ASTM D4662-98
(Test Method)Standard Test Methods for Polyurethane Raw Materials Determination of Acid and Alkalinity Numbers of Polyols
Standard Test Methods for Polyurethane Raw Materials Determination of Acid and Alkalinity Numbers of Polyols
SCOPE
1.1 These test methods measure the acidic and basic constituents in polyols and other materials that are soluble in mixtures of toluene and ethyl alcohol. These test methods do not apply to polyethers. (See Note 1.)
1.2 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Note 1-There is no equivalent ISO standard.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
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Designation: D 4662 – 98
Standard Test Methods for
Polyurethane Raw Materials: Determination of Acid and
Alkalinity Numbers of Polyols
This standard is issued under the fixed designation D 4662; 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.
1. Scope * 5. Significance and Use
1.1 These test methods measure the acidic and basic con- 5.1 These test methods are suitable for quality control, as
stituents in polyols and other materials of high acidity or specification tests, and for research. The acid and alkalinity
alkalinity that are soluble in mixtures of toluene and ethyl numbers indicate the extent of a reaction with acids. The results
alcohol. These test methods do not apply to polyethers. (See are measures of batch-to-batch uniformity and may be used as
Note 1.) correction factors in calculating hydroxyl number.
1.2 This standard does not purport to address all of the
6. Reagents and Materials
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 6.1 Purity of Reagents—Use reagent-grade chemicals in all
tests. Unless otherwise indicated, it is intended that all reagents
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. conform to the specifications of the Committee on Analytical
Reagents of the American Chemical Society where such
NOTE 1—There is no equivalent ISO standard.
specifications are available. Other grades may be used pro-
vided it is first ascertained that the reagent is of sufficiently
2. Referenced Documents
high purity to permit its use without lessening the accuracy of
2.1 ASTM Standards:
the determination.
D 883 Terminology Relating to Plastics
6.2 Purity of Water—Unless otherwise indicated, references
D 1193 Specification for Reagent Water
to water shall be understood to mean reagent water as defined
by Type I of Specification D 1193.
3. Terminology
6.3 Ethyl Alcohol, 95 %.
3.1 Definitions—For definitions of terms used in these test
6.4 Hydrochloric Acid (0.1 N)—Prepare a 0.1 N solution of
methods see Terminology D 883.
hydrochloric acid (HCl). Standardization is unnecessary.
3.2 Descriptions of Terms Specific to This Standard:
6.5 Phenolphthalein Indicator Solution—Dissolve 0.5 g of
3.2.1 acid number—the quantity of base, expressed in
phenolphthalein in 100 mL of a mixture of equal volumes of
milligrams of potassium hydroxide, that is required to titrate
water and ethyl alcohol. Add a slight excess of 0.1 N NaOH
acidic constituents present in1gof sample.
solution (pink color) and then just neutralize (colorless) with
3.2.2 alkalinity number—the quantity of base, expressed as
0.1 N HCl.
milligrams of potassium hydroxide, present in1gof sample.
6.6 Potassium Hydroxide, Standard Alcoholic Solution (0.1
N)—Dissolve 5.61 g of potassium hydroxide (KOH) in 10 mL
4. Summary of Test Method
of carbon dioxide-free water and dilute to 1 L with ethyl
4.1 The sample is dissolved in a mixture of toluene and
alcohol. Store the solution in a chemical-resistant dispensing
ethyl alcohol. The resulting single-phase solution is titrated at
bottle protected by a guard tube containing soda-lime or
room temperature with alcoholic potassium hydroxide solu-
soda-asbestos (ascarite). Standardize frequently enough to
tion, to the end point indicated by the color change of the added
detect changes of 0.0005 N, preferably against pure potassium
phenolphthalein. Alkalinity numbers are determined by back-
acid phthalate (KHC H O , 0.8 to 0.9 g) in about 100 mL of
8 4 4
titration after adding excess hydrochloric acid. The endpoint of
carbon dioxide-free water, using phenolphthalein to detect the
these titrations also can be determined potentiometrically.
end point.
These test methods are under the jurisdiction of ASTM Committee D-20 on
Plastics and are the direct responsibility of Subcommittee D20.22 on Cellular Reagent Chemicals, American Chemical Society Specifications, American
Plastics. Chemical Society, Washington, DC. For suggestions on the testing of reagents not
Current edition approved Nov. 10, 1998. Published January 1999. Originally listed by the American Chemical Society, see Analar Standards for Laboratory
published as D 4662 – 87. Last previous edition D 4662 – 93. Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Annual Book of ASTM Standards, Vol 08.01. and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
Annual Book of ASTM Standards, Vol 11.01. MD.
*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.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 4662
6.7 Sodium Hydroxide, Standard Solution (0.1 N)—Prepare TEST METHOD B—ALKALINITY NUMBER
and standardize a 0.1 N solution of sodium hydroxide (NaOH).
10. Procedure
6.8 Titration Solvent—Mix equal volumes of toluene and
ethyl alcohol.
10.1 Proceed as directed in Section 8. If the sample solution
is alkaline to phenolphthalein, add 0.1 N HCl from a 10-mL
7. Sampling
buret until the solution is colorless; then add 1.0 mL excess.
7.1 Polyesters usually contain molecules covering an appre-
Back-titrate to the end point with 0.1 N NaOH solution from a
ciable range of molecular weights. These have a tendency to
10-mL buret. Titrate a blank containing the same amount of
fractionate during solidification. Unless the mate
...
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