ASTM_D_4949_-_94_2002.pdf

Designation:D 4949 94(Reapproved 2002)An American National StandardStandard Test Method forDetermination of D-C Resistivity of Writing Paper(KeithleyMethod)1This standard is issued under the fixed designation D 4949;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method describes the procedure for determina-tion of both surface and volume(bulk)d-c resistivity of writingpaper.This test method is specific for the Keithley 6105resistivity adapter.1.2 This test method has been developed as a special casefor use on writing papers processed in high-speed nonimpactprinters where resistivity control is critical.It is not in conflictwith Test Methods D 257.1.3 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:D 257 Test Methods for D-C Resistance or Conductance ofInsulating Materials2D 585 Practice for Sampling and Accepting a Single Lot ofPaper,Paperboard,Fiberboard,and Related Products3D 644 Test Method for Moisture Content of Paper andPaperboard by Oven Drying3D 645 Test Method for Thickness of Paper and Paperboard3D 685 Practice for Conditioning Paper and Paper Productsfor Testing3D 1749 Practice for Interlaboratory Evaluation of TestMethods Used with Paper and Paper Products3E 122 Practice for Calculating Sample Size to Estimate,with a Specified Tolerable Error,the Average for Charac-teristic of a Lot or Process4E 337 Test Method for Measuring Humidity with a Psy-chrometer(the Measurement of Wet-and Dry-Bulb Tem-peratures)53.Terminology3.1 Definitions:3.1.1 surface resistivitythe surface resistivity of a materialis the ratio of the potential gradient parallel to the current alongits surface to the current per unit width of the surface.Surfaceresistivity of a material is numerically equal to the surfaceresistance between two electrodes forming opposite sides of asquare.The size of the square is immaterial.3.1.2 volume resistivitythe volume resistivity of a mate-rial is the ratio of the potential gradient parallel to the currentin the material to the current density.4.Summary of Test Method4.1 A paper specimen is placed between appropriate metalelectrodes.An electrical voltage is applied for a fixed period oftime and the resultant current between two electrodes ismeasured accurately.By using appropriate electrodes,surfaceand volume resistance may be measured separately.From thisinformation,a calculation of both surface and volume resistiv-ity can be made.5.Significance and Use5.1 Paper generally is considered to be a material havinggood electrical insulating characteristics;for example,rela-tively high resistivity when dry.However,in certain applica-tions,control of electrical resistivity to within specified limitsis an important function,and resistivity measurement tech-niques are required.5.2 While it is possible to measure resistivity using a varietyof instruments(Test Methods D 257),this test method isspecific for the Keithley Model 6105 resistivity adapter.6Theprecision statement was based on the use of that instrument.Studies have shown that results will vary depending upon thetype of resistivity adapter used and if reproducibility betweendifferent instruments in the same laboratory or between differ-ent laboratories is to be achieved,it is essential that the samemodel resistivity adapter be used in each determination.5.3 The power supply and electrometer referred to in thismethod are manufactured by Keithley and the procedure1This test method is under the jurisdiction of ASTM Committee D06 on Paperand Paper Products and is the direct responsibility of Subcommittee D06.92 on TestMethods.Current edition approved April 15,1994.Published June 1994.Originallyapproved in 1989.Last previous edition approved in 1989 as D 4949 89.2Annual Book of ASTM Standards,Vol 10.01.3Annual Book of ASTM Standards,Vol 15.09.4Annual Book of ASTM Standards,Vol 14.02.5Annual Book of ASTM Standards,Vol 11.03.6Manufactured by Keithley Instruments,Inc.,28775Aurora Rd.,Cleveland,OH44139.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.describes their use.It is believed that comparable equipmentmanufactured by others would serve the same purpose.Theprecision statement was developed with Keithley equipment.5.4 The control of resistivity is of special importance onhigh-speed nonimpact printing machines where that character-istic will affect printing,machine feeding and handling,orboth.Resistivity is important in the image transfer function ofa nonimpact