ASTM_D_832_-_07_2012.pdf

Designation:D83207(Reapproved 2012)Standard Practice forRubber Conditioning For Low Temperature Testing1This standard is issued under the fixed designation D832;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1.Scope1.1 This practice covers the characteristic mechanical be-havior of rubbers at low temperatures,and outlines the condi-tioning procedure necessary for testing at these temperatures.1.2 One of the first stages in establishing a satisfactorytechnique for low temperature testing is the specification of thetime and temperature of exposure of the test specimen.It hasbeen demonstrated that any one or more of the followingdistinct changes,which are detailed in Table 1,may take placeon lowering the test temperature:1.2.1 Simple temperature effects,1.2.2 Glass transitions,and1.2.3 First order transitions(crystallization),and solubilityand other effects associated with plasticizers.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D471 Test Method for Rubber PropertyEffect of LiquidsD1053 Test Methods for Rubber PropertyStiffening atLow Temperatures:Flexible Polymers and Coated FabricsD1329 Test Method for Evaluating Rubber PropertyRetraction at Lower Temperatures(TR Test)D1566 Terminology Relating to RubberD2136 Test Method for Coated FabricsLow-TemperatureBend TestD5964 Practice for Rubber IRM 901,IRM 902,and IRM903 Replacement Oils forASTM No.1,ASTM No.2,andASTM No.3 Oils3.Significance and Use3.1 Low temperature testing of rubber can yield repeatableresults only if the preconditioning of the samples is consistent.Properties such as brittleness and modulus are greatly affectedby variations in time/temperature exposures.This practice isintended to provide uniform conditioning for the various lowtemperature tests conducted on rubbers.4.General Conditioning4.1 At least 16 h should elapse between vulcanization andtesting of a sample.4.1.1 If the time between vulcanization and testing is lessthan 16 h,it shall be agreed upon between customer andsupplier and noted in the report section of the test methodemployed.5.Simple Temperature Effects(Viscoelasticity)5.1 Most elastic properties of rubber change as the tempera-ture is changed.As the temperature is reduced toward the glasstransition temperature,Tg,the specimen becomes increasinglystiff,loses resilience,and increases in modulus and hardness.At some point,still above Tg,the resilience reaches a mini-mum.As the temperature is lowered beyond this point,theresilience then increases until a temperature just above Tgisreached.5.2 Viscoelastic changes are usually complete as soon as thespecimen has reached thermal equilibrium.Longer exposuretime should be avoided to minimize crystallization orplasticizer-time effects that might influence the test results.Themagnitude of these changes depends on the composition of thematerial and the test temperature.6.Glass Transition6.1 Glass transition is a reversible physical change in amaterial from a viscous or rubbery state to a brittle glassy state(refer to Terminology D1566:transition,glass;transitionsecond order).It does not involve a change in phase and is nota thermodynamic change.It generally occurs over a smalltemperature range.It is designated as Tg.The Tgof polymers,obtained from measurements of change of modulus withchange in temperature,depend upon both the rate of specimendeformation and the rate of temperature change.Primary1This practice is under the jurisdiction ofASTM Committee D11 on Rubber andis the direct responsibility of Subcommittee D11.10 on Physical Testing.Current edition approved Dec.1,2012.Published February 2013.Originallyapproved in 1945.Last previous edition approved in 2007 as D832 07.DOI:10.1520/D0832-07R12.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 properties,such as hardness and ultimate elongation,andtemperature coefficients of properties such as volume andenthalpy,change rapidly near Tg.Thus,thermal expansivityand specific heat appear discontinuous at Tg.6.2 Some rubbers such as copolymers or polymer blendsmay show more than a single Tgbecause of separate contri-butions by their polymeric components.There