ASTM_D_991_-_89_2014.pdf

Designation:D99189(Reapproved 2014)Standard Test Method forRubber PropertyVolume Resistivity Of ElectricallyConductive and Antistatic Products1This standard is issued under the fixed designation D991;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 U.S.Department of Defense.1.Scope1.1 This test method covers the determination of volumeresistivity of rubbers used in electrically conductive andantistatic products.1.2 This test method assumes that the surface conductivityis negligible compared with the conductivity through thespecimen.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.4 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:2D3182 Practice for RubberMaterials,Equipment,and Pro-cedures for Mixing Standard Compounds and PreparingStandard Vulcanized SheetsD4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustries3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 rubber product,antistatica rubber product suffi-ciently conductive to prevent a build-up of an electrical chargeon the surface and sufficiently insulating to prevent an electri-cal hazard.3.1.1.1 DiscussionGenerally,antistatic rubber productsare considered to have a resistance of 104to 108.3.1.2 rubber product,conductivea rubber product havingan electrical conductivity of sufficient magnitude that might beconsidered an electrical or thermal hazard.3.1.2.1 DiscussionGenerally,conductive rubber productsare considered to have a resistance of less than 104 at 120 V.3.1.3 volume resistivitythe ratio of the electric potentialgradient to the current density when the gradient is parallel tothe current in the material.4.Significance and Use4.1 The electrical behavior of rubber products used inparticular applications is important for a variety of reasonssuch as safety,static changes,current transmission,etc.Thistest method is useful in predicting the behavior of such rubberproducts.5.Apparatus5.1 Electrode AssemblyThe electrode assembly(Fig.1)shall consist of a rigid base made from an electrically insulat-ing material having a resistivity greater than 10 Tm(forexample,hard rubber,polyethylene,polystyrene,etc.)to whicha pair of current electrodes and a pair of potential electrodes arefastened in such a manner that the four electrodes are paralleland their top surfaces are in the same horizontal plane.Anotherpair of current electrodes identical with the first pair shall befastened to a second piece of insulating material so that theycan be superimposed on the specimen directly above the firstpair.The current electrodes shall have a length at least 10 mm(0.4 in.)greater than the specimen width,a width between 5and 8 mm(0.2 and 0.3 in.),and a height uniform within 0.05mm(0.002 in.)between 10 and 15 mm(0.4 and 0.6 in.).Thepotential electrodes shall have a length and height equal to thecurrent electrodes and shall be tapered to an edge having aradius of 0.5 mm(0.02 in.)maximum at the top surface.Thedistance between the potential electrodes shall not be less than10 mm(0.4 in.)nor more than 66 mm(2.6 in.)and shall beknown within 62%.The current electrodes shall be equidis-tant outside the potential electrodes and separated from themby at least 20 mm(0.8 in.).The electrodes shall be made from1This 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 Nov.1,2014.Published December 2014.Originallyapproved in 1948.Last previous edition approved in 2010 as D991 89(2010).DOI:10.1520/D0991-89R14.2For 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 a corrosion-resistant metal such as brass,nickel,stainless steel,etc.Insulation resistance between electrodes shall be greaterthan 1 T.5.2 Resistance-Measuring DeviceResistance may be mea-sured by any electrical circuit that enables the current throughthe current electrodes and the potential across the potentialelectrodes to be measured within 2%.Suitable devices formeasuring current are:(1)a precision milliammet