ASTM D1652-97

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D1652–97
Standard Test Methods for
Epoxy Content of Epoxy Resins
This standard is issued under the fixed designation D 1652; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) 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 5. Reagents
5.1 Purity of Reagents—Reagent grade chemicals shall be
1.1 These test methods cover the quantitative determination
of the epoxy content of epoxy resins. used in all tests. Unless otherwise indicated, it is intended that
1.2 This standard does not purport to address all of the all reagents shall conform to the specifications of the Commit-
safety concerns, if any, associated with its use. It is the tee onAnalytical Reagents of theAmerican Chemical Society,
responsibility of the user of this standard to establish appro- where such specifications are available. Other grades may be
priate safety and health practices and determine the applica- used, provided it is first ascertained that the reagent is of
bility of regulatory limitations prior to use. For specific hazard sufficiently high purity to permit its use without lessening the
statements, see Section 6. accuracy of the determination.
5.2 Purity of Water—Unless otherwise indicated, references
2. Referenced Documents
to water shall be understood to mean reagent water as defined
2.1 ASTM Standards: by Type II of Specification D 1193.
D 1193 Specification for Reagent Water
6. Hazards
E 200 Practice for Preparation, Standardization, and Stor-
age of Standard Solutions for Chemical Analysis 6.1 Hydrogen bromide and glacial acetic acid are corrosive.
Chlorobenzene and chloroform are considered hazardous. In
3. Summary of Test Method
addition to other precautions, take care to avoid inhalation and
3.1 The resin is dissolved in a suitable solvent and the
skin or eye contact with these chemicals. Use goggles or a face
resulting solution is titrated with hydrogen bromide either shield, or both. Protect skin by use of suitable protective
directly or in situ. The hydrogen bromide reacts stoichiometri-
clothing. All specimen preparations shall be done in a well
cally with epoxy groups to form bromohydrins; therefore, the ventilated area, such as a fume hood.
quantity of acid consumed is a measure of the epoxy content.
TEST METHOD A
3.1.1 InTestMethodA,thetitrationisdirectwithastandard
solution of hydrogen bromide in glacial acetic acid.
7. Apparatus
3.1.2 In Test Method B, the titration is with standard
7.1 Buret, closed-reservoir type. The buret tip should be
perchloric acid in the presence of an excess of tetraethylam-
fitted with a rubber stopper of proper size to fit the neck of the
monium bromide. Hydrogen bromide generated in situ by the
Erlenmeyer flask and the stopper should have an additional
addition of perchloric acid to the quaternary ammonium halide
small hole to permit escape of replaced air during titration.
rapidly opens the oxirane ring.
7.2 Magnetic Stirrer, adjustable speed.
4. Significance and Use 7.3 Magnetic Stirring Bars, polytetrafluoroethylene (PTFE)
coated.
4.1 The epoxy content of epoxy resins is an important
variable in determining their reactivity and the properties of
8. Reagents and Materials
coatings made from them. These test methods may be used to
8.1 Chlorobenzene (Warning—See Section 6).
determine the epoxy content of manufactured epoxy resins and
8.2 Chloroform-Chlorobenzene Mixture (1+1) (Warning—
confirm the stated epoxy content of purchased epoxy resins.
See Section 6).
ThesetestmethodsareunderthejurisdictionofASTMCommitteeD-1onPaint
and Related Coatings, Materials, and Applications and are the direct responsibility Reagent Chemicals, American Chemical Society Specifications, American
of Subcommittee D01.33 on Polymers and Resins. Chemical Society, Washington, DC. For suggestions on the testing of reagents not
Current edition approved June 10, 1997. Published October 1997. Originally listed by the American Chemical Society, see Analar Standards for Laboratory
published as D 1652 – 59 T. Last previous edition D 1652 – 90 (1996). Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Annual Book of ASTM Standards, Vol 11.01. and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
Annual Book of ASTM Standards, Vol 15.05. MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D1652–97
8.3 Crystal Violet Indicator Solution—Prepare a 0.1 % so- 10.3 Calculate the percent of oxirane oxygen, O, as follows:
lution of crystal violet in glacial acetic acid.
8.4 Glacial Acetic Acid (Warning—See Section 6).
O 5 1.6N~V – B!/W (3)
8.5 Hydrogen Bromide (HBr), anhydrous (Warning—See
10.4 Calculate the weight per epoxy equivalent, WPE, that
Section 6).
is,gramsofresincontaining1gequivalentofepoxygroups,as
8.6 Potassium Acid Phthalate (KHC H O )—Primary Stan-
8 4 4
follows:
dard grade.
WPE 5 1000W/N~V– B! (4)
8.7 Hydrogen Bromide in Acetic Acid, Standard Solu-
tion (0.1 N)(Warning—See Section 6)—Prepare by bubbling
11. Precision
anhydrous HBr at a slow rate through glacial acetic acid until
the desired normality is attained (approximately8gof HBr/L).
11.1 Repeatability—The difference between two results ob-
Standardize each day used against 0.4 g of potassium acid
tainedbythesameanalystwillapproximate0.7 %oftheepoxy
phthalate (KHC H O ) accurately weighed and dissolved by
8 4 4 content of the resin tested. Two such values should be
gently heating in 10 mL of glacial acetic acid.
considered suspect if they differ by more than 2 % absolute.
11.2 Reproducibility—The difference between two results,
NOTE 1—Reagent of 0.1 N concentration has been specified. As
each the mean of two determinations, obtained by analysts in
solutions exceed this concentration they became progressively less stable
(for further information see Practice E 200). different laboratories, will approximate 2 % of the epoxy
content of the resin tested. Two such values should be
9. Procedure
considered suspect if they differ by more than 6 % absolute.
9.1 Use a quantity of specimen that contains 0.001 to
TEST METHOD B
0.002-g equivalents of epoxy groups. Weigh the appropriate
amount,towithin1mg,intoanErlenmeyerflask.Usea50-mL
12. Apparatus
flask for low-molecular-weight resins (liquid grades) and a
125-mL flask for high-molecular-weight resins (solid grades).
12.1 Buret,closed-reservoirtype,bottomfilling,25mLwith
9.2 Dissolve the specimen in a solvent at room temperature. 1
⁄10-mL division, or potentiometric automatic titrator.
Use 10 mL of chlorobenzene for liquid grade resins or 25 mL
12.2 Erlenmeyer Flasks, 100-mL, 250-mL, and 500-mL.
of a 1+1 mixture of chloroform and chlorobenzene for solid
12.3 Magnetic Stirrer, adjustable speed.
grade resins. Place a magnetic stirring bar into the flask and
12.4 Magnetic Stirring Bars, polytetrafluoroethylene
mix on the magnetic stirrer to dissolve.
(PTFE) coated.
9.3 Add 4 to 6 drops of crystal violet indicator solution and
12.5 Pipets:
attachtheflasktotherubberstopperontheburettip.Lowerthe
12.5.1 Measuring Pipet, 25-mL.
buret tip to a point just above the solution and titrate with the
12.5.2 Volumetric Pipet, 50-mL.
hydrogen bromide in acetic acid solution to a blue-green end
12.6 Volumetric Flask,1L.
point with the magnetic stirrer
...