ASTM D7474-2008 通过浸入各种化学试剂中测定挤压或模铸砜塑料件中残余应力的标准实施规程

作者:标准资料网 时间:2024-05-21 08:48:29  浏览:8360   来源:标准资料网

【英文标准名称】:StandardPracticeforDeterminingResidualStressesinExtrudedorMoldedSulfonePlastic(SP)PartsbyImmersioninVariousChemicalReagents
【原文标准名称】:通过浸入各种化学试剂中测定挤压或模铸砜塑料件中残余应力的标准实施规程
【标准号】:ASTMD7474-2008
【标准状态】:现行
【国别】:美国
【发布日期】:2008
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:D20.15
【标准类型】:(Practice)
【标准水平】:()
【中文主题词】:
【英文主题词】:liquidreagent;PESU;PPSU;PSU;residualstress;SP;stresscracking
【摘要】:Thermoplasticmoldingscontainresidualstressesduetodifferentialcoolingratesthroughthethicknessofthemolding.Changesinresidualstresshavebeenfoundtooccurwithtimeaftermoldingduetostressrelaxation.Manypartperformanceparametersaswellaspartfailuresareaffectedbythelevelofresidualstresspresentinapart.Residualstressescauseshrinkage,warpage,andadecreaseinenvironmentalstresscrackresistance.Thispracticeestimatestherelativemagnitudeofresidualstressesinpartsproducedfromtheseriesofsulfoneplastics(SP),namelypolysulfone(PSU),polyethersulfone(PESU),andpolyphenylsulfone(PPSU)materials.Nodirectcorrelationhasbeenestablishedbetweentheresultsofthedeterminationofresidualstressesbythispracticeandpartperformanceproperties.Forthisreason,thispracticeisnotrecommendedasasubstituteforothertests,norisitintendedforuseinpurchasingspecificationsforparts.Despitethislimitation,thispracticedoesyieldinformationofvalueinindicatingthepresenceofresidualstressesandtherelativequalityofplasticparts.Residualstressescannotbeeasilycalculated,henceitisimportanttohaveanexperimentalmethod,suchasthispractice,toestimateresidualstresses.ThispracticeisusefulforextrudersandmolderswhowishtoevaluateresidualstressesinSPparts.Thiscanbeaccomplishedbyvisualexaminationafterimmersioninoneormorechemicalreagentstoevaluatewhetherornotcrackingoccurs.Stresseswillrelaxaftermoldingorextrusion.Accordingly,bothimmersioninthetestmediumandvisualexaminationmustbemadeatidenticaltimesandconditionsafterprocessing,ifcomparingparts.Itisimportanttonotethedifferencesinparthistory.Thus,thistechniquemaybeusedasanindicationforqualityofplasticprocessing.Thepracticeisusefulprimarilyforindicatingresidualstressesnearthesurface.1.1ThispracticecoverstheevaluationofresidualstressesinextrudedprofileormoldedSPparts.Thepresenceandrelativemagnitudeofresidualstressesareindicatedbythecrazingofthespecimenpartuponimmersioninoneormoreofaseriesofchemicalreagents.ThespecifiedchemicalreagentswerepreviouslycalibratedbyuseofEnvironmentalStressCracking(ESC)techniquestocausecrazinginsulfoneplastics(SP)atspecifiedstresslevels.1.2Thispracticeappliesonlytounfilledinjectionmoldingandextrusiongradematerialsofhighmolecularweightasindicatedbythefollowingmeltflowrates:PSU9g/10min,max.,PESU30g/10m,max,andPPSU25g/10min,max.Lowermolecularweight(highermeltflow)materialswillcrazeatlowerstresslevelsthanindicatedinTables1-3.(SeeSpecificationD6394formeltflowrateconditions.)1.3ThevaluesstatedinSIunitsaretoberegardedasthestandard.Thevaluesgiveninparenthesesareforinformationonly.Note18212;ThereisnoequivalentISOstandard.1.4Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimitationspriortouse.
【中国标准分类号】:G31
【国际标准分类号】:83_080_01
【页数】:4P.;A4
【正文语种】:英语