ASTM D3644-15(2022)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D3644 − 15 (Reapproved 2022)
Standard Test Method for
Acid Number of Styrene-Maleic Anhydride Resins
This standard is issued under the fixed designation D3644; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 4.2 Because some of the anhydride functionality has been
hydrolyzed in the manufacturing process, direct titration with
1.1 This test method covers the measurement of the free
base will produce erroneous data on the total acid content of
acidity present in styrene-maleic anhydride resins.
the fully hydrolyzed resin in use. This test method charges
1.2 The values stated in SI units are to be regarded as
excess alkali to hydrolize the anhydride functionality and
standard. No other units of measurement are included in this
neutralize the resulting acid. The remaining unreacted alkali is
standard.
thenbacktitratedwithastandardizedacidsolutionandtheacid
1.3 This standard does not purport to address all of the content is determined by difference.
safety concerns, if any, associated with its use. It is the
5. Reagents and Materials
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
5.1 Purity of Reagents—Reagent grade chemicals shall be
mine the applicability of regulatory limitations prior to use.
used in all tests. Unless otherwise indicated, it is intended that
1.4 This international standard was developed in accor-
all reagents shall conform to the specifications of the Commit-
dance with internationally recognized principles on standard-
tee onAnalytical Reagents of theAmerican Chemical Society,
ization established in the Decision on Principles for the
where such specifications are available. Other grades may be
Development of International Standards, Guides and Recom-
used, provided it is first ascertained that the reagent is of
mendations issued by the World Trade Organization Technical
sufficiently high purity to permit its use without lessening the
Barriers to Trade (TBT) Committee.
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 conforming
2.1 ASTM Standards:
to Specification D1193.
D329 Specification for Acetone
5.3 Acetone, conforming to the requirements described in
D1193 Specification for Reagent Water
Specification D329.
3. Terminology
5.4 Phenolphthalein Indicator Solution (20 g/L)—Dissolve
10 g of phenolphthalein in 100 mL of acetone.
3.1 Definitions:
3.1.1 acid number—the number of milligrams of potassium
5.5 Sodium Hydroxide, Standard Solution (0.1 N)—
hydroxide (KOH) required to neutralize the alkali-reactive
Dissolve7gof sodium hydroxide (NaOH) in 7 mL of water,
groups in1gof material under the conditions of test.
and filter the resulting solution through a glass mat in a Gooch
crucible with the aid of suction. Do not wash the residue.
4. Significance and Use
Dilute two thirds of the clear filtrate to 1 L with freshly boiled
4.1 This test method is used to determine the property of
water. Standardize against National Institute of Standards and
styrene-maleic anhydride resins functionality.Acid functional-
Technology standard sample of acid potassium phthalate No.
ity determines the utility of resin as well as being a significant
84, using phenolphthalein as the indicator. Do not adjust the
quality control test.
concentration of the solution, but calculate the normality.
5.6 Sulfuric Acid, Standard Solution (0.1 N)—Measure out
1 3mLofconcentratedsulfuricacid(H SO )(d = 1.84)andpour
ThistestmethodisunderthejurisdictionofASTMCommitteeD21onPolishes 2 4
and is the direct responsibility of Subcommittee D21.02 on Raw Materials.
Current edition approved Dec. 1, 2022. Published December 2022. Originally
approved in 1983. Last previous edition
...