ASTM D2572-97

Standard Test Method for Isocyanate Groups in Urethane Materials or Prepolymers

SCOPE
1.1 This test method covers the determination of the isocyanate group (NCO) content of a urethane intermediate or prepolymer.  
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.> For specific hazard statements, see Section 8.

General Information

• Status: Historical
• Publication Date: 09-Nov-1997
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.33 - Polymers and Resins

Relations

• Replaced By: ASTM D2572-97(2003)e1 - Standard Test Method for Isocyanate Groups in Urethane Materials or Prepolymers
• Effective Date: 10-Jul-2003

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact
ASTM International (www.astm.org) for the latest information.
Designation: D 2572 – 97
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
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Isocyanate Groups in Urethane Materials or Prepolymers
This standard is issued under the fixed designation D 2572; 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 6.2 Magnetic Stirrer with TFE-fluorocarbon-covered stir-
ring bar.
1.1 This test method covers the determination of the isocy-
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6.3 Pipet, 25-mL.
anate group (NCO) content of a urethane intermediate or
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6.4 Buret, 50 or 100-mL.
prepolymer.
6.5 Analytical Balance.
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
7. Reagents
responsibility of the user of this standard to establish appro-
7.1 Purity of Reagents—Reagent grade chemicals shall be
priate safety and health practices and determine the applica-
used in all tests unless otherwise specified. Unless otherwise
bility of regulatory limitations prior to use. For specific hazard
indicated, it is intended that all reagents shall conform to the
statements, see Section 8.
specifications of the Committee on Analytical Reagents of the
2. Referenced Documents American Chemical Society, where such specifications are
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available. Other grades may be used, provided that it is first
2.1 ASTM Standards:
2
ascertained that the reagent is of sufficiently high purity to
D 841 Specification for Nitration Grade Toluene
permit its use without lessening the accuracy of the determi-
3. Summary of Test Method
nation.
7.2 Bromphenol Blue Indicator, prepare solution 0.1% by
3.1 The urethane prepolymer is allowed to react with an
mixing 0.10 g of acid, nonwater soluble bromphenol blue with
excess of di-n-butylamine in toluene (Note 1). After the
1.5 mL of 0.1 N sodium hydroxide solution and diluting to 100
reaction is complete, the excess of di-n-butylamine is deter-
mL with distilled water.
mined by back titration with standard hydrochloric acid.
7.3 Di-n-butylamine Solution, 0.1 N in dry toluene. Not
NOTE 1—Solvents other than toluene may be needed in some cases, for
standardized.
example, anhydrous dimethylformamide (DMF), but the procedure has
7.4 Hydrochloric Acid Solution, 0.1 N standardized using
not been evaluated using them.
bromphenol blue indicator solution.
7.5 Isopropyl Alcohol.
4. Significance and Use
7.6 Toluene, anhydrous, conforming to Specification D 841
4.1 The percent NCO is used to establish unit ratios for
or equivalent dried with molecular sieve pellets.
stoichiometric reactions with co-reactants.
8. Hazards
5. Interferences
8.1 Diisocyanates are strong skin irritants and sensitizers.
5.1 Phosgene, the carbamyl chloride of isocyanate, hydro-
They are also hazardous to the lungs. (TLV for toluene 2,4-
gen chloride, or any other acidic or basic impurities of
diisocyanate is 0.005 ppm.) Avoid contact with skin, eyes, and
sufficient strength will interfere. The concentration of these
clothing, and avoid breathing these substances. Use with
compounds is usually sufficiently low that their effect on the
adequate ventilation. In case of contact, wash with plenty of
determination is negligible.
water and flush eyes for 15 min. Call a physician before reuse.
6. Apparatus See Supplier’s Material Safety Data Sheet for additional
information.
6.1 Polyethylene Stoppers (or corks) covered with alumi-
num foil to fit 250-mL Erlenmeyer flasks.
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Burets and pipets shall conform to National Institute of Standards and
Technology tolerances.
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This test method is under the jurisdiction of ASTM Committee D-1 on Paint Reagent Chemicals, American Chemical Society Specifications, American
and Related Coatings, Materials, and Applications and is the direct responsibility of
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
Subcommittee D01.33 on Polymers and Resins. listed by the American Chemical Society, see Analar Standards for Laboratory
Current edition approved Nov. 10, 1997. Published June 1998. Originally Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
published as D 2572 – 67 T. Last previous edition D 2572 – 91. and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
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Annual Book of ASTM Standards, Vol 06.04. MD.
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NOTICE:¬This¬standard¬has¬either¬been¬superceded¬and¬replaced¬by¬a¬new¬version¬or¬discontinued.¬
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