprovedin1998asD570-98.2

Withdrawn.3

AvailablefromAmericanNationalStandardsInstitute(ANSI),25W.43rdSt.,4thFloor,NewYork,NY10036.

1

Additionalinformationregardingdiffusionofliquidsinpolymerscanbefoundinthefollowingreferences:(1)Diffusion,MassTransferinFluidSystems,E.L.Cussler,CambridgeUniversityPress,1985,ISBN0-521-29846-6,(2)DiffusioninPolymers,J.CrankandG.S.Park,AcademicPress,1968,and(3)“Permeation,Diffusion,andSorptionofGasesandVapors,”R.M.FelderandG.S.Huvard,inMethodsofExperimentalPhysics,Vol16C,1980,AcademicPress.

4

Copyright©ASTMInternational,100BarrHarborDrive,POBoxC700,WestConshohocken,PA19428-2959,UnitedStates.

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吸水率测试

TABLE1TimetoSaturationforVariousThicknessofNylon-6

Thickness,mm

123.21025

TypicalTimeto95%Saturation,h

10040010001000062

000

borhoodof110°C[230°F],shallbedriedinanovenfor24hat5063°C[12265.4°F],cooledinadesiccator,andimme-diatelyweighedtothenearest0.001g.

NOTE4—Ifastaticchargeinterfereswiththeweighing,lightlyrubthesurfaceofthespecimenswithagroundedconductor.

NOTE2—ThediskmoldprescribedintheMoldsforDiskTestSpecimensSectionofPracticeD647issuitableformoldingdisktestspecimensofthermosettingmaterialsbutnotthermoplasticmaterials.

5.2ISOStandardSpecimen—Thetestspecimenforhomo-geneousplasticsshallbe60by60by1mm.Toleranceforthe60-mmdimensionis62mmand60.05mmforthe1-mmthickness.ThistestmethodandISO62aretechnicallyequiva-lentwhenthetestspecimendescribedin5.2isused.

5.3Thetestspecimenforsheetsshallbeintheformofabar76.2mm[3in.]longby25.4mm[1in.]widebythethicknessofthematerial.Whencomparisonofabsorptionvalueswithmoldedplasticsisdesired,specimens3.2-mm[1 8-in.]thickshouldbeused.Permissiblevariationsinthicknessshallbe0.20mm[60.008in.]exceptformaterialswhichhavegreaterstandardcommercialtolerances.

5.4Thetestspecimenforrodsshallbe25.4-mm[1-in.]longforrods25.4mmindiameterorunderand12.7-mm[1 2-in.]longforlarger-diameterrods.Thediameterofthespecimenshallbethediameterofthe nishedrod.

5.5Thetestspecimenfortubeslessthan76mm[3in.]ininsidediametershallbethefullsectionofthetubeand25.4-mm[1-in.]long.Fortubes76mm[3in.]ormoreininsidediameter,arectangularspecimenshallbecut76mminlengthinthecircumferentialdirectionofthetubeand25.4mminwidthlengthwiseofthetube.

5.6Thetestspecimensforsheets,rods,andtubesshallbemachined,sawed,orshearedfromthesamplesoastohavesmoothedgesfreefromcracks.Thecutedgesshallbemadesmoothby nishingwithNo.0or nersandpaperoremerycloth.Sawing,machining,andsandpaperingoperationsshallbeslowenoughsothatthematerialisnotheatedappreciably.

NOTE3—Ifthereisanyoilonthesurfaceofthespecimenwhenreceivedorasaresultofmachiningoperations,washthespecimenwithaclothwetwithgasolinetoremoveoil,wipewithadrycloth,andallowtostandinairfor2htopermitevaporationofthegasoline.Ifgasolineattackstheplastic,usesomesuitablesolventordetergentthatwillevaporatewithinthe2-hperiod.

6.1.2Specimensofmaterials,suchasphenoliclaminatedplasticsandotherproductswhosewater-absorptionvaluehasbeenshownnottobeappreciablyaffectedbytemperaturesupto110°C[230°F],shallbedriedinanovenfor1hat105to110°C[221to230°F].

6.1.3Whendataforcomparisonwithabsorptionvaluesforotherplasticsaredesired,thespecimensshallbedriedinanovenfor24hat506 …… 此处隐藏：10869字，全部文档内容请下载后查看。喜欢就下载吧 ……