ASTM D792-13 用位移法测定塑料密度和比重的标准试验方法

Designation:D792−13StandardTestMethodsforDensityandSpecificGravity(RelativeDensity)ofPlasticsbyDisplacement1ThisstandardisissuedunderthefixeddesignationD792;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheDepartmentofDefense.1.Scope*1.1Thesetestmethodsdescribethedeterminationofthespecificgravity(relativedensity)anddensityofsolidplasticsinformssuchassheets,rods,tubes,ormoldeditems.1.2Twotestmethodsaredescribed:1.2.1TestMethodA—Fortestingsolidplasticsinwater,and1.2.2TestMethodB—Fortestingsolidplasticsinliquidsotherthanwater.1.3ThevaluesstatedinSIunitsaretoberegardedasthestandard.1.4Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.NOTE1—ThisstandardisnotequivalenttoISO1183–1MethodA.Thistestmethodprovidesmoreguidelinesonsampleweightanddimension.ISO1183-1allowstestingatanadditionaltemperatureof2762°C.2.ReferencedDocuments2.1ASTMStandards:2D618PracticeforConditioningPlasticsforTestingD891TestMethodsforSpecificGravity,Apparent,ofLiquidIndustrialChemicalsD4968GuideforAnnualReviewofTestMethodsandSpecificationsforPlasticsD6436GuideforReportingPropertiesforPlasticsandThermoplasticElastomersE1SpecificationforASTMLiquid-in-GlassThermometersE12TerminologyRelatingtoDensityandSpecificGravityofSolids,Liquids,andGases(Withdrawn1996)3E691PracticeforConductinganInterlaboratoryStudytoDeterminethePrecisionofaTestMethodIEEE/ASTMSI-10PracticeforUseoftheInternationalSystemofUnits(SI)(theModernizedMetricSystem)3.Terminology3.1General—Theunits,symbols,andabbreviationsusedinthesetestmethodsareinaccordancewithIEEE/ASTMSI-10.3.2Definitions:3.2.1specificgravity(relativedensity)—theratioofthemassofagivenvolumeoftheimpermeableportionofthematerialat23°Ctothemassofanequalvolumeofgas-freedistilledorde-mineralizedwateratthesametemperature;theformofexpressionshallbe:Specificgravity~relativedensity!23/23°C~orspgr23/23°C!NOTE2—ThisdefinitionisessentiallyequivalenttothedefinitionforapparentspecificgravityandapparentdensityinTerminologyE12,becausethesmallpercentagedifferenceintroducedbynotcorrectingforthebuoyancyofairisinsignificantformostpurposes.3.2.2density—cubicmetreofimpermeableportionofthematerialat23°C.Theformofexpressionshallbe:D23,kg/m3NOTE3—TheSIunitofdensity,asdefinedinIEEE/ASTMSI-10,iskg/m3.Toconvertdensitying/cm3todensityinkg/m3,multiplyby1000.NOTE4—Toconvertspecificgravity23/23°Ctodensity23°C,kg/m3,usethefollowingequation:D23C,kg/m35spgr23/23°C3997.5Where997.5kg/m3isthedensityofwaterat23°C.4.SummaryofTestMethod4.1Determinethemassofaspecimenofthesolidplasticinair.Itisthenimmersedinaliquid,itsapparentmassuponimmersionisdetermined,anditsspecificgravity(relativedensity)calculated.1ThesetestmethodsareunderthejurisdictionofASTMCommitteeD20onPlasticsandarethedirectresponsibilityofSubcommitteeD20.70onAnalyticalMethods(SectionD20.70.01).CurrenteditionapprovedNov.1,2013.PublishedNovember2013.Originallyapprovedin1944.Lastpreviouseditionapprovedin2008asD792-08.DOI:10.1520/D0792-13.2ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.ForAnnualBookofASTMStandardsvolumeinformation,refertothestandard’sDocumentSummarypageontheASTMwebsite.3Thelastapprovedversionofthishistoricalstandardisreferencedonwww.astm.org.*ASummaryofChangessectionappearsattheendofthisstandardCopyright©ASTMInternational,100BarrHarborDrive,POBoxC700,WestConshohocken,PA19428-2959.UnitedStates1CopyrightASTMInternational--``,`````,``,``,`,,`,,```````,,-`-`,,`,,`,`,,`---5.SignificanceandUse5.1Thespecificgravityordensityofasolidisapropertythatisconvenientlymeasuredtoidentifyamaterial,tofollowphysicalchangesinasample,toindicatedegreeofuniformityamongdifferentsamplingunitsorspecimens,ortoindicatetheaveragedensityofalargeitem.5.2Changesindensityofasinglematerialareduetolocalizeddifferencesincrystallinity,lossofplasticizer,absorp-tionofsolvent,ortoothercauses.Itispossiblethatportionsofasampledifferindensitybecauseoftheirdifferencesincrystallinity,thermalhistory,porosity,andcomposition(typesorproportionsofresin,plasticizer,pigment,orfiller).5.3Densityisusefulforcalculatingstrength-weightandcost-weightratios.6.Sampling6.1Thesamplingunitsusedforthedeterminationofspe-cificgravity(relativedensity)shallberepresentativeofthequantityofproductforwhichthedataarerequired.6.1.1Ifitisknownorsuspectedthatthesampleconsistsoftwoormorelayersorsectionshavingdifferentspecificgravities,eithercompletefinishedpartsorcompletecrosssectionsofthepartsorshapesshallbeusedasthespecimens,orseparatespecimensshallbetakenandtestedfromeachlayer.Thespecificgravity(relativedensity)ofthetotalpartshallnotbeobtainedbyaddingthespecificgravityofthelayers,unlessrelativepercentagesofthelayersaretakenintoaccount.7.Conditioning7.1Conditioning—Conditionthetestspecimensat2362°Cand50610%relativehumidityfornotlessthan40hpriortotestinaccordancewithProcedureAofPracticeD618,unlessotherwisespecifiedbythecontractorrelevantmaterialspecifications.Incasesofdisagreement,thetolerancesshallbe61°Cand65%relativehumidity.7.2TestConditions—Conducttestsinthestandardlabora-toryatmosphereof2362°Cand50610%relativehumidity,unlessotherwisespecifiedinthisspecificationorbythecontractorrelevantmaterialspecification.Incasesofdisagreement,thetolerancesshallbe61°Cand65%relativehumidity.TESTMETHODAFORTESTINGSOLIDPLASTICSINWATER(SPECIMENS1TO50g)8.Scope8.1Thistestmethodinvolvesweighingaone-piecespeci-menof1to50ginwater,usingasinkerwithplasticsthatarelighterthanwater.Thistestmethodissuitableforplasticsthatarewetby,butotherwisenotaffectedbywater.9.Apparatus9.1AnalyticalBalance—Abalancewithaprecisionof0.1mgorbetterisrequiredformaterialshavingdensitieslessthan1.00g/cm3andsampleweightslessthan10grams.Forallothermaterialsandsampleweights,abalancewithprecisionof1mgorbetterisacceptable(seeNote5).Thebalanceshallbeequippedwithastationarysupportfortheimmersionvesselabovethebalancepan(“panstraddle”).NOTE5—Thebalanceshallprovidetheprecisionthatallmaterialstestedhavethreesignificantfiguresondensity.Incasethatmaterialswithdifferentdensitiesaretestedononesinglebalance,usethebalancethatprovidesatleastthreesignificantfiguresforallmaterialsconcerned.NOTE6—Toassurethatthebalancemeetstheperformancerequirements,checkonzeropointandsensitivityfrequentlyandperformperiodiccalibration.9.2SampleHolder,corrosion-resistant(forexample,wire,gemholder,etc.).9.3Sinker—Asinkerforusewithspecimensofplasticsthathavespecificgravitieslessthan1.00.Thesinkershall:(1)becorrosion-resistant;(2)haveaspecificgravityofnotlessthan7.0;(3)havesmoothsurfacesandaregularshape;and(4)beslightlyheavierthannecessarytosinkthespecimen.Thesinkershallhaveanopeningtofacilitateattachmenttothespecimenandsampleholder.9.4ImmersionVessel—Abeakerorotherwide-mouthedvesselforholdingthewaterandimmersedspecimen.9.5Thermometer—Athermometerreadableto0.1°Corbetter.10.Materials10.1Water—Thewatershallbesubstantiallyair-freeanddistilledorde-mineralizedwater.NOTE7—Airinwatercanberemovedbyboilingandcoolingthewater,orbyshakingthewaterundervacuuminaheavy-walledvacuumflask.(Warning—Useglovesandshielding.)Ifthewaterdoesnotwetthespecimen,addafewdropsofawettingagentintothewater.Ifthissolutiondoesnotwetthespecimen,MethodBshallbeused.11.TestSpecimen11.1Thetestspecimenshallbeasinglepieceofmaterialwithasizeandshapesuitableforthetestingapparatus,providedthatitsvolumeshallbenotlessthan1cm3anditssurfaceandedgesshallbemadesmooth.Thethicknessofthespecimenshallbeatleast1mmforeach1gofweight.Aspecimenweighing1to5gwasfoundtobeconvenient,butspecimensuptoapproximately50garealsoacceptable(seeNote8).Careshallbetakenincuttingspecimenstoavoidchangesindensityresultingfromcompressivestressesorfrictionalheating.NOTE8—Specificationsforcertainplasticsrequireaparticularmethodofspecimenpreparationandshouldbeconsultedifapplicable.11.2Thespecimenshallbefreefromoil,grease,andotherforeignmatter.12.Procedure12.1Measureandrecordthewatertemperature.12.2Weighthespecimeninair.Weightothenearest0.1mgforspecimensofmass1to10ganddensitylessthan1.00g/cm3.Weightothenearest1mgforotherspecimens.12.3Ifnecessary,attachtothebalanceapieceoffinewiresufficientlylongtoreachfromthehookabovethepantothesupportfortheimmersionvessel.InthiscaseattachtheD792−132CopyrightASTMInternational--``,`````,``,``,`,,`,,```````,,-`-`,,`,,`,`,,`---specimentothewiresuchthatitissuspendedabout25mmabovethevesselsupport.NOTE9—Ifawireisused,weighthespecimeninairafterhangingfromthewire.Inthiscase,recordthemassofthespecimen,a=(massofspecimen+wire,inair)−(massofwireinair).12.4Mounttheimmersionvesselonthesupport,andcompletelyimmersethesuspendedspecimen(andsinkers,ifused)inwater(see10.1)atatemperatureof2362°C.Thevesselmustnottouchsampleholderorspecimen.Removeanybubblesadheringtothespecimen,sampleholder,orsinker,byrubbingthemwithawire.Payparticularattentiontoholesinthespecimenandsinker.Ifthebubblesarenotremovedbythismethodorifbubblesarecontinuouslyformed(asfromdissolvedgases),theuseofvacuumisrecommended(seeNote10).Determinethemassofthesuspendedspecimentotherequiredprecision(see12.2)(seeNote11).Recordthisapparentmassasb(themassofthespecimen,sinker,ifused,andthepartiallyimmersedwireinliquid).Unlessotherwisespecified,weighrapidlyinordertominimizeabsorptionofwaterbythespecimen.NOTE10—Somespecimensmaycontainabsorbedordissolvedgases,orirregularitieswhichtendtotrapairbubbles;anyofthesemayaffectthedensityvaluesobtained.Insuchcases,theimmersedspecimenmaybesubjectedtovacuuminaseparatevesseluntilevolutionofbubbleshassubstantiallyceasedbeforeweighing(seeTestMethodB).Itmustalsobedemonstratedthattheuseofthistechniqueleadstoresultsoftherequireddegreeofprecision.NOTE11—Itmaybenecessarytochangethesensitivityadjustmentofthebalancetoovercomethedampingeffectoftheimmersedspecimen.12.5Weighthesampleholder(andsinker,ifused)inwaterwithimmersiontothesamedepthasusedinthepreviousstep(Notes12and13).Recordthisweightasw(massofthesampleholderinliquid).NOTE12—Ifawireisused,itisconvenienttomarkthelevelofimmersionbymeansofashallownotchfiledinthewire.Thefinerthewire,thegreaterthetoleranceispermittedinadjustingthelevelofimmersionbetweenweighings.WithwireAwgNo.36orfiner,disregarditsdegreesofimmersionand,ifnosinkerisused,usethemassofthewireinairasw.NOTE13—Ifthewireisusedandisleftattachedtothebalancearmduringaseriesofdeterminations,determinethemassawiththeaidofatareontheotherarmofthebalanceorasinNote9.Insuchcases,caremustbetakenthatthechangeofmassofthewire(forexample,fromvisiblewater)betweenreadingsdoesnotexceedthedesiredprecision.12.6Repeattheprocedurefortherequirednumberofspecimens.Twospecimenspersamplearerecommended.DetermineacceptabilityofnumberofreplicatetestspecimensbycomparingresultswithprecisiondatagiveninTables1and2.Useadditionalspecimensifdesired.13.Calculation13.1Calculatethespecificgravityoftheplasticasfollows:spgr23/23°C5a/~a1w2b!where:a=apparentmassofspecimen,withoutwireorsinker,inair,b=apparentmassofspecimen(andofsinker,ifused)completelyimmersedandofthewirepartiallyimmersedinliquid,andw=apparentmassoftotallyimmersedsinker(ifused)andofpartiallyimmersedwire.13.2Calculatethedensityoftheplasticasfollows:D23C,kg/m35spgr23/23°C3997.513.3Ifthetemperatureofthewaterisdifferentthan23°C,usethedensityofwaterlistedinTable3directly,orusethefollowingequationstocalculatethedensityofwaterattestingtemperature:M5∆D/∆t(1)D~conversionto23°C!,kg/m3(2)5spgrta/tw3@997.51~tw223!3M#andspgr23/235D~conversionto23°C!/997.5(3)where:M=slope,∆D=differencebetweenthelowestandhighesttemperaturetoleranceforthestandarddensityofwater(D@21°C–D@25°C),∆t=differencebetweenthehighestandlowesttemperaturetolerancerecommended,(21°C–25°C),ta=temperatureofair,andtw=temperatureofwater.14.Report14.1Reportthefollowinginformation:14.1.1Completeidentificationofthematerialorproducttested,includingmethodofspecimenpreparationandconditioning,14.1.2Averagespecificgravity(relativedensity)forallspecimensfromasamplingunitcorrectedto23.0°C(Table3)TABLE1TestMethodASpecificGravityTestedinWaterMaterialMeanSrASRBrCRDPolypropylene0.90070.001960.002970.005550.00841CelluloseAcetateButyrate1.19730.002320.003040.006570.00860PolyphenyleneSulfide1.17080.005400.007380.015280.02089Thermoset1.31360.002710.003130.007670.02171PolyvinylChloride1.33960.002430.006150.006880.01947ASr=withinlaboratorystandarddeviationfortheindividualmaterial.Itisobtainedbypoolingthewithin-laboratorystandarddeviationsofthetestresultsfromalloftheparticipatinglaboratories:Sr=[[(s1)2+(s2)2...+(sn)2]/n]1/2BSR=between-laboratoriesreproducibility,expressedasstandarddeviation:SR=[Sr2+SL2]1/2whereSListhestandarddeviationoflaboratorymeans.Cr=within-laboratorycriticalintervalbetweentwotestresults=2.8×Sr.DR=between-laboratoriescriticalintervalbetweentwotestresults=2.8×SR.D792−133CopyrightASTMInternational--``,`````,``,``,`,,`,,```````,,-`-`,,`,,`,`,,`---arereportedasspgr23/23°C=___,oraveragedensityreportedasD23C=___kg/m3,NOTE14—Reportingdensitying/cm3isalsoacceptableprovidedthatitisagreeduponbytheusers.14.1.3Ameasureofthedegreeofvariationofspecificgravityordensitywithinthesamplingunitsuchasthestandarddeviationandnumberofdeterminationsonahomogeneousmaterialortheaveragesplusthesemeasuresofdispersionondifferentlayersorareasofanonhomogeneousproduct,14.1.4Reportthetemperatureofthewater.14.1.5Reportthedensityandspecificgravitywiththreesignificantfigures.14.1.6Anyevidenceofporosityofthematerialorspecimen,14.1.7Themethodoftest(thatis,MethodAofTestMethodD792),and14.1.8Dateoftest.15.PrecisionandBias15.1SeeSection23.TESTMETHODBFORTESTINGSOLIDPLASTICSINLIQUIDSOTHERTHANWATER(SPECIMENS1TO50g)16.Scope16.1TestMethodBusesaliquidotherthanwaterfortestingone-piecespecimens,1to50g,ofplasticsthatareaffectedbywaterorarelighterthanwater.17.Apparatus17.1Theapparatusshallincludethebalance,wire,andimmersionvesselofSection8,and,optionally,thefollowing:17.2PycnometerwithThermometer—A25-mLspecificgravitybottlewiththermometer,or17.3Pycnometer—ApycnometeroftheWeldtype,prefer-ablywithacapacityofabout25mLandanexternalcapoverthestopper.17.4Thermometer—AthermometerhavingtendivisionsperdegreeCelsiusoveratemperaturerangeofnotlessthan5°Cor10°Faboveandbelowthestandardtemperature,andhavinganicepointforcalibration.Athermometershortenoughtobehandledinsidethebalancecasewillbefoundconvenient.ASTMThermometer23C(seeSpecificationE1)andAnschütz-typethermometershavebeenfoundsatisfactoryforthispurpose.17.5Constant-TemperatureBath—Anappropriateconstant-temperaturebathadjustedtomaintainatemperatureof2360.1°C.18.Materials18.1ImmersionLiquid—Theliquidusedshallnotdissolve,swell,orotherwiseaffectthespecimen,butshallwetitandshallhaveaspecificgravitylessthanthatofthespecimen.Inaddition,theimmersionliquidshallbenon-hygroscopic,hasalowvaporpressure,alowviscosity,andahighflashpoint,andshallleavelittleornowaxyortarryresidueonevaporation.Anarrowcutdistilledfromkerosinemeetstheserequirementsformanyplastics.Thespecificgravity23/23°Coftheimmersionliquidshallbedeterminedshortlybeforeandaftereachuseinthismethodtoaprecisionofatleast0.1%relative,unlessithasbeenestablishedexperimentallyintheparticularapplica-tionthatalesserfrequencyofdeterminationalsoprovidesthedesiredprecision.NOTE15—Forthedeterminationofthespecificgravityoftheliquid,theuseofastandardplummetofknownvolumeorofMethodA,C,orDofTestMethodsD891,usingthemodificationsrequiredtogivespecificgravity23/23°Cinsteadofspecificgravity60/60°F,isrecommended.Onesuggestedprocedureisthefollowing:Ifaconstant-temperaturewaterbathisnotavailable,deter-minethemassoftheclean,drypycnometerwiththermometerTABLE2TestMethodBSpecificGravityTestedinLiquidsOtherThanWaterMaterialMeanSrASRBrCRDPolypropylene0.90230.001390.002390.003930.00669LDPE0.92150.001090.001950.003080.00546HDPE0.96780.001260.001890.003560.00529Thermoset1.31300.001600.002170.004530.00608ASr=withinlaboratorystandarddeviationfortheindividualmaterial.Itisobtainedbypoolingthewithin-laboratorystandarddeviationsofthetestresultsfromalloftheparticipatinglaboratories:Sr=[[(s1)2+(s2)2...+(sn)2]/n]1/2BSR=between-laboratoriesreproducibility,expressedasstandarddeviation:SR=[Sr2+SL2]1/2whereSListhestandarddeviationoflaboratorymeans.Cr=within-laboratorycriticalintervalbetweentwotestresults=2.8×Sr.DR=between-laboratoriescriticalintervalbetweentwotestresults=2.8×SR.TABLE3StandardDensityofWaterA°Cρ=/kgm–30.00.10.20.30.40.50.60.70.80.921997.994897319513929490738852863084068182795722997.773075037275704568156584635161185883564823997.541251744936469744564215397337303485324024997.299427472499225020001749149712440990073525997.048002239965B9707B9447B9186B8925B8663B8399B8135BAObtainedfromCRCHandbookofChemistryandPhysics,78thedition,1997-1998.BTheleadingfiguredecreasesby1.D792−134CopyrightASTMInternational--``,`````,``,``,`,,`,,```````,,-`-`,,`,,`,`,,`---tothenearest0.1mgonananalyticalbalance.Fillthepycnometerwithwater(10.1)coolerthan23°C.Insertthethermometer-stopper,causingexcesswatertobeexpelledthroughthesidearm.Permitthefilledbottletowarminairuntilthethermometerreads23.0°C.Removethedropofwateratthetipofthesidearmwithabitoffilterpaper,takingcarenottodrawanyliquidfromwithinthecapillary,placethecapoverthesidearm,wipetheoutsidecarefully,anddeterminethemassofthefilledbottleagaintothenearest0.2mg.Emptythepycnometer,dry,andfillwithimmersionliquid.Determinethemasswiththeliquidinthesamemanneraswasdonewiththewater.Calculatethespecificgravity23/23°Coftheliquid,d,asfollows:d5~b2e!/~w2e!where:e=apparentmassofemptypycnometer,w=apparentmassofpycnometerfilledwithwaterat23.0°C,andb=apparentmassofpycnometerfilledwithliquidat23.0°C.Ifaconstant-temperaturewaterbathisavailable,apycnom-eterwithoutathermometermaybeused(compare30.2).NOTE16—OnestandardobjectwhichhasbeenfoundsatisfactoryforthispurposeistheReimannThermometerPlummet.Thesearenormallysuppliedcalibratedformeasurementsattemperaturesotherthan23/23°C,sothatrecalibrationisnotnecessaryforthepurposesofthesemethods.19.TestSpecimen19.1SeeSection11.20.Procedure20.1TheprocedureshallbesimilartoSection12,exceptforthechoiceofimmersionliquid,andthetemperatureduringtheimmersedweighing(12.3)shallbe2360.5°C.21.Calculation21.1ThecalculationsshallbesimilartoSection13,exceptthatd,thespecificgravity23/23°Coftheliquid,shallbeplacedinthenumerator:(see13.1)Spgr23/23°C5~a3d!/~a1w2b!22.Report22.1SeeSection14.23.PrecisionandBias23.1Tables1and2arebasedonaninterlaboratorystudy4conductedin1985inaccordancewithPracticeE691,involving5materialstestedwithTestMethodAbysixlaboratoriesorfourmaterialstestedwithTestMethodBbysixlaboratories.Eachtestresultwasbasedontwoindividualdeterminationsandeachlaboratoryobtainedfourtestresultsforeachmaterial.(Warning—TheexplanationsofrandRareonlyintendedtopresentameaningfulwayofconsideringtheapproximateprecisionofthesetestmethods.ThedataofTables1and2shouldnotbeappliedtoacceptanceorrejectionofmaterials,asthesedataapplyonlytothematerialstestedintheroundrobinandareunlikelytoberigorouslyrepresentativeofotherlots,formulations,conditions,materials,orlaboratories.UsersofthistestmethodshouldapplytheprinciplesoutlinedinPracticeE691togeneratedataspecifictothematerialsandlaboratory(orbetweenspecificlaboratories).Theprinciplesof23.2–23.2.3wouldthenbevalidforsuchdata.)23.2ConceptofrandRinTables1and2—IfSrandSRhavebeencalculatedfromalargeenoughbodyofdata,andfortestresultsthatwereaveragesfrom4testresultsforeachmaterial,then:23.2.1Repeatability—Twotestresul