1、Designation:D546002(Reapproved 2012)Standard Test Method forRubber Compounding MaterialsWater in RubberAdditives1This standard is issued under the fixed designation D5460;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of la
2、st 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 procedure for the determina-tion of water in 2-mercaptobenzothiazole sulfenamide accel-erators by a
3、 Karl Fischer coulometric titration.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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
4、 this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Terminology2.1 Definitions:2.1.1 inert fillerany nonwater soluble additive used as asupport,binder,processing aid,dedustant,etc.,which may beused in the proc
5、ess of manufacture of a rubber additive.2.1.2 lota production quantity representative of a standardproduction unit.2.1.3 test portionthe actual material used in the analysis;it must be representative of the lot(see 2.1.2).3.Summary of Test Method3.1 The sulfenamide is heated in an oven to remove wat
6、er.This water is directed into the titration vessel of a Karl Fischercoulometric titrator with a stream of dry air or nitrogen.Thewater collected in the titration vessel is quantified coulometri-cally.Commercial instrumentation exists to carry out thistwo-step procedure automatically.4.Significance
7、and Use4.1 This test method is designed to determine the watercontentofvariousrubberaccelerators.Since2-mercaptobenzothiazolesulfenamideishydrolyticallyunstable,the residual water content is an important character-istic.5.Interferences5.1 The Karl Fischer titration is inherently unreceptive tothe an
8、alysis of ketones,aldehydes,and amines.The reagentsystems of Section 7 can be used when free amines are presentif benzoic acid is added to the titration vessel before analysis.The acid serves to adjust the apparent pH difficulties when freeamines are present.Add 5 g of benzoic acid to the titrationv
9、essel before starting a series of analyses.This is renewedwhenever a drift value exceeds 30%of the microgram count orwhen a known amount of water does not produce the correctmicrograms count.5.2 Some rubber chemicals contain amines as part of theirstructure and may release these amines during the he
10、atingprocess.6.Apparatus6.1 Karl Fischer Coulometric Apparatus,equipped with aheating oven to remove water from the test portion placed in it.The water is directed into the titration vessel by means of astream of dry air or nitrogen.The evolved water is quantifiedcoulometrically.The instrument must
11、satisfy conditions foundin 6.2 and Section 9.NOTE1The apparatus must be used by those versed in its operation.It is not the intent or purpose of this test method to instruct the operator.This information is best obtained from manuals supplied by the manufac-turers.6.2 Sample Containers,capable of co
12、ntaining 1 to 4 g of atest portion.6.3 Balance,capable of weighing a test portion mass to60.1 mg.6.4 Syringes and Needles,to satisfy the requirements of 8.2.7.Reagents7.1 There are a wide variety of reagents on the market forcoulometric analysis.Use the reagent system(s)recommendedby the manufacture
13、r of the equipment to be used.The systemsmay be of the one component type(same vessel and generator1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.11 on Chemical Analysis.Current edition approved Aug.1,2012.Published Nov
14、ember 2012.Originallyapproved in 1993.Last previous edition approved in 2006 as D5460 02(2006).DOI:10.1520/D5460-02R12.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 solutions)or the two component type(same solution for vesseland generat
15、or).Both systems were used in the results reportedin the Appendix.7.2 Benzoic Acid,reagent grade.7.3 De-Ionized Water and Commercial Water Standards.7.4 Nitrogen,Dry Air or Inert Gas.7.5 Pyridine-Free or Pyridine-Containing Solutions may beused.Pyridine-free solutions were used for the results repor
16、tedin the Appendix.8.Calibration8.1 Karl Fischer coulometric analyzers need no calibration.Operation is based on Faradays Law which states that onecoulomb of electricity is needed to electrolyze one mole of amaterial.8.2 Periodic confirmation of this is obtained by injecting aknown amount of water into the titration vessel.This mustproduce the theoretical g count within reasonable tolerances.As an example:Injection of 2.0 mm3of water should producea g count of 2000 g 6 50 to 100 g.8.3 Water stan