ASTM_D_7121_-_05_2012.pdf

Designation:D712105(Reapproved 2012)Standard Test Method forRubber PropertyResilience Using Schob Type ReboundPendulum1This standard is issued under the fixed designation D7121;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.1.Scope1.1 This test method covers a means of determining theresilience of rubber,within a range of impact strain and strainrate,by means of the impacting and measuring apparatusconforming to the requirements described in this test method.1.2 This test method is applicable to thermoset rubbers andthermoplastic elastomers,the hardness of which,at the speci-fied test temperatures,lies between 30 and 85 IRHD(see TestMethod D1415)or A/30 and A/85(see Test Method D2240).Itmay also be applicable to some polyester,polyether foam,andplastic foam materials.1.3 All materials,instruments,or equipment used for thedetermination of mass,force,or dimension shall have trace-ability to the National Institute for Standards and Technology,or other internationally recognized organization parallel innature.1.4 The values stated in SI units are to be regarded asstandard.The values given in parentheses are for informationonly.1.5 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:2D832 Practice for Rubber Conditioning For Low Tempera-ture TestingD1349 Practice for RubberStandard Conditions for Test-ingD1415 Test Method for Rubber PropertyInternationalHardnessD2240 Test Method for Rubber PropertyDurometer Hard-nessD3182 Practice for RubberMaterials,Equipment,and Pro-cedures for Mixing Standard Compounds and PreparingStandard Vulcanized SheetsD3183 Practice for RubberPreparation of Pieces for TestPurposes from ProductsD4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustries3.Summary of Test Method3.1 This test method describes the determination ofresilience,expressed as percentage resilience or reboundresilience,by a Schob Type pendulum rebound device as a ratiobetween the returned and applied energy when a sphericallyterminated mass impacts a test specimen under the conditionsspecified in this test method.3.2 Resilience of the materials described is infinitely vari-able.It varies with temperature,strain rate(specifically relatedto the velocity of the indentor),and strain energy(specificallyrelated to the mass of the indentor,coupled with velocity).3.3 The variable factors,described and defined in this testmethod,will have effects on the outcomes of test results.Repetitive tests,under the defined conditions,on comparablematerials,will provide meaningful,repeatable,and reproduc-ible data.4.Significance and Use4.1 The Schob Type rebound pendulum is designed tomeasure the percentage resilience of a rubber compound as anindication of hysteretic energy loss that can also be defined bythe relationship between storage modulus and loss modulus.The percent rebound measured is inversely proportional to thehysteretic loss.4.1.1 Percentage resilience or rebound resilience are com-monly used in quality control testing of polymers and com-pounding chemicals.4.1.2 Rebound resilience is determined by a freely fallingpendulum hammer that is dropped from a given height thatimpacts a test specimen and imparts to it a certain amount ofenergy.A portion of that energy is returned by the specimen to1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.10 on Physical Testing.Current edition approved May 1,2012.Published July 2012.Originally approvedin 2005.Last previous edition approved in 2005 as D7121 05.DOI:10.1520/D7121-05R12.2For 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 the pendulum and may be measured by the extent to which thependulum rebounds,whereby the restoring force is determinedby gravity.4.1.2.1 Since the energy of the pendulum is proportional tothe vertical component of the displacement of the pendulum,itmay be expressed as 1 cos(of the angle of displacement)andpercentage rebound resilience.RB,commonly called percent-age rebound,is determined from the equation:RB51 2 cosangle of rebound!1 2 cosoriginal angle!3100(1)4.1.2.2 The rebound resilience may be calculated as:R 5hH(2)where:h=apex hei