Designation:D7050−04(Reapproved2014)StandardPracticeforRubberfromNaturalSources—SamplingandSortingBalesBasedonPredictedProcessingProperties1ThisstandardisissuedunderthefixeddesignationD7050;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1ThispracticecoversthesortingofnaturalrubberbalesofTSR10orTSR20inthefactoryaccordingtotheirpredictedprocessingperformancebasedondifferencesinviscoelasticproperties.1.2Thispracticedetermineswhichbalesshouldbeusedinfactorycompoundswhichbenefitfromusing“soft”naturalrubberversuswhichworkbetterwith“hard”naturalrubber.2.ReferencedDocuments2.1ASTMStandards:2D1485PracticeforRubberfromNaturalSources—SamplingandSamplePreparationD2227SpecificationforNaturalRubber(NR)TechnicalGradesD3194TestMethodforRubberFromNaturalSources—PlasticityRetentionIndex(PRI)D6204TestMethodforRubber—MeasurementofUnvulca-nizedRheologicalPropertiesUsingRotorlessShearRhe-ometers3.SignificanceandUse3.1InaccordancewithSpecificationD2227,shipmentsofTSR10andTSR20mustmeetaminimuminitialWallaceplasticity(Po)of30tobeaccepted.However,evenwiththisminimumrestriction,theuncuredviscoelasticor“processabil-ity”propertiesareallowedtovarygreatly.Thisvariationinpropertiescansignificantlyaffectthequalityandefficiencyofafactoryoperation.3.2BalesofTSR10orTSR20whicharelowerintheiruncuredelasticquality(“soft”rubber)insomecasesmayimpartbetterprocessingpropertiestotireinnerliners,cushiongums,andsidewalls.“Soft”balessometimesimpartbetterbuildingtack,bettermoldflow,andlowerextrusiondieswellwithbetterdimensionalstability.Also,these“soft”rubberbalesmaydissolvefasterinsolventsforadhesiondipping.3.3BalesofTSR10orTSR20thatarehigherintheiruncuredelasticquality(“hard”rubber)insomecasesgenerategreatershearingduringtheinitialstagesofafactorymix,whichresultinafasterbrea...
