ASTM D871-96(2004)
(Test Method)Standard Test Methods of Testing Cellulose Acetate
Standard Test Methods of Testing Cellulose Acetate
SIGNIFICANCE AND USE
Moisture content of the cellulose ester can be used to estimate the dry weight of the cellulose ester. Since cellulose esters are desiccants, their moisture content can vary greatly depending on storage.
SCOPE
1.1 These test methods cover procedures for testing cellulose acetate.
1.2 The test procedures appear in the following sections:SectionsAsh to Color and Haze to Combined Acetyl or Acetic Acid ContentTest Method A. Solution Method, to Test Method B. Heterogeneous Saponification Method, to Free Acidity to Heat Stability to Hydroxyl Content to Intrinsic Viscosity to Moisture Content to Primary Hydroxyl Content to Sulfur or Sulfate Content to Viscosity to
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 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.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: D871 – 96 (Reapproved 2004)
Standard Test Methods of Testing
Cellulose Acetate
This standard is issued under the fixed designation D871; 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.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope on Cellulose Esters by Potentiometric Titration—
Alternative Method
1.1 These test methods cover procedures for testing cellu-
lose acetate.
3. Purity of Reagents
1.2 The test procedures appear in the following sections:
3.1 Reagent grade chemicals shall be used in all tests.
Sections
Unless otherwise indicated, it is intended that all reagents shall
Ash 8 to 11
Color and Haze 67 to 72
conform to the specifications of the Committee on Analytical
Combined Acetyl or Acetic Acid Content
Reagents of the American Chemical Society, where such
Test Method A. Solution Method 17, 19 to 23
specifications are available. Other grades may be used, pro-
Test Method B. Heterogeneous Saponification Method 17, 24 to 26
Free Acidity 12 to 16
vided it is first ascertained that the reagent is of sufficiently
Heat Stability 47 to 56
high purity to permit its use without lessening the accuracy of
Hydroxyl Content 27 to 33
the determination.
Intrinsic Viscosity 57 to 62
Moisture Content 4 to 7
3.2 Unless otherwise indicated, references to water shall be
Primary Hydroxyl Content 34 to 39
understood to mean reagent tared, low, wide-form weighing
Sulfur or Sulfate Content 40 to 45
bottle and water, conforming to Specification D1193.
Viscosity 63 to 66
1.3 The values stated in SI units are to be regarded as the
MOISTURE CONTENT
standard. The values given in parentheses are for information
4. Significance and Use
only.
1.4 This standard does not purport to address all of the
4.1 Moisture content of the cellulose ester can be used to
safety concerns, if any, associated with its use. It is the
estimate the dry weight of the cellulose ester. Since cellulose
responsibility of the user of this standard to establish appro-
esters are desiccants, their moisture content can vary greatly
priate safety and health practices and determine the applica-
depending on storage.
bility of regulatory limitations prior to use.
5. Procedure
2. Referenced Documents
5.1 Transfer about5gofthe sample to a tared, low,
2.1 ASTM Standards:
wide-form weighing bottle and weigh to the nearest 0.001 g.
D1193 Specification for Reagent Water
Dry in an oven for2hat105 6 3°C. Remove the bottle from
D1343 Test Method for Viscosity of Cellulose Derivatives
the oven, cover, cool in a desiccator, and weigh.
by Ball-Drop Method
6. Calculation
D2929 Test Method for Sulfur Content of Cellulosic Mate-
rials by X-Ray Fluorescence
6.1 Calculate the percentage of moisture as follows:
D5897 Test Method for Determination of Percent Hydroxyl
Moisture, % 5 ~A/B! 3 100
where:
These test methods are under the jurisdiction of ASTM Committee D01 on
Paint and Related Coatings, Materials, and Applications and are the direct
responsibility of Subcommittee D01.36 on Cellulose and Cellulose Derivatives.
Current edition approved June 1, 2004. Published June 2004. Originally
approved in 1946. Last previous edition approved in 1996 as D871 – 96. DOI: Reagent Chemicals, American Chemical Society Specifications, American
10.1520/D0871-96R04. Chemical Society, Washington, DC. For suggestions on the testing of reagents not
For referenced ASTM standards, visit the ASTM website, www.astm.org, or listed by the American Chemical Society, see Analar Standards for Laboratory
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Standards volume information, refer to the standard’s Document Summary page on and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
the ASTM website. MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D871 – 96 (2004)
13.2 Sodium Hydroxide, Standard Solution (0.01 N)—
A = weight loss on heating, g, and
Prepare and standardize a 0.01N solution of sodium hydroxide
B = sample used, g.
(NaOH).
7. Precision and Bias
14. Procedure
7.1 No statement on bias can be made as no reference
14.1 Shake5gofthe sample, ground to pass a No. 20 (850
material is available as a standard.
µm) sieve and corrected for moisture content if necessary, in a
ASH 250-mL Erlenmeyer flask with 150 mL of freshly boiled, cold
water. Stopper the flask and allow it to stand for 3 h. Filter off
8. Significance and Use
the cellulose acetate and wash it with water. Titrate the
8.1 Ash content gives an estimate of the inorganic content combined filtrate and washings with 0.01 N NaOH solution,
using phenolphthalein indicator solution.
of cellulose ester samples. The presence of high levels of
inorganic content (ash) can be detrimental to the melt stability 14.2 Runablankdeterminationonthewater,usingthesame
and optical clarity of a cellulose ester in melt processing or act volume as was used in extracting the sample.
as a potential source of insolubles when the ester is used in
15. Calculation
solution.
15.1 Calculate the percentage of acidity as free acetic acid
9. Procedure
as follows:
9.1 Dry the sample for2hat105 6 3°C and weigh 10 to 50
Free acetic acid, % 5 [~A 2B!N 3 0.06 3 100]/W (1)
g, to the nearest 0.01 to 0.1 g, depending on its ash content and
where:
the accuracy desired. An air-dried sample may be used and
A = NaOH solution used to titrate the sample, mL,
calculated to dry weight using the value for moisture deter-
B = NaOH solution used to titrate the blank, mL,
mined as in Sections 5 and 6. Burn directly over a flame in a
N = normality of the NaOH solution, and
100-mL tared platinum crucible that has been heated to
W = sample used, g.
constant weight and weighed to the nearest 0.1 mg. Add the
sample in portions if more than 10 g is taken. The sample
16. Precision and Bias
should burn gently and the portions should be added as the
16.1 No statement on bias can be made as no reference
flame subsides. Continue heating with a burner only as long as
material is available as a standard.
the residue burns with a flame.Transfer the crucible to a muffle
furnace and heat at 550 to 600°C for 3 h, or longer if required,
COMBINED ACETYL OR ACETIC ACID CONTENT
to burn all the carbon. Allow the crucible to cool and then
17. Scope
transfer it, while still warm, to a desiccator. When the crucible
has cooled to room temperature, weigh accurately to the
17.1 Two test methods are described for determining the
nearest 0.1 mg.
combined acetyl or acetic acid content. The first, described in
Sections 19 to 22, is more precise, but less widely applicable,
10. Calculation
than the method described in Sections 24 to 26.
10.1 Calculate the percentage of ash as follows:
18. Significance and Use
Ash, % 5 ~A/B! 3 100
18.1 Acetyl or acetic acid content is a measure of the
where:
amount of acetic acid esterified onto the cellulose backbone of
A = ash, g, and
the polymer. The amount of substitution of acetate ester has a
B = sample used, g.
very strong effect on the polymer’s solubility and physical
properties.
11. Precision and Bias
Test Method A—Solution Method
11.1 No statement on bias can be made as no reference
material is available as a standard.
19. Apparatus
FREE ACIDITY
19.1 Weighing Bottle, glass-stoppered, 15-mL capacity,
25-mm diameter by 50-mm high.
12. Significance and Use
19.2 Tray,copperoraluminum,approximately136.5mm(5
12.1 Free Acidity is a measure of unesterified organic acid ⁄8 in.) square, containing 25 compartments 25.4 mm (1 in. )
in the ester. The presence of high levels of free acid is
square. Each compartment shall have the correct dimensions to
potentially detrimental to the melt processing of the ester and contain one weighing bottle. The entire tray shall fit inside a
can impact the odor of the ester.
desiccator and should have a basket-type handle to facilitate
the introduction and removal of the tray (convenient but not
13. Reagents
essential).
13.1 Phenolphthalein Indicator Solution (1 g/100 mL)— 19.3 Buret, automatic zero, 35-mL, 25-mL bulb, stem
Dissolve1gof phenolphthalein in 100 mL of ethyl alcohol graduated from 25 to 35 mL in 0.05-ml increments; or pipet,
(95 %). automatic zero, 30-mL, for 1.0 N NaOH solution.
D871 – 96 (2004)
19.4 Buret, automatic zero, 15-mL, 10-mL bulb, stem 21.3.1 Gently rotate the flask by hand to distribute and
graduated from 10 to 15 mL in 0.05-mL increments, for 1 N spread the sample in a thin layer over the bottom of the flask.
H SO .
Add 70 mL of acetone to the flask and swirl gently until the
2 4
19.5 Buret, 5-ml, in 0.01 or 0.1-mL divisions, for back
sample particles are completely wetted and evenly dispersed.
titration with 0.1 N NaOH solution.
Stopper the flask and allow it to stand undisturbed for 10 min.
19.6 Magnetic Stirrer, for single flask.
Carefully add 30 mL of dimethyl sulfoxide from a graduate to
19.7 Magnetic Stirrer, capacity twelve or more flasks.
the flask, pouring the solvent down the sides of the flask to
19.8 Stirring Bars, stainless steel Type 416, length 50 mm,
wash down any sample particles clinging to the side. Stopper
diameter 5 to 6 mm, or equivalent, dimensions not critical.
the flask and allow it to stand with occasional swirling until
solution is complete. Magnetic stirring or gentle mechanical
20. Reagents
agitation that will not splash the solution is recommended.
When solution appears to be complete, add 50 mL of acetone
20.1 Acetone—Add one 30-mL portion of 1.0 N NaOH
and swirl or stir for 5 min. Proceed in accordance with 21.4.
solution to a mixture of 150 mLacetone and 100 mLhot water,
allow to stand with frequent swirling for 30 min, and titrate
21.3.2 Dimethyl sulfoxide is the preferred solvent, but if it
with 1.0 N H SO .Add another 30-mLportion of 1.0 N NaOH
is not available, spread the sample in a thin layer over the
2 4
solution to 100 mLof hot water, allow to stand for 30 min, and
bottom of the flask, add 15 mL of acetone, swirl to wet the
titrate. The difference between the two titrations shall not
particles with acetone, stopper the flask, and allow the mixture
exceed 0.05 mL.
to stand undisturbed for 20 min. Add 75 mL of pyridine
20.2 Dimethyl Sulfoxide.
without shaking or swirling, and allow to stand for 10 min.
20.3 Pyridine.
Heat the solution just to boiling and swirl or stir for 5 min.
20.4 SodiumHydroxideSolution(40g/L)—Dissolve 40 g of
Again heat to boiling and swirl or stir for 10 min. Continue to
sodium hydroxide (NaOH) in water and dilute to 1 L.
heat and stir until the mixture is homogeneous and all large gel
20.5 Sodium Hydroxide, Standard Solution (0.1 N)—
masses are broken down into individual highly swollen par-
Prepare and standardize a 0.1 N solution of NaOH.
ticles. When these highly swollen gel particles are well
20.6 Sulfuric Acid (1.0 N)—Prepare and standardize a 1.0
dispersed and are not fused together in large gel masses, no
N solution of sulfuric acid (H SO ).
2 4
further heating is necessary. Cool the flask, add 30 mL of
20.7 Phenolphthalein Indicator Solution (1 g/100 mL)—
acetone, and swirl or stir for 5 min. Proceed in accordance with
Dissolve1gof phenolphthalein in 100 ml of ethyl alcohol
21.4.
(95 %).
21.4 Add 30 mL of NaOH solution (40 g/L) with constant
swirling or stirring to the solution of the sample and also to the
21. Procedure
blank. Use of a magnetic stirrer is recommended (Note 2). It is
21.1 Dry 1.9 6 0.05 g of the ground well-mixed sample in
absolutely necessary that a finely divided precipitate of regen-
a weighing bottle for2hat105 6 3°C and weigh the dried
erated cellulose, free from lumps, be obtained. Stopper the
sample by difference to the nearest 1 mg into a 500-mL
flask and let the mixture stand with occasional swirling, or stir
wide-mouth Erlenmeyer flask. Prepare a blank by drying
on the magnetic stirring unit. Allow 30 min for saponification
approximately 3.8 g of potassium acid phthalate and weighing
of lower acetyl samples, 2 h for high acetyl samples when
it by difference into a flask as described. Carry the blank
dimethyl sulfoxide is the solvent, and 3 h when pyridine is the
through the entire procedure.
solvent.At the end of the saponification period, add 100 mLof
hot water, washing down the sides of the flask, and stir for 1 or
NOTE 1—Potassium acid phthalate is used so that the concentration of
the NaOH in contact with the solvent in the blank will be approximately
2 min. Add 4 or 5 drops of phenolphthalein indicator solution
the same as that in contact with the sample and so that the titration of the
and titrate the excess NaOH solution with 1.0 N H SO (Note
2 4
blank will be approximately the same as the titration of the sample, thus
3). Titrate rapidly with constant swirling or stirring ring until
avoiding errors caused by using a different buret for the titration of the
the end point is reached; then add an excess of 0.2 or 0.3 mL
blank and the sample or by refilling the 15-mLburet. If desired, however,
of H SO . Allow the mixture to stand with occasional stirring
the potassium acid phthalate may be omitted. 2 4
or preferably stir on the magnetic stirrer for at least 10 min.
21.2 If the acetyl content is 32 to 41 % or the acetic acid
Then add 3 drops of phenolphthalein indicator solution to each
content is 45 to 57 %, put the sample into solution as follows:
flask and titrate the small excess of acid with 0.1 N NaOH
Add 150 mL of acetone and 5 to 10 mL of water and swirl to
solution to a persistent phenolphthalein end point. Take ex-
mix. Stopper the flask and allow it to stand with occasional
treme care to locate this end point; after the sample is titrated
swirling until solution is complete. Solution may be hastened
to a faint pink end point, swirl the mixture vigorously or place
bymagneticstirringorbyanysuitablemechanicalshakingthat
it for a moment on the magnetic stirrer. If the end point fades
will provide a gentle rocking type of agitation to avoid
because of acid soaking from the cellulose, continue the
splashing the solution on the stopper. It is essential that
addition of 0.1 N NaOH solution until a faint persistent end
complete solution be effected. Proceed in accordance with
point remains after vigorous swirling or stirring. Titrate the
21.4.
blank in the same manner as the sample.
21.3 If the acetyl content is 41 to 44.8 % or the acetic acid
content is 57 to 62.5 %, dissolve the sample by
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