Designation:D991-89 (Reapproved2014) INTERNATIONAL Standard Test Method for Rubber PropertyVolume Resistivity Of Electrically Conductive andAntistaticProducts This standard is issued under the fixed designation D991; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) 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. Scope 3.1.1.1 Discussion-Generally, antistatic rubber products are considered to have a resistance of 10 to 10° 2. 1.1 This test method covers the determination of volume 3.1.2 rubber product, conductive—a rubber product having resistivity of rubbers used in electrically conductive and antistatic products. an electrical conductivity of sufficient magnitude that might be considered an electrical or thermal hazard. 1.2 This test method assumes that the surface conductivity 3.1.2.1 Discussion—Generally, conductive rubber products is negligible compared with the conductivity through the are considered to have a resistance of less than 10* at 120 V. specimen. 3.1.3 volume resistivity—the ratio of the electric potential 1.3 The values stated in SI units are to be regarded as the gradient to the current density when the gradient is parallel to standard. The values given in parentheses are for information the current in the material. only. 1.4 This standard does not purport to address all of the 4. Significance and Use safety concerns, if any, associated with its use. It is the 4.1 The electrical behavior of rubber products used in responsibilityoftheuserofthisstandardtoestablishappro particular applications is important for a variety of reasons priate safety and health practices and determine the applica- such as safety,static changes,current transmission,etc.This bility of regulatory limitations prior to use. test method is useful in predicting the behavior of such rubber products. 2.Referenced Documents 2.1 ASTM Standards:2 5.Apparatus D3182 Practice for Rubber-—Materials, Equipment, and Pro- 5.1Electrode Assembly-The electrode assembly (Fig.1) cedures for Mixing Standard Compounds and Preparing shall consist of a rigid base made from an electrically insulat- Standard Vulcanized Sheets ing material having a resistivity greater than 10 TQ-m (for D4483 Practice for Evaluating Precision for Test Method example, hard rubber, polyethylene, polystyrene, etc.) to which Standards in the Rubber and Carbon Black Manufacturing a pair of current electrodes and a pair of potential electrodes are Industries fastened in such a manner that the four electrodes are parallel and their top surfaces are in the same horizontal plane. Another 3.Terminology pair of current electrodes identical with the first pair shall be 3.1 Definitions of Terms Specific to This Standard: fastenedto a secondpiece of insulatingmaterial so that they 3.1.1rubber product, antistatic-a rubber product suffi- canbe superimposedonthe specimendirectly abovethefirst ciently conductive to prevent a build-up of an electrical charge pair. The current electrodes shall have a length at least 10 mm on the surface and sufficiently insulating to prevent an electri- (0.4 in.) greater than the specimen width, a width between 5 cal hazard. and 8 mm (0.2 and 0.3 in.), and a height uniform within 0.05 mm (0.002 in.) between 10 and 15 mm (0.4 and 0.6 in.). The potential electrodes shall have a length and height equal to the I This test method is under the jurisdiction of ASTM Committee DI1 on Rubber current electrodes and shall be tapered to an edge having a and is the direct responsibility of Subcommittee D11.10 on Physical Testing radius of 0.5 mm (0.02 in.)maximum at the top surface. The Current edition approved Nov. 1, 2014. Published December 2014. Originally approved in 1948. Last previous