ASTM_D_4620_-_02_2012.pdf

Designation:D462002(Reapproved 2012)Standard Test Method forEvaluating the Effective Surface Area of Zinc Oxide inRubber1This standard is issued under the fixed designation D4620;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 specifies the standard materials,mix-ing procedure,and test method for ranking zinc-oxide samplesaccording to their specific surface area in a standard testformula based on chloroprene rubber(CR).1.2 The ranking is based on the cure time of the standard CRformulation.1.3 The accurate surface area cannot be determined by thistest method,since factors other than surface area may influencethe cure times to some extent(for example acidity,heavy metaltraces,etc.).1.4 The values stated in SI units are to be regarded as thestandard.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:2D1646 TestMethodsforRubberViscosity,StressRelaxation,andPre-VulcanizationCharacteristics(Mooney Viscometer)D2084 Test Method for Rubber PropertyVulcanizationUsing Oscillating Disk Cure MeterD3190 Test Method for RubberEvaluation of ChloropreneRubber(CR)D5289 Test Method for Rubber PropertyVulcanizationUsing Rotorless Cure Meters3.Summary of Test Method3.1 Separate formulations of a chloroprene-rubber com-pound are prepared containing 3-methyl-thiazolidine-thione-2and other compounding materials.One or more formulation(s)contain the experimental or candidate zinc-oxide grade(s)to beevaluated and the other standard formulation(s)one or morezinc-oxide grade(s)of known surface area.3.2 The cure times(t890)of the formulations are measuredas specified in Test Method D2084 or D5289 and used to rankthe unknown zinc-oxide with respect to the standard containingzinc oxide of known surface area.3.3 Longer cure times indicate lower surface areas,andshorter cure times indicate higher surface areas.4.Significance and Use4.1 The surface area of zinc-oxide in rubber can signifi-cantly affect cure activation and vulcanizate properties.4.2 The specific surface area of zinc-oxide is usually mea-sured by nitrogen absorption which requires the use of equip-ment not normally found in rubber laboratories.This testmethod allows a ranking of zinc-oxide samples according totheir surface areas with respect to a known standard using asimplified procedure involving mixing of rubber compoundsand measuring cure times with oscillating disk or rotorless curemeters.4.3 This test method may be used for quality control,research and development work,and comparison of differentzinc-oxide samples.5.Standard Test Formula5.1 The standard test formula is similar to Formula B in TestMethod D3190,except for the curative(see Table 1).5.2 For meaningful results,it is necessary to use the samelot of raw materials within each test series.6.Mixing Procedures6.1 The mill mixing procedure outlined in Test MethodD3190(6.1.2.,Method B and 6.4)is employed.1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.20 on Compounding Materialsand Procedures.Current edition approved May 1,2012.Published June 2012.Originallyapproved in 1986.Last previous edition approved in 2007 as D4620 02(2007).DOI:10.1520/D4620-02R12.2For 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 6.2 Mill-roll temperatures are adjusted to 50 6 5C(122 69F)and stock temperatures should reach 75 6 5C(167 69F)to assure melting and satisfactory dispersion of thecurative.6.3 It is recommended that the 3-methyl-thiazolidine-thione-2 be pulverized in order to prevent any loss by granulespopping off the mill during the mixing cycle.7.Testing7.1 Individual formulations containing one or more zinc-oxide samples of unknown and known surface areas are mixedand t890 times are measured in accordance with Test MethodD2084 or Test Method D5289,using a temperature of 160C(320F).7.2 The t890 times of the formulation(s)containing zinc-oxide of unknown surface area are ranked with respect to theknown standard(s)and each other.7.3 As zinc-oxide standard IRM 913or any other grade ofknown surface area,or both can be employed.7.4 Similar t890 times indicate similar surface area