ASTM D5897-96

Standard Test Method for Determination of Percent Hydroxyl on Cellulose Esters by Potentiometric Titration—Alternative Method

SCOPE
1.1 This test method covers a procedure for determining the percent hydroxyl on cellulose esters by potentiometric titration. The typical range of percent hydroxyl measured is 0.7 to 10.0%.

General Information

• Status: Historical
• Publication Date: 09-Jan-1996
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.36 - Cellulose and Cellulose Derivatives

Relations

• Replaced By: ASTM D5897-96(2001) - Standard Test Method for Determination of Percent Hydroxyl on Cellulose Esters by Potentiometric Titration—Alternative Method
• Effective Date: 10-Jan-1996
• Referred By: ASTM D817-12(2019) - Standard Test Methods of Testing Cellulose Acetate Propionate and Cellulose Acetate Butyrate
• Effective Date: 10-Jan-1996
• Referred By: ASTM D871-96(2019) - Standard Test Methods of Testing Cellulose Acetate
• Effective Date: 10-Jan-1996

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 5897 – 96
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
Determination of Percent Hydroxyl on Cellulose Esters by
Potentiometric Titration—Alternative Method
This standard is issued under the fixed designation D 5897; 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 prevent erroneous results from material that may have refluxed
into the joint.
1.1 This test method covers a procedure for determining the
percent hydroxyl on cellulose esters by potentiometric titration.
6. Apparatus
The typical range of percent hydroxyl measured is 0.7 to
6.1 Titrator, equipped with Glass Electrode, or equivalent.
10.0 %.
6.2 Heating/Stirring Module, six-place.
2. Referenced Documents 6.3 Heating/Stirring Block, cut from polished-finish alumi-
num block to fit stirrer in 7.2 (see Fig. 1 for dimensions).
2.1 ASTM Standards:
6.4 Stirrer, six place.
D 817 Test Methods of Testing Cellulose Acetate Propi-
6.5 Magnetic Stirrers, size 25 mm and 50 mm.
onate and Cellulose Acetate Butyrate
2 6.6 Stirring Bar.
D 871 Test Methods of Testing Cellulose Acetate
6.7 Flask and Air Condenser, (see Fig. 2 for dimensions).
3. Summary of Test Method 6.8 Bottle-Top Dispensers, capable of dispensing 20 mL, 35
mL, and 50 mL, or equivalent.
3.1 The cellulose ester is dissolved in pyridine and the
6.9 Analytical Balance, capable of weighing 250 g to the
hydroxyl sites on the cellulose ester are acetylated with acetic
fourth decimal place.
anhydride in the presence of basic catalyst, 1-methylimidazole.
6.10 Analytical Balance, capable of weighing 1000 g to the
The excess acetic anhydride is hydrolyzed and the resulting
second decimal place.
acetic acid is titrated with sodium hydroxide. An automatic
titrator dispenses the titrant, potentiometrically determines the
7. Reagents and Materials
endpoint, and calculates the percent hydroxyl on the cellulose
7.1 Purity of Reagents—American Chemical Society re-
ester based on a blank determination.
agent grade chemicals shall be used throughout this test unless
4. Significance and Use
otherwise indicated.
7.2 Pyridine.
4.1 This test method provides a simpler means for the
7.3 Acetic Anhydride.
determination of the hydroxyl content of cellulose esters than
7.4 Acetylating Solution—115 6 0.50 g of acetic anhydride
the preparation and measurement of the carbanilate derivative
per litre of pyridine. The container needs to be equipped with
described in Test Methods D 817 and D 871.
20-mL buret. The shelf-life of this solution is 5 days.
4.2 The hydroxyl content is an important indicator of
7.5 Dimethylformamide.
solubility and reactivity.
7.6 Deionized Water, purified to 18.3 MV resistance.
5. Interferences
7.7 Hydrolyzing Solution—Mix 600 mL dimethylforma-
mide, 300 mL pyridine, and 100 mL water in a 1-L bottle
5.1 Undissolved ester may accumulate on the sides of the
equipped with a bottle top dispenser capable of dosing 35 mL.
flask and on top of the stirring-star during dissolution, leading
Stir for at least 10 min prior to use. The shelf-life of this
to low results. Gently swirling the solution during titration can
solution is 1 month.
reduce this problem.
5.2 The ground glass joints of the flask and the air con-
denser must always be rinsed into the flask with hydrolyzing
Titrator and instruction manual such as Mettler DL77 equipped with DG-
solution at the point of hydrolysis and before titration. This will
115-SC glass electrode available from Mettler Toledo Inc., 69 Princeton-
Hightestown, P.O. Box 71, Hightestown, NJ 08520 has been found suitable for this
purpose.
Reagent Chemicals, American Chemical Society Specifications, American
This test method is under the jurisdiction of ASTM Committee D-1 on Paint Chemical Society, Washington, DC. For suggestions on the testing of reagents not
and Related Coatings, Materials, and Applications and is the direct responsibility of listed by the American Chemical Society, see Analar Standards for Laboratory
Subcommittee D01.36 on Cellulose and Cellulose Derivatives. Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Current edition approved Jan. 10, 1996. Published March 1996. and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
Annual Book of ASTM Standards, Vol 06.03. MD.
D 5897
FIG. 1 Heating/Stirring Block Dimensions
7.8 1-Methylimidazole.
7.9 Sucrose.
7.10 Acetone.
7.11 Potassium Acid Phthalate (KHP), National Institute of
Standards and Technology primary standard grade. Store in
desiccator, after drying for1hat 105°C (65°C).
7.12 Methanol.
7.13 Sodium Hydroxide, 0.5 N in methanol. This solution
has a shelf life of 2 weeks.
7.14 Traceable Buffers, pH 4 and pH 7, available from
National Institute of Standards and Technology.
7.15 Potassium Chloride (KCl),5 M, weigh 37.3 g
(60.3000 g) of KCl into a 100-mL volumetric flask. Dilute to
the mark with purified water. Shake into solution.
7.16 1,2-Dichloroethane.
8. Calibration and Standardization
8.1 Calibration of the Electrode:
NOTE 1—If the electrode is new, perforate the nipple on the rubber cap
and soak the electrode in 5 M potassium chloride for 1 h. Store in pH 4
buffer until use.
8.1.1 Select from the titrator menu the procedure for cali-
bration of the electrode.
8.1.2 Add about 50 mL of pH 4 buffer into a titration cup
and lower the electrode into it.
FIG. 2 Flask and Air Condensor Dimensions
8.1.3 Run the procedure for the titrator to read the correct
pH.
W 3 1000
8.1.4 Repeat process 9.1.1-9.1.3 for buffer pH 7.
N 5 (1)
mL 3 204.23
8.1.5 Make sure that the calibration is done when a new
electrode is put into use and then check once/month thereafter
where:
or when a problem is suspected.
W 5 weight of KHP in g,
8.2 Standardization of Methanolic 0.5 N Sodium Hydroxide:
mL 5 volume of titrant used for titration, and
8.2.1 Weigh approximately 1.5 6 0.1000 g of KHP into a
204.23 5 formula weight of KHP.
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