塑料测试方法.docx

塑料测试方法.docx

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塑料测试方法

TensileProperties-ASTMD638

Tensiletestingisperformedbyelongatingaspecimenandmeasuringtheloadcarriedbythespecimen.Fromaknowledgeofthespecimendimensions,theloadanddeflectiondatacanbetranslatedintoastress-straincurve.Avarietyoftensilepropertiescanbeextractedfromthestress-straincurve.

TensileTest

Property

Definition

TensileElongationatBreak

Tensileelongationcorrespondingtothepointofrupture.

TensileElongationatYield

Tensileelongationcorrespondingtotheyield（anincreaseinstraindoesnotresultinanincreaseinstress）.

TensileStrengthatBreak

Tensilestresscorrespondingtothepointofrupture.

TensileStrengthatYield

Tensilestresscorrespondingtotheyieldpoint（anincreaseinstraindoesnotresultinanincreaseinstress）.

TensileStrength

Tensilestressataspecifiedelongation.

TensileStrength,Ultimate

Thehighesttensilestressamaterialcansupportbeforefailing.

TensileModulus

Theratiooftensilestresstotensilestrainofamaterialintheelasticregionofastress-straincurve.A"Tangent"tensilemodulusvalueistheslopeoftheelasticregionofthestress-straincurveandisalsoknownasYoung'sModulus,ortheModulusofElasticity.A"Secant"tensilemodulusvalueistheslopeofalineconnectingthepointofzerostraintoapointonthestress-straincurveataspecifiedstrain.Thisisusedformaterialsthatexhibitlittleornolinearbehavior.

IllustrationofTangentandSecantTensileModuli

TestSpecimenSummary

Specimen

RigidityCase

Note

Thickness

TypeI

Rigid

Preferredspecimen.

<7mm（0.28in）

TypeII

Rigid

UsewhenTypeIspecimendoesnotbreakinthenarrowsection.

<7mm（0.28in）

TypeIII

Rigid/Nonrigid

>7mm（0.28in）

<14mm（0.55in）

TypeIV

Rigid/Nonrigid

Shouldbeusedforcomparisonbetweenmaterialsindifferentrigiditycases.EssentiallythesameasDieCspecimenfromASTMD412.

<4mm（0.16in）

TypeV

Rigid

Usedwhenlimitedmaterialisavailableorlaboratoryspaceisaconcern（forenvironmentaltesting）

<4mm（0.16in）

TypeI,II,III,andVSpecimen

TypeIVSpecimen

FlexuralProperties-ASTMD790

Atestspecimenisheldasasimplysupportedbeamandissubjectedtothree-pointbending.Thespecimenisdeflecteduntiliteitherbreaksortheouterfiberstrainreaches5%.

Twoproceduresareusedforflexuraltesting.

Procedure

Description

StrainRate

A

Formaterialsthatbreakatrelativelysmalldeflections.

0.01mm/mm/min

B

Formaterialsthatundergolargedeflectionsduringtesting.

0.10mm/mm/min

FlexuralTestConfiguration

LocationofMaximumFiberStress/Strain

Term

Definition

FlexuralModulus

Theratioofouterfiberstresstoouterfiberstrain.

FlexuralStressatYield

Theouterfiberstresscorrespondingtotestspecimenyield.

FlexuralStressatBreak

Theouterfiberstresscorrespondingtotestspecimenfailure.

FlexuralStrength

Themaximumouterfiberstresssustainedbyaspecimenduringtesting.

IzodImpactStrength-ASTMD256

Energyperunitthicknessrequiredtobreakatestspecimenunderflexuralimpact.Testspecimenisheldasaverticalcantileveredbeamandisimpactedbyaswingingpendulum.Theenergylostbythependulumisequatedwiththeenergyabsorbedbythetestspecimen.

Notes:

∙CharpyImpactStrengthisnolongercoveredunderthistestmethod,butisincludedbecauseCharpyvaluesarestillreportedunderthismethod.

∙UnnotchedIzodImpactStrength,coveredbyASTMD4812,isincludedherebecauseitisoftencitedasbeingtestedbyASTMD256.

∙Optionalunitsofenergyperunitareaaresupportedbythestandard.ThesearetheISOstyleunits.

NotchedIzodSpecimen

Method

Name

TestDescription

Diagram

A

NotchedIzodImpactStrength

Specimenisheldasaverticalcantileveredbeamandisbrokenbyapendulum.Impactoccursonthenotchedsideofthespecimen.

B

CharpyImpactStrength

Specimenisheldasasimplysupportedbeamandisimpactedonthesideoppositethenotch.ThismethodisnolongercoveredunderASTMD256butisstillreportedassuch.

C

EstimatedNetIzodImpactStrength

ThismethodisthesameasMethodAexceptthattheenergyrequiredtotossthebrokenportionofthespecimenisincludedintheenergycalculation.PreferredoverMethodAformaterialswithimpactstrengthbelow27J/m（0.5ft-lb/in）

D

NotchRadiusSensitivityTest

Providesanindicationofnotchsensitivity.Notchsensitivityiscalculatedusing:

b=（E2-E1）/（R2-R1）

wherebisthenotchsensitivity,E1andE2aretheenergyrequiredtobreakasmallandlargeradiusnotchedspecimen,andR1andR2aretheradiiofthesmallandlargeradiusnotches.UnitsareJ/m/mmofnotchradius.

E

ReversedNotchedIzodImpactStrength

SametestasMethodAexceptthespecimenisimpactedonthesideoppositethenotch.

UnnotchedIzodImpactStrength

Unnotchedspecimenisheldasaverticalcantileveredbeamandisbrokenbyapendulum.ThismethodiscoveredunderASTMD4812butiscommonlyreportedunderASTMD256.

InstrumentedDartImpact-ASTMD3763

Theenergyrequiredtopunctureamaterialbyimpactwithafallingdartunderspecifiedtestconditions.Thistestmeasuresthemultiaxialimpactbehaviorofamaterialandcanbeusedasameasureoftheratesensitivityofamaterial.

ImpactorHead

A12.7mm（0.5in）diameterhemisphericalheaddartisdroppedfromaheightsufficienttoproduceaspecifiedimpactvelocity.Thedartisequippedwithloadanddisplacementtransducerssothataload/displacementplotofthetestcanbeproduced.Energyistheareabeneaththeload/displacementplot.Energyreportediseitherenergytopeakloadortotalenergy.

EnergyTypes

VicatSofteningTemperature-ASTMD1525

Thetemperatureatwhicha1mm2flat-endedneedlewillpenetrate1mmintoamaterialunderaspecifiedloadandheatingrate.Thevicatsofteningtemperaturecanbeusedtocomparetheheat-softeningcharacteristicsofdifferentmaterials.

Twodifferentheatingratesandtwodifferentloadsmaybeusedfortesting.

HeatingRateA:

50°C/hr

HeatingRateB:

120°C/hr

Loading1:

10N（1kg）

Loading2:

50N（5kg）

DeflectionTemperatureUnderLoad（DTUL）-ASTMD648

Thetemperatureatwhichatestspecimendeflects0.25mmwhenloadedin3-pointbendingataspecifiedmaximumouterfiberstress.Deflectiontemperatureisusedtodetermineshort-termheatresistance.

Atestspecimenisloadedin3-pointbendingintheedgewisedirection.Outerfiberstressesusedfortestingare0.455MPa（66psi）and1.82MPa（264psi）.Thetemperatureisincreasedat2°C/minuntilthespecimendeflects0.25mm（0.010in）.

CoefficientofLinearThermalExpansion（CLTE）-ASTME831

Thechangeinlengthperunitlengthofamaterialperdegreeoftemperaturechange.

CLTEismeasuredusingathermomechanicalanalyzer.Thespecimenisheldinanenclosureandiscontactedbyaprobeleadingtoadisplacementsensor.Asmallforceof1to100mNisappliedtothespecimentokeeptheprobeincontactwiththespecimen.

ThermomechanicalAnalyzerSetup

Theenclosureisbroughttoastartingtemperature.Thetemperaturewithintheenclosureisincreasedatarateof5°C/min.Theexpansionofthespecimenismeasuredbythedisplacementsensoroverthetemperaturerangeofinterest.ASTME831coverstemperaturesbetween-120and600°C.

CLTE（α）iscalculatedusingtheformula:

α=ΔL/（Lo*ΔT）

whereΔListhechangeinlengthofthespecimen,

Loistheoriginallengthofthespecimen,

andΔTisthetemperaturechangeduringthetest.

WaterAbsorption-ASTMD570

Thepercentincreaseinweightofamaterialafterexposuretowaterunderspecifiedconditions.Waterabsorptioncaninfluencemechanicalandelectricalproperties.Factorssuchasthetypeofmaterial,additives,temperature,andlengthofexposurecanaffecttheamountofwaterabsorbed.

Fortesting,thespecimensaredriedandcooled.Threetestingproceduresarecommonlyemployed.Onlydatafromthesametestingproceduresarereadilycomparable.

Procedure

TestDescription

WaterAbsorption@24hrs

Testspecimensareimmersedindistilledwaterataspecifiedtemperaturefor24hours.Testingismostcommonlydoneat23°C（73.4°F）

WaterAbsorption@Saturation

Testspecimensareimmersedindistilledwaterataspecifiedtemperatureuntilthewaterabsorptionessentiallyceases.

WaterAbsorption@Equilibrium.

Testspecimensareexposedtoahumidenvironmentataspecifiedtemperaturefor24hours.Testingismostcommonlyperformedat50%relativehumidity（RH）and23°C（73.4°F）.

MeltMass-FlowandMeltVolume-FlowRate-ASTMD1238

Extrusionrateofaresinthroughanorificeofdefineddimensionsataspecifiedtemperatureandload.Flowratescanbeusedtodifferentiategradesorprovideameasureofdegradationofamaterialasaresultofmolding.

MeltFlowRateProcedures

Procedure

Description

A

ManualOperation

B

AutomaticallyTimedFlowRateMeasurement

C

AutomaticallyTimedFlowRateMeasurementforHighFlowRatePolyolefinsUsingHalf-Height,HalfDiameterDie

Thetestingconditionsaremostcommonlyreportedastemperature/load（i.e.190°C/2.16kg）.Inthepastseveraltestconditionsweregivenalphabeticaldesignations,thesedesignationsaredescribedbelow.

HistoricalMeltFlowRateConditions

Condition

Temperature（°C）

Load（kg）

A

125

0.325

B

125

2.16

C

150

2.16

D

190

0.325

E

190

2.16

F

190

21.6

G

200

5

H

230

1.2

I

230

3.8

J

265

12.5

K

275

0.325

L

230

2.16

M

190

1.05

N

190

10

O

300

1.2

P

190

5

Q

235

1

R

235

2.16

S

235

5

T

250

2.16

U

310

12.5

V

310

2.16

W

285

2.16

X

315

5