1、Designation: D5376 06 (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
2、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-ge
3、n content of polymerized 2,2,4-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
4、.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
5、-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 s
6、ample 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.
7、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 i
8、s 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
9、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 t
10、he 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. A
11、pparatus7.1 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,5c
12、m3.7.6 Buret,25cm3, Class A, graduated in 0.1 cm3incre-ments.7.7 Buret,50cm3, Class A, graduated in 0.1 cm3incre-ments.7.8 Magnetic Stirrer.7.9 Erlenmeyer Flask, 300 cm3narrow-neck.1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommi
13、ttee 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 a
14、t serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7.10 Measuring Cylinder,50cm3.7.11 Beaker, 150 cm
15、3.7.12 Beaker, 400 cm3.7.13 Dropping Funnel,50cm3.7.14 Thermometer, range 20 to +60C.7.15 Pipet,5cm3.7.16 Volumetric Flask,2dm3.8. Reagents8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specification
16、s 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 A
17、cid, p.a.8.3 Acetic Anhydride, p.a.8.4 Acetone, p.a.8.5 Lithium Perchlorate,3H2O 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 Perchloric acid (70 to 72 %
18、) is a strong oxidant. Caremust be exercised to keep it from contacting organic matter.Seventy to 72 % perchloric acid must be kept at or below roomtemperature. When hot and concentrated it is known to beexplosive.9.2 Acetic anhydride is a noxious chemical and corrosive tothe skin. Avoid breathing v
19、apors and use gloves and gogglesfor protection. Acetone is flammable and vapors form explo-sive mixtures. Consult appropriate texts for further informationon the use and disposal of these chemicals.10. Sampling10.1 To ensure sample homogeneity, grind a minimum of10 g of a “lot” sample with a mortar
20、and pestle. Take test unit(0.4 g) from this composite.11. Reagent Preparation and Standardization11.1 As is the case with any titration method, it is extremelyimportant that the titrants are accurately standardized.11.2 Prepare the primary titrant (0.1 N perchloric acid) bydiluting 70 % perchloric a
21、cid with acetic acid, having firsteliminated the water content by reaction with acetic anhydride.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual S
22、tandards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.FIG. 1 1(a) 2,2-bis (4*-amino-phenyl)-propaneFIG. 2 1(b) (Top)3(4*-amino-phenyl)-terminated oligomeric2,2,4-trimethyl-1,
23、2-dihydroquinoline;(Bottom)6-(4*-amino-phenyl)-terminated oligomeric 2,2,4-trimethyl-1,2-dihydroquinolineFIG. 3 Titration VesselD5376 06 (2012)211.2.1 The exact concentration of the approximately 70 %perchloric acid is determined as follows: weigh about3goftheapproximately 70 % perchloric acid to th
24、e nearest 0.1 mg in aweighing pipet, dissolve in 50 cm3water and titrate with 1 NNaOH using phenolphthalein as indicator. Determine theconcentration of perchloric acid as follows:C15V 3 N 3 MW31001000(1)where:C1= % concentration of perchloric acid,V = volume of NaOH, cm3,N = normality of the NaOH so
25、lution,M = molecular mass of perchloric acid, 100.5, andW = sample mass of approximately 70 % perchloric acid,g.11.2.2 To prepare 2 dm3of 0.1 N perchloric acid solution inacetic acid, the mass (W1) of perchloric acid to be taken is:W152 3 10.05 3 100C1(2)where:W1= mass of perchloric acid, g, andC1=
26、% concentration of perchloric acid from 11.2.1.11.2.2.1 The amount of acetic anhydride (W2) required toeliminate the water content in W1g of perchloric acid iscalculated thus:W25100 2 C1! 3 10.05 3 2 3 100 3 MaC13 18 3 C2(3)where:Ma = molecular mass of acetic anhydride = 102,C1= % concentration of p
27、erchloric acid, andC2= % concentration of acetic anhydride.11.2.3 Add 8.5 cm3of 70 to 72 % perchloric acid to 100 to200 cm3glacial acetic acid. Add 20 cm3of acetic anhydrideand allow the solution to stand for at least 0.5 h. Dilute to 1dm3with glacial acetic acid. To standardize, weigh to thenearest
28、 0.1 mg, about 0.4 g of potassium hydrogen phthalate,dissolve completely in 50 cm3acetone and titrate potentio-metrically with perchloric acid.11.2.4 These solutions are stable over a long period of time.12. Procedure12.1 Assemble appropriate glassware from Section 7 ac-cording to Fig. 3 and place t
29、his assembly on the magneticstirrer.12.2 Prepare the specimen according to Section 10 andweigh 0.4 g to the nearest 0.1 mg into a 150-cm3beaker,dissolve with 50 cm3of acetone and titrate potentiometricallywith 0.1 N perchloric acid using a 25 cm3buret as illustrated inFig. 3.12.3 Determine the blank
30、 value of the solvent following thesame procedure.NOTE 1The water introduced with the perchloric acid is removed byadding a calculated amount of acetic anhydride to combine with the water.The acid-catalyzed reaction of acetic anhydride with water is fairly rapid.When titrating a primary or secondary
31、 amine that might react with aceticanhydride, it is important to avoid any excess acetic anhydride in thetitrant.13. Calculation13.1 Determine the percent total basic nitrogen content asfollows:% nitrogen 5V12 V0! 3 N 3 1410003100S(4)where:V1= volume of perchloric acid required for titration of thes
32、ample, cm3V0= volume of perchloric acid required for blank titration,cm3,N = normality of the perchloric acid solution, andS = specimen mass, g.14. Report14.1 Report the following information:14.1.1 Proper identification of the sample, and14.1.2 Results obtained from the two individual determina-tio
33、ns and their average as percent nitrogen to the nearest 0.1 %.15. Precision and Bias15.1 This precision and bias section has been prepared inaccordance with Practice D4483. Refer to Practice D4483 forterminology and other statistical calculation details.15.2 The precision results in this precision a
34、nd bias sectiongive an estimate of the precision of this test method with thematerials used in the particular interlaboratory programs asdescribed in this section. The precision parameters should notbe used for acceptance or rejection testing of any group ofmaterials without documentation that they
35、are applicable tothose particular materials and the specific testing protocols thatinclude this test method.15.3 A Type 1 (interlaboratory) precision was evaluated in1990. Both repeatability and reproducibility are short term. Aperiod of a few days separates replicate test results.Atest resultis the
36、 mean value of two determinations, as specified by thistest method, of the assay results.15.4 Three sources of TMQ differing slightly in percentnitrogen were analyzed in six laboratories on two differentdays.15.5 The results from one laboratory were eliminated fromthe analysis since they were substa
37、ntially different in valuethan the other five taken as a whole.15.6 The results of the precision calculation for repeatabilityand reproducibility are given in Table 1.15.7 RepeatabilityThe repeatability, r, of this test methodhas been established as the appropriate value in Table 1.Twosingle test re
38、sults, obtained under normal test method proce-dures, that differ by more than the tabulated r (for any givenlevel) must be considered as derived from different or noniden-tical sample populations.15.8 ReproducibilityThe reproducibility, R, of this testmethod has been established as the appropriate
39、value in Table1. Two single test results obtained in two different laboratories,under normal test method procedures, that differ by more thanthe tabulated R (for any given level) must be considered tohave come from different or nonidentical sample populations.15.9 Repeatability and reproducibility e
40、xpressed as a per-cent of the mean level, (r) and (R), have equivalent applicationD5376 06 (2012)3statements as above for r and R. For the (r) and (R) statements,the difference in the two single test results is expressed as apercent of the arithmetic mean of the two test results.15.10 BiasIn test me
41、thod terminology, bias is the differ-ence between an average test value and the reference (or true)test property value. Reference values have not been evaluatedfor this test method. Bias, therefore, cannot be determined.15.11 The full details and test results of the interlaboratorytest program used
42、for this precision section are complete and inthe process of being prepared in the proper format forsubmission as a research report to ASTM.16. Keywords16.1 2,2,4-trimethyl-1,2-dihydroquinoline; antioxidant; ni-trogen; TMQASTM International takes no position respecting the validity of any patent rig
43、hts asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any
44、 time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments wi
45、ll receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by AS
46、TM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); o
47、r through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).TABLE 1 Precision of Percent Nitrogen Analysis for TMQAMaterial AverageWithin Laboratories Between LaboratoriesSr r (r) SR R (R)No. 3 7.30 0.0187
48、0.052 0.71 0.112 0.314 4.30No. 1 7.41 0.0330 0.092 1.24 0.122 0.342 4.62No. 2 7.78 0.0195 0.055 0.71 0.101 0.284 3.65Pooled 7.50 0.0237 0.066 0.87 0.112 0.313 4.19ASr= repeatability standard deviation,r = repeatability = 2.83 times the square root of the repeatability standard deviation,(r) = repeatability (as percent of material average),SR= reproducibility standard deviation,R = reproducibility = 2.83 times the square root of the reproducibility standard deviation, and(R) = reproducibility (as percent of material average).D5376 06 (2012)4
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