ASTM D4672-00
(Test Method)Standard Test Methods for Polyurethane Raw Materials Determination of Water Content of Polyols
Standard Test Methods for Polyurethane Raw Materials Determination of Water Content of Polyols
SCOPE
1.1 These test methods measure water content of polyols and many other organic compounds.
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 This standard does not purport to address all of the safety concerns, 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--ISO Standard 14897 is equivalent to these test methods.
General Information
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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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:D4672–00
Standard Test Methods for
Polyurethane Raw Materials: Determination of Water
1
Content of Polyols
This standard is issued under the fixed designation D 4672; 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 4. Summary of Test Methods
1.1 These test methods measure water content of polyols 4.1 Test MethodsAand B are based essentially on volumet-
and many other organic compounds. ric or coulometric titrations that follow the reduction of iodine
1.2 The values stated in SI units are to be regarded as the by sulfur dioxide in the presence of water. This reaction
standard. The values given in parentheses are for information proceeds quantitatively when methanol or another alcohol
only. (ROH) and pyridine (C H N) or a similar amine (R8N) are
5 5
1.3 This standard does not purport to address all of the present to react with the sulfur trioxide (SO ) and hydriodic
3
safety concerns, if any, associated with its use. It is the acid (HI) produced according to the following reactions:
responsibility of the user of this standard to establish appro- ROH+SO +R8N→ [R8NH]SO R
2 3
priate safety and health practices and determine the applica- H O+I +[R8NH]SO R+2R8N→ [R8NH]SO R + 2[R8NH]I
2 2 3 4
bility of regulatory limitations prior to use. 4.2 To determine water, Karl Fischer reagent (a solution of
iodine, sulfur dioxide, imidazole, and pyridine or a pyridine
NOTE 1—ISO Standard 14897 is equivalent to these test methods.
substitute) is added to a solution of the sample in methanol or
other alcohol until all the water present has been consumed.
2. Referenced Documents
2 The titrant can either be added by buret (volumetry) or
2.1 ASTM Standards:
generated electrochemically in the titration cell (coulometry).
D 1193 Specification for Reagent Water
Coulometric titrations eliminate the need for standardizing the
D 883 Terminology Relating to Plastics
reagent.
E 180 Practice for Determining the Precision of ASTM
Methods for Analysis and Testing of Industrial and Spe-
5. Significance and Use
cialty Chemicals
5.1 These test methods are suitable for quality control, as a
specification test, and for research. The water content of a
3. Terminology
polyol is important since isocyanates react with water.
3.1 Definition:
3.1.1 polyurethane, n—a polymer prepared by the reaction
TEST METHOD A: MANUAL PROCEDURE
of an organic diisocyanate with compounds containing hy-
NOTE 2—Commercially available automated Karl Fischer titrators are
droxyl groups.
used extensively.
3.1.1.1 Discussion—Polyurethanes, or urethanes, as they
5.2 The description of the manual systems presented below
are sometimes called, may be thermosetting, thermoplastic,
is for reference purposes and has been included in order to
rigid or soft and flexible, cellular or solid. (See Terminology
better define the principles of the Karl Fischer measurement.
D 883.)
6. Apparatus
6.1 Titration Vessel—A vessel of approximately 300-mL
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These test methods are under the jurisdiction of ASTM Committee D20 on
capacity, such as a tall-form, lipless beaker, provided with a
Plastics and are the direct responsibility of Subcommittee D20.22 on Cellular
tight-fitting closure to protect the reaction mixture from atmo-
Plastics. It was recommended to ASTM by the American Plastics Council.
spheric moisture.The vessel shall also be fitted with a nitrogen
Current edition approved Nov. 10, 2000. Published February 2001. Originally
published as D 4672 – 91. Last previous edition D 4672 – 95.
inlet tube, a 10-mLburet, a stirrer (preferably magnetic), and a
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
port that may be opened momentarily for sample and solvent
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
addition or removal of electrodes. It is convenient to provide a
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. vacuum line leading to a 1-L trap bottle for drawing off the
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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.
D4672–00
titrated solution. Pass the nitrogen through a drying tube 8. Sampling
containing anhydrous calcium sulfate before it enters the
8.1 It is essential to avoid changes in the water content of
titration vessel.
the material during sampling operations. Many
...
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