1、Designation: D1652 11Standard Test Method forEpoxy Content of Epoxy Resins1This standard is issued under the fixed designation D1652; 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 parenthese
2、s indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This test method covers the procedure for manual andautomatic titration o
3、f epoxy resins for the quantitative deter-mination of the percent epoxide content from 0.1 26 %epoxide.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns,
4、 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. For specific hazardstatements, see Section 6.2. Referenced Documents2.1 ASTM Standards
5、:2D1193 Specification for Reagent Water2.2 Other Documents:OSHA Regulations, 29 CFR paragraphs 1910.1000 and1910.120033. Summary of Test Method3.1 The resin is dissolved in a suitable solvent and theresulting solution is titrated with hydrogen bromide eitherdirectly or in situ. The hydrogen bromide
6、reacts stoichiometri-cally with epoxy groups to form bromohydrins; therefore, thequantity of acid consumed is a measure of the epoxy content.3.1.1 In the Manual Titration Method, the titration is withstandard perchloric acid in the presence of an excess oftetraethylammonium bromide. Hydrogen bromide
7、 generated insitu by the addition of perchloric acid to the quaternaryammonium halide rapidly opens the oxirane ring.3.1.2 In the Automatic Titration Method, the reaction ismeasuring the millivolt (MV) potential as perchloric acid isadded, which combines with the bromide to form the hydro-bromic aci
8、d, which reacts with the epoxide group. As thereaction progresses, the potential will gradually increase untilthe reaction nears completion at which point the potentialincreases very quickly. The titrator measures the rate of thereaction by calculating the change in potential between per-chloric aci
9、d addition increments. When the change in potentialbegins to decrease, the titrator determines that the titration iscomplete. The epoxide content is calculated using the reagentfactor entered by the user during standardization, the weight ofthe sample, and the volume of perchloric acid added duringt
10、itration.4. Significance and Use4.1 The epoxy content of epoxy resins is an importantvariable in determining their reactivity and the properties ofcoatings made from them. These test methods may be used todetermine the epoxy content of manufactured epoxy resins andconfirm the stated epoxy content of
11、 purchased epoxy resins.5. Reagents5.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specificati
12、ons are available.4Other grades may beused, provided it is first ascertained that the reagent is of1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.33 on Polymers and Resins
13、.Current edition approved Nov. 1, 2011. Published January 2012. Originallyapproved in 1969. Last previous edition approved in 2004 as D1652 04. DOI:10.1520/D1652-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Bo
14、ok of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from U.S. Government Printing Office Superintendent of Documents,732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:/www.access.gpo.gov.4Reagent Chemicals, American Chem
15、ical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Ph
16、armacopeial Convention, Inc. (USPC), Rockville,MD.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.sufficiently high purity to permit its use without lessening theaccur
17、acy of the determination.5.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Type II of Specification D1193.6. Hazards6.1 Hydrogen bromide and glacial acetic acid are corrosive.Chlorobenzene and chloroform are considered hazardous.
18、 Inaddition to other precautions, take care to avoid inhalation andskin or eye contact with these chemicals. Use goggles or a faceshield, or both. Protect skin by use of suitable protectiveclothing. All specimen preparations shall be done in a wellventilated area, such as a fume hood.6.2 Consult cur
19、rent OSHA Regulations, Suppliers MaterialSafety Data Sheets, and local regulations for all materials usedin this test method.Manual Titration for Epoxy Content of Epoxy Resins7. Apparatus7.1 Buret, closed-reservoir type, bottom filling, 25-mL with110-mL division, or potentiometric automatic titrator
20、.7.2 Erlenmeyer Flasks, 100-mL, 250-mL, and 500-mL.7.3 Magnetic Stirrer, adjustable speed.7.4 Magnetic Stirring Bars, polytetrafluoroethylene (PTFE)coated.7.5 Pipets:7.5.1 Measuring Pipet, 25-mL.7.5.2 Volumetric Pipet, 50-mL.7.6 Volumetric Flask,1L.7.7 Bottle, 2 oz wide-mouth, or 100-mL disposable b
21、eaker,or equivalent.8. Reagents8.1 Glacial Acetic Acid (WarningSee Section 6).8.2 Tetraethylammonium Bromide, anhydrous crystals.8.3 Perchloric Acid (HClO4), 0.1 N in Glacial Acetic Acid(WarningSee Section 6).8.4 Acetic Anhydride (WarningSee Section 6).8.5 Methylene Chloride (WarningSee Section 6).8
22、.6 Crystal Violet Indicator, crystals.8.7 Potassium Acid Phthalate(KHC8H4O4) primary stan-dard grade.9. Reagent Preparation9.1 Tetraethylammonium Bromide Solution in Glacial Ace-tic Acid (WarningSee Section 6):9.1.1 Dissolve, with agitation at room temperature, 100 g oftetraethylammonium bromide in
23、400 mL of glacial acetic acid.9.2 Crystal Violet Indicator SolutionPrepare 0.1 % solu-tion of crystal violet indicator in glacial acetic acid(WarningsSee Section 6).10. Standardization of 0.1 N Perchloric Acid Reagent10.1 Standardization with Potassium Acid Phthalate:10.1.1 Dissolve 0.4 g of potassi
24、um acid phthalate, weighedaccurately to the nearest milligram, in 50 mL of glacial aceticacid, and add 6 to 8 drops of crystal violet indicator solution.Insert a clean stirring bar into the sample, and adjust themagnetic stirrer to effect solution. Continue agitation through-out the titration proced
25、ure. Titrate with perchloric acid reagentsolution to the end point, which is a sharp change in color fromblue to green, stabilize for at least 2 min.10.1.2 Calculate and record the perchloric acid reagentnormality as follows:N 5 W 3 1000!/204.2 3 V! (1)where:N = normality of perchloric acid reagent,
26、W = potassium acid phthalate used, g, andV = volume of perchloric acid reagent required to titratethe standard, mL.10.2 Standardization with Potassium Hydrogen Phthalate:10.2.1 Dissolve 0.25 to 0.40 g of the potassium hydrogenphthalate accurately weighed to the nearest milligram into a 2oz wide-mout
27、h bottle or 100 mL disposable beaker. Add 40 to50 mL of glacial acetic acid. Insert a clean stirring bar into thesample and adjust the magnetic stirrer to effect solution.Continue agitation throughout the titration procedure.10.2.2 Add 10 mL of tetraethylammonium bromide reagentand 6 to 8 drops of c
28、rystal violet indicator solution and titrateto a sharp blue-to-green end point with the perchloric acidreagent solution. The end point should be stable for at least 30s.10.2.3 Calculate and record the perchloric acid reagentfactor, F, as follows:F 5 Wd3 E!/V (2)where:Wd= potassium hydrogen phthalate
29、 standard used, g andE = epoxide of the potassium hydrogen phthalate stan-dard used (normally 21.05), weight %.11. Procedure11.1 Weigh the required amount of specimen into a 2-ozdisposable glass bottle or plastic beaker. The amount ofspecimen weight used is dependent on the expected epoxideequivalen
30、t weight (EEW) as follows:EEW Approximate Specimen Size, g170375 0.4375600 0.66001000 0.810001500 1.315002000 1.820002500 2.325005000 2.811.2 Add 10 to 15 mL of methylene chloride to thespecimen. Insert a clean stirring bar and adjust the magneticstirrer to effect solution. Continue agitation throug
31、h the titra-tion procedure.11.3 Add 10 mL of tetraethylammonium bromide reagentand 6 to 8 drops of crystal violet indicator solution. Titrate with0.1 N perchloric acid reagent to a sharp blue to green end pointwhich is stable for at least 30 s. Record the volume ofperchloric acid reagent used to tit
32、rate the specimen.D1652 11212. Calculation12.1 If 10.1 (Standardization of Potassium Acid Phthalate)is used for standardization, calculate weight percent epoxide,E, as follows:E 5 4.3 3 V 3 N/W (3)12.2 If 10.2 (Standardization of Potassium Acid Phthalate)is used for standardization, calculate the we
33、ight percent epox-ide, E, as follows:E 5 F 3 V/We(4)where:We= weight of epoxy resin specimen used, g.12.3 Calculate the epoxy equivalent weight, WEEW,asfollows:WEEW5 43 3 100/E (5)where 43 = mol weight of the epoxy ring.12.4 Calculate weight percent of oxirane oxygen, O,asfollows:O 5 16/43 3 E 5 1.6
34、 3 V 3 N/W (6)13. Precision13.1 A liquid epoxy resin sample with approximately24.1 % epoxide was tested by seven laboratories where tenanalysts obtained the following results:13.1.1 RepeatabilityThe difference between two resultsobtained by the same analyst should not vary by more than1.22 % relativ
35、e.13.1.2 ReproducibilityThe difference between two re-sults, each the mean of two determinations obtained byanalysts in different laboratories should not vary by more than2.97 % relative.Automatic Titration Method14. Apparatus14.1 Automatic Titrator, equipped with a 10 mL burette anda pH electrode.1
36、4.2 A Four Place Analytical Balance.15. Reagents and Materials15.1 Perchloric Acid, 0.1N in glacial acetic acid.15.2 Tetramethyl Ammonium Bromide (TEAB), solution inglacial acetic acid.15.3 Methylene Chloride (MECL).15.4 Potassium Hydrogen Phthalate (KHP).16. Reagent Preparation16.1 Perchloric Acid
37、(0.1 N Solution in Glacial AceticAcid) (WarningSee Section 6.)Prepare in the followingmanner and sequence in order to avoid an excessive rise intemperature.16.1.1 Place approximately 250 mL of glacial acetic acidintoa1Lvolumetric flask. Add 13 mL of 60 % perchloric acidand mix. Add 50 mL of acetic a
38、nhydride, dilute to the markwith glacial acetic acid, and mix thoroughly.16.1.2 Allow to stand at least 8 h for completion of reactionbetween the acetic anhydride and water. A shorter time periodmay be used if completion of the reaction is analyticallyverified.16.2 Tetraethylammonium Bromide Solutio
39、n in Glacial Ace-tic Acid (WarningSee Section 6):16.2.1 Dissolve, with agitation at room temperature, 100 gof tetraethylammonium bromide in 400 mL of glacial aceticacid.17. Standardization of 0.1 N Perchloric Acid Reagent17.1 Standardization with Potassium Acid Phthalate:17.1.1 Dissolve 0.25 g of po
40、tassium acid phthalate, weighedaccurately to the nearest milligram, in 50 mL of glacial aceticacid, and 15 mL 20 % TEAB solution. Titrate with perchloricacid reagent solution.17.1.2 Calculate and record the perchloric acid reagentnormality as follows:N 5 W 3 1000!/204.2 3 V! (7)where:N = normality o
41、f perchloric acid reagent,W = potassium acid phthalate used, g, andV = volume of perchloric acid reagent required to titratethe standard, mL.18. Procedure18.1 Fill burette with 0.1 N perchloric acid solution inglacial acetic acid.18.2 Flush all titrator lines to assure no air bubbles arepresent.18.3
42、 Add the appropriate amount of sample to a sample cup.18.4 Add 30 mL of MECL and 15 mL of TEAB to thesample.18.5 Select the correct method on the titrator and run thesample. The method should prompt when to enter the sampleweight.18.6 The titrator will automatically print out the resultsusing the fo
43、rmula in Section 19.19. Calculation19.1 Calculate:R2 5 R 3 C 3 0.1000/M (8)where:R2 = epoxide content,R = actual mL perchloric acid used to reach equivalencepoint,C = constant of 4.3 (see Note 2), andM = weight of the sample used.NOTE 10.1000 is the normality of the perchloric acid.NOTE 24.3 is the
44、theoretical molecular weight of the epoxide ring, 43,and it is adjusted to 4.3 for the calculation to percent epoxide.20. Precision20.1 An epoxy resin sample, with 5.74 % epoxide, wastested by six laboratories in five different countries for %epoxide content and the following results were obtained:D
45、1652 11320.1.1 RepeatabilityThe difference between two resultsobtained by the same analyst should not vary by more than1.1 % relative.20.1.2 ReproducibilityThe difference between laborato-ries should no vary by more than 0.8 % relative.21. Keywords21.1 epoxide equivalent weight (EEW); liquid epoxy r
46、esin;oxirane; weight percent epoxide; weight per epoxy equivalent(WPE)SUMMARY OF CHANGESCommittee D01 has identified the location of selected changes to this standard since the last issue (D1652 - 04)that may impact the use of this standard. (Approved November 1, 2011.)(1) Updated 8.3.(2) Deleted 9.
47、1, 9.1.1, and 9.1.2 and renumbered subsequentsections.ASTM International takes no position respecting the validity of any patent rights 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 r
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