ASTM_D_5376_-_06_2012.pdf

Designation:D537606(Reapproved 2012)Standard Test Method forRubber Compounding MaterialsDetermination of the BasicNitrogen Content in Rubber Antioxidant:Polymerized TMQ1This standard is issued under the fixed designation D5376;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 covers the determination of the nitro-gencontentofpolymerized2,2,4-trimethyl-1,2-dihydroquinoline(TMQ).It is based on a potentiometrictitration of an acetone solution of TMQ with perchloric acid inacetic acid.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 this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.Specific precau-tionary statements are given in Section 9.2.Referenced Documents2.1 ASTM Standards:2D4483 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 lot samplea production sample representative of astandard production unit,normally referred to as“the sample.”4.Summary of Test Method4.1 A sample of 2,2,4-trimethyl-1,2-dihydroquinoline(TMQ)is dissolved in acetone and the nitrogen in TMQ isdetermined by a potentiometric titration with perchloric acid inacetic acid.5.Significance and Use5.1 This test method is designed to determine the nitrogencontent of oligomeric 2,2,4-trimethyl-1,2-dihydroquinoline(TMQ)antioxidant.TMQ is used for heat protection ofvulcanized rubber.5.2 This test method is suitable for assessing productspecifications since nitrogen content is related to productperformance,that is,antioxidant efficiency and heat protection.For comparison of product quality at different productionfacilities sufficient interlaboratory accuracy and precision arerequired.6.Interferences6.1 Based on past experience,one significant source of errorin this test method is the titration end point assessment.Problems can be avoided by closely following the procedure.6.2 Theoretically,any material containing basic nitrogen,capable of forming HCl-salt,will be measured by this testmethod.Extensive high performance liquid chromatograph(HPLC)analyses of the product indicates that the mostsignificant interfering impurities are products formed by sidereactions between aniline and acetone,such as those given inFig.1.6.3 Other possible interfering impurities may include theanilino end groups attached to TMQ oligomers,such as thosegiven in Fig.2.7.Apparatus7.1 Standard Laboratory Glassware and Equipment.7.2 Potentiometer.7.3 Reference Electrode,platinum electrode in an electro-lytic glass cell with a frit of porosity 4,filled with a saturatedsolution of lithium perchlorate in acetic acid(see Fig.3).7.4 Glass Electrode.7.5 Weighing Pipet,5 cm3.7.6 Buret,25 cm3,Class A,graduated in 0.1 cm3incre-ments.7.7 Buret,50 cm3,Class A,graduated in 0.1 cm3incre-ments.1This 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 May 1,2012.Published July 2012.Originally approvedin 1993.Last previous edition approved in 2006 as D5376 06.DOI:10.1520/D5376-06R12.2For 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 7.8 Magnetic Stirrer.7.9 Erlenmeyer Flask,300 cm3narrow-neck.7.10 Measuring Cylinder,50 cm3.7.11 Beaker,150 cm3.7.12 Beaker,400 cm3.7.13 Dropping Funnel,50 cm3.7.14 Thermometer,range 20 to+60C.7.15 Pipet,5 cm3.7.16 Volumetric Flask,2 dm3.8.Reagents8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.Unless otherwise indicated,it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.3Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.8.2 Acetic Acid,p.a.8.3 Acetic Anhydride,p.a.8.4 Acetone,p.a.8.5 Lithium Perchlorate,3 H2O p.a.8.6 Perchloric acid,p.a.approx.70%.8.7 Phenolphthalein,1%dissolved in ethanol.8.8 Potassium Hydrogen Phthalate,p.a.8.9 Sodium Hydroxide(1 N)Aqueous sodium hydroxide.9.Hazards9.1 Perchlori