ASTM D817-96(2004)e1
(Test Method)Standard Test Methods of Testing Cellulose Acetate Propionate and Cellulose Acetate Butyrate
Standard Test Methods of Testing Cellulose Acetate Propionate and Cellulose Acetate Butyrate
SIGNIFICANCE AND USE
Ash content gives an estimate of the inorganic content of cellulose ester samples. The presence of high levels of inorganic content (ash) can be detrimental to the melt stability and optical clarity of a cellulose ester in melt processing or act as a potential source of insolubles when the ester is used in solution.
SCOPE
1.1 These test methods cover procedures for the testing of cellulose acetate propionates and acetate butyrates. These esters may vary widely in composition and properties, so certain of the procedures can be used only in the ranges of composition where they are suitable.
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 The test procedures appear in the following sections:
Sections Acetyl Propionyl or Butyryl Contents28-37 Acetyl Content, Apparent18-27 Acidity, Free12-17 Ash 7-10 Color and Haze77-81 Heat Stability57-65 Hydroxyl Content38-44 Hydroxyl Content, Primary46-50 Intrinsic Viscosity67-71 Moisture Content 5-6 Sulfur or Sulfate Content51-56 Viscosity74-75 Limiting Viscosity Number67-71
1.4 This standard does not purport to address 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.
18.1 The test methods described in the following 20 to 26 cover the determination of the saponification value of the sample calculated as percentage of apparent acetyl, equivalent weight 43. This value is required in the calculation of acetyl and propionyl or butyryl contents in 36.1.
18.2 The test method used should be specified or agreed upon. The choice depends on the propionyl or butyryl content and the physical condition of the sample. Ordinarily, Test Method A is recommended for samples having less than about 35 % propionyl or butyryl and Test Method B for samples having more than that amount.
28.1 The test methods described in the following Sections 30 to 36 cover the determination of acetyl and propionyl or butyryl contents of cellulose mixed esters by calculation from the apparent acetyl content, determined in accordance with Sections 18 to 26, and the molar ratio of acetyl and propionyl or butyryl, determined in accordance with Sections 30 to 35. The molar ratio of acetyl and propionyl or butyryl is determined by saponifying, acidifying, vacuum distilling off the mixture of acids, and determining the distribution ratio of the acids between n-butyl acetate and water. The distribution ratios are also determined for acetic, propionic, and butyric acids, using samples of known high purity, and the molar ratio of the acids in the sample is calculated from these values.
28.2 The saponification conditions are varied depending on the propionyl or butyryl content of the sample. Use Procedure A (Section 32) for samples containing less than about 35 % propionyl or butyryl, and use Procedure B (Section 33) for samples containing more than that amount.
28.3 Analyses for combined acetic, propionic, and butyric acids may be done by gas chromatographic methods. Difficulties encountered include ghosting in the columns, variation of factors with composition, and inconsistencies in the use of pure acids as standards. When such methods are used for this purpose, they shall be cross checked with the following partition method using suitable check batches to establish accuracy.
38.1 This test method is applicable to pyridine-soluble cellulose esters and is especially useful when the hydroxyl content is low. (Samples containing plasticizer may be analyzed directly by this test method because the plasticizer is removed during washing of the carbanilate).
38.2 A preferred method is available in Test Method D 5897.
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´1
Designation: D817 – 96 (Reapproved 2004)
Standard Test Methods of Testing
Cellulose Acetate Propionate and Cellulose Acetate
Butyrate
This standard is issued under the fixed designation D817; 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.
´ NOTE—Eq 31 was corrected editorially in November 2008.
1. Scope D1343 Test Method for Viscosity of Cellulose Derivatives
by Ball-Drop Method
1.1 These test methods cover procedures for the testing of
D2929 Test Method for Sulfur Content of Cellulosic Mate-
cellulose acetate propionates and acetate butyrates. These
rials by X-Ray Fluorescence
esters may vary widely in composition and properties, so
D5897 Test Method for Determination of Percent Hydroxyl
certain of the procedures can be used only in the ranges of
on Cellulose Esters by Potentiometric Titration—
composition where they are suitable.
Alternative Method
1.2 The values stated in SI units are to be regarded as the
2.2 ASTM Adjuncts:
standard. The values given in parentheses are for information
Color and Haze Apparatus
only.
1.3 The test procedures appear in the following sections:
3. Reagents
Sections
3.1 Purity of Reagents—Reagent grade chemicals shall be
Acetyl Propionyl or Butyryl Contents 28-37
Acetyl Content, Apparent 18-27
used in all tests. Unless otherwise indicated, it is intended that
Acidity, Free 12-17
all reagents shall conform to the specifications of the Commit-
Ash 7-10
tee onAnalytical Reagents of theAmerican Chemical Society,
Color and Haze 77-81
Heat Stability 57-65
where such specifications are available. Other grades may be
Hydroxyl Content 38-44
used, provided it is first ascertained that the reagent is of
Hydroxyl Content, Primary 46-50
sufficiently high purity to permit its use without lessening the
Intrinsic Viscosity 67-71
Moisture Content 5-6
accuracy of the determination.
Sulfur or Sulfate Content 51-56
Viscosity 74-75
4. Conditioning
Limiting Viscosity Number 67-71
4.1 Conditioning—Condition the test specimens at 23 6
1.4 This standard does not purport to address the safety
2°C(73.4 63.6°F)and50 65 %relativehumidityfornotless
concerns, if any, associated with its use. It is the responsibility
than 40 h prior to test in accordance with Procedure A of
of the user of this standard to establish appropriate safety and
Practice D618, for those tests where conditioning is required.
health practices and determine the applicability of regulatory
In cases of disagreement, the tolerances shall be 6 1°C
limitations prior to use.
(61.8°F) and 62 % relative humidity.
4.2 Test Conditions—Conduct tests in the Standard Labora-
2. Referenced Documents
tory Atmosphere of 23 6 2°C (73.4 6 3.6°F) and 50 65%
2.1 ASTM Standards:
relative humidity, unless otherwise specified in the test meth-
D618 Practice for Conditioning Plastics for Testing
ods. In cases of disagreements, the tolerances shall be 61°C
(61.8°F) and 6 2 % relative humidity.
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. Available from ASTM International Headquarters. Order Adjunct No.
Current edition approved June 1, 2004. Published June 2004. Originally ADJD0817.
approved in 1944. Last previous edition approved in 1996 as D817 – 96. DOI: Reagent Chemicals, American Chemical Society Specifications, American
10.1520/D0817-96R04E01. 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.
´1
D817 – 96 (2004)
MOISTURE CONTENT 12. Reagents
12.1 Acetone, neutral.
5. Procedure
12.2 Methyl Red Indicator Solution (0.4 g/L)—Dissolve 0.1
5.1 Transfer about5gofthe sample to a tared, low,
g of methyl red in 3.72 mL of 0.1000 N NaOH solution and
wide-form weighing bottle and weigh to the nearest 0.001 g.
dilute to 250 mL with water. Filter if necessary.
Dry in an oven for2hat105 6 3°C. Remove the bottle from
12.3 Phenolphthalein Indicator Solution (1 g/100 mL)—
the oven, cover, cool in a desiccator, and weigh.
Dissolve 1 g phenolphthalein in 100 mL of ethyl alco-
6. Calculation hol (95 %).
12.4 Sodium Hydroxide, Standard Solution (0.01 N)—
6.1 Calculate the percentage of moisture as follows:
Prepare and standardize a 0.01N solution of sodium hydroxide
Moisture, % 5 ~A/B! 3 100 (1)
(NaOH).
where:
A = weight loss on heating, g, and Test Method A—For Samples Containing Not More than
B = sample used, g. About 30% Propionyl or Butyryl
ASH
13. Procedure
7. Significance and Use 13.1 Shake5gofthesample,correctedformoisturecontent
if necessary, in a 250-mL Erlenmeyer flask with 150 mL of
7.1 Ash content gives an estimate of the inorganic content
freshly boiled, cold water. Stopper the flask and allow it to
of cellulose ester samples. The presence of high levels of
stand for 3 h. Filter off the cellulose ester and wash it with
inorganic content (ash) can be detrimental to the melt stability
water. Titrate the combined filtrate and washings with 0.01 N
and optical clarity of a cellulose ester in melt processing or act
NaOH solution, using phenolphthalein indicator solution.
as a potential source of insolubles when the ester is used in
13.2 Runablankdeterminationonthewater,usingthesame
solution.
volume as was used in extracting the sample.
8. Procedure
14. Calculation
8.1 Dry the sample for2hat105 6 3°C and weigh 10 to 50
g, to the nearest 0.01 to 0.1 g, depending on its ash content and
14.1 Calculate the percentage of acidity as free acetic acid
the accuracy desired. Burn directly over a flame in a 100-mL
as follows:
tared platinum crucible that has been heated to constant weight
Free acetic acid, % 5 $@~A 2B!C 3 0.06]/W% 3 100 (3)
and weighed to the nearest 0.1 mg.Add the sample in portions
if more than 10 g is taken. The sample should burn gently and
where:
the portions should be added as the flame subsides. Continue
A = NaOH solution used to titrate the sample, mL,
heating with a burner only as long as the residue burns with a
B = NaOH solution used to titrate the blank, mL,
flame. Transfer the crucible to a muffle furnace and heat at 550
C = normality of the NaOH solution, and
to 600°C for 3 h, or longer if required, to burn all the carbon. W = sample used, g.
Allowthecrucibletocoolandthentransferit,whilestillwarm,
to a desiccator. When the crucible has cooled to room tem-
Test Method B—For Samples Containing More than About
perature, weigh accurately to the nearest 0.1 mg.
7% Propionyl or Butyryl and Particularly Suitable for
Samples Containing More than 30% Propionyl or Butyryl
9. Calculation
9.1 Calculate the percentage of ash as follows:
15. Procedure
Ash, % 5 ~A/B! 3 100 (2)
15.1 Dissolve 10.0 g of the sample, corrected for moisture
content if necessary, in 200 mL of neutral acetone plus 20 mL
where:
of water. When completely dissolved, add 50 mL of water and
A = ash, g, and
shake well to precipitate the ester in a finely divided form.Add
B = sample used, g.
3 drops of methyl red indicator solution and titrate to a
10. Precision and Bias lemon-yellow end point and 0.01 N NaOH solution.
15.2 Make a blank determination on the reagents.
10.1 No statement on bias can be made as no reference
material is available as a standard.
16. Calculation
FREE ACIDITY
16.1 Calculate the free acid content as acetic acid as
directed in Section 14.
11. Significance and Use
11.1 Free acidity is a measure of unesterified organic acid in
17. Precision and Bias
the ester. The presence of high levels of free acid is potentially
detrimental to melt processing of the ester and can impact the 17.1 No statement on bias can be made as no reference
odor of the ester. material is available as a standard.
´1
D817 – 96 (2004)
APPARENTACETYL CONTENT 21.5 Sodium Hydroxide, Standard Solution (0.1 N)—
Prepare and standardize a 0.1 N solution of NaOH.
18. Scope 21.6 Sulfuric Acid Standard (1.0 N)—Prepare and stan-
dardize a 1.0 N solution of sulfuric acid (H SO ).
18.1 The test methods described in the following 20 to 26 2 4
21.7 Phenolphthalein Indicator Solution (1 g/100 mL)—
cover the determination of the saponification value of the
Dissolve1gof phenolphthalein in 100 mL of ethyl alcohol
sample calculated as percentage of apparent acetyl, equivalent
(95 %).
weight 43. This value is required in the calculation of acetyl
and propionyl or butyryl contents in 36.1.
22. Procedure
18.2 The test method used should be specified or agreed
22.1 Dry the ground well-mixed sample in weighing bottle
upon. The choice depends on the propionyl or butyryl content
for2hat105 6 3°C and weigh 1.9 6 0.05 g of the dried
and the physical condition of the sample. Ordinarily, Test
sample by difference to the nearest 1 mg into a 500-mL
MethodAis recommended for samples having less than about
Erlenmeyer flask. Prepare a blank by drying approximately 3.8
35 % propionyl or butyryl and Test Method B for samples
gofpotassiumacidphthalateandweighingitbydifferenceinto
having more than that amount.
a flask as described above. Carry the blank through the entire
procedure.
19. Significance and Use
NOTE 1—Potassium acid phthalate is used so that the concentration of
19.1 Apparent acetyl content is a measure of the saponifi-
the NaOH in contact with the solvent in the blank will be approximately
cation value of the ester. Apparent acetyl value is required in
the same as that in contact with the sample and so that the titration of the
the calculation of acetyl, propionyl, and butyryl content in
blank will be approximately the same as the titration of the sample, thus
36.1.
avoiding errors caused by using a different buret for the titration of the
blank and the sample or by refilling the 15-mLburet. If desired, however,
Test Method A—For Samples Containing Less than About
the potassium acid phthalate may be omitted.
35% Propionyl or Butyryl
22.2 For acetone-soluble sample, put the sample into solu-
tion as follows: Add 150 mL of acetone and 5 to 10 mL of
20. Apparatus
water and swirl to mix. Stopper the flask and allow it to stand
20.1 Weighing Bottle, glass-stoppered, 15-mL capacity,
with occasional swirling until solution is complete. Solution
25-mm diameter by 50 mm high.
may be hastened by magnetic stirring or by any suitable
20.2 Tray, copper or aluminum, approximately 137 mm
mechanical shaking that will provide a gentle rocking type of
square, containing 25 compartments 25 mm square. Each
agitation to avoid splashing the solution on the stopper. It is
compartment shall have the correct dimensions to contain one
essential that complete solution be effected.
weighing bottle.The entire tray shall fit inside a desiccator and
22.3 For acetone-insoluble samples of low propionyl or
should have a basket-type handle to facilitate the introduction
butyryl content, dissolve the sample by either of the following
and removal of the tray (convenient but not essential).
two methods:
20.3 Buret, automatic zero, 35-mL, 25-mL bulb, stem
22.3.1 Gently rotate the flask by hand to distribute and
graduated from 25 to 35 mL in 0.05-mL increments; or pipet,
spread the sample in a thin layer over the bottom of the flask.
automatic zero, 30-mL for NaOH solution (40 g/L).
Add 70 mL of acetone to the flask and swirl gently until the
20.4 Buret, automatic zero, 15-mL, 10-mL bulb, stem
sample particles are completely wetted and evenly dispersed.
graduated from 10 to 15 mL in 0.05-mL increments, for 1 N
Stopper the flask and allow it to stand undisturbed for 10 min.
H SO .
2 4 Carefully add 30 mL of dimethyl sulfoxide from a graduate to
20.5 Buret, 5-mL, in 0.01 or 0.1-mL divisions, for back
the flask, pouring the solvent down the sides of the flask to
titration with 0.1 N NaOH solution.
wash down any sample particles clinging to the side. Stopper
20.6 Magnetic Stirrer, for single flask.
the flask and allow it to stand with occasional swirling until
20.7 Magnetic Stirrer, capacity twelve or more flasks.
solution is complete. Magnetic stirring or gentle mechanical
20.8 Stirring Bars, stainless steel Type 416, length 50 mm,
agitation that will not splash the solution is recommended.
diameter 5 to 6 mm or equivalent, dimensions not critical.
When solution appears to be complete, add 50 mL of acetone
and swirl or stir for 5 min. Proceed in accordance with 22.4.
21. Reagents
22.3.2 Dimethyl sulfoxide is the preferred solvent, but if it
21.1 Acetone—Add one 30-mL portion of 1.0 N NaOH is not available, spread the sample in a thin layer over the
solution to a mixture of 150 mLacetone and 100 mLhot water, bottom of the flask, add 15 mL of acetone, swirl to wet the
allow to stand with frequent swirling for 30 min, and titrate particles with acetone, stopper the flask, and allow the mixture
with 1.0 N H SO .Add another 30-mLportion of 1.0 N NaOH to stand undisturbed for 20 min. Add 75 mL of pyridine
2 4
solution to 100 mLof hot water, allow to stand for 30 min, and without shaking or swirling and allow the mixture to stand for
titrate as above. The difference between the two titrations shall 10 min. Heat the solution just to boiling and swirl or stir for 5
not exceed 0.05 mL. min. Again heat to boiling and swirl or stir for 10 min.
21.2 Dimethyl Sulfoxide. Continue to heat and stir until the mixture is homogeneous and
21.3 Pyridine. all large gel masses are broken down into individual highly
21.4 SodiumHydroxideSolution(40g/L)—Dissolve 40 g of swollen particles. When these highly swollen gel particles are
sodium hydroxide (NaOH) in water and dilute to 1 L. well dispersed and are not fused together in large gel masses,
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D817 – 96 (2004)
in the blank is recommended. When it is not used, the term P drops out of
no further heating is necessary. Cool the flask, add 30 mL of
the equation.
acetone, and swirl or stir for 5 min.
22.4 Add 30 mL of NaOH solution (40 g/L) with constant
Test Method B—For Cellulose Esters Co
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
Designation:D 817–96(Reapproved2004) Designation: D817 – 96 (Reapproved 2004)
Standard Test Methods of Testing
Cellulose Acetate Propionate and Cellulose Acetate
Butyrate
This standard is issued under the fixed designation D817; 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.
´ NOTE—Eq 31 was corrected editorially in November 2008.
1. Scope
1.1 These test methods cover procedures for the testing of cellulose acetate propionates and acetate butyrates. These esters may
vary widely in composition and properties, so certain of the procedures can be used only in the ranges of composition where they
are suitable.
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 The test procedures appear in the following sections:
Sections
Acetyl Propionyl or Butyryl Contents 28-37
Acetyl Content, Apparent 18-27
Acidity, Free 12-17
Ash 7-10
Color and Haze 77-81
Heat Stability 57-65
Hydroxyl Content 38-44
Hydroxyl Content, Primary 46-50
Intrinsic Viscosity 67-71
Moisture Content 5-6
Sulfur or Sulfate Content 51-56
Viscosity 74-75
Limiting Viscosity Number 67-71
1.4 This standard does not purport to address 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.
2. Referenced Documents
2.1 ASTM Standards:
D618 Practice for Conditioning Plastics for Testing
D1343 Test Method for Viscosity of Cellulose Derivatives by Ball-Drop Method
D2929 Test Method for Sulfur Content of Cellulosic Materials by X-Ray Fluorescence
D5897 Test Method for Determination of Percent Hydroxyl on Cellulose Esters by Potentiometric TitrationAlternative Method
2.2 ASTM Adjuncts:
Color and Haze Apparatus
3. Reagents
3.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, 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 1944. Last previous edition approved in 1996 as D817 – 96. DOI:
10.1520/D0817-96R04E01.
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. ForAnnualBookofASTMStandards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from ASTM International Headquarters. Order Adjunct No. ADJD0817.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
´1
D817 – 96 (2004)
such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
4. Conditioning
4.1 Conditioning—Condition the test specimens at 23 6 2°C (73.4 6 3.6°F) and 50 6 5 % relative humidity for not less than
40 h prior to test in accordance with ProcedureAof Practice D 618D618, for those tests where conditioning is required. In cases
of disagreement, the tolerances shall be 6 1°C (61.8°F) and 62 % relative humidity.
4.2 Test Conditions—Conduct tests in the Standard LaboratoryAtmosphere of 23 6 2°C (73.4 6 3.6°F) and 50 6 5 % relative
humidity, unless otherwise specified in the test methods. In cases of disagreements, the tolerances shall be 61°C (61.8°F) and 6
2 % relative humidity.
MOISTURE CONTENT
5. Procedure
5.1 Transfer about5gofthe sample to a tared, low, wide-form weighing bottle and weigh to the nearest 0.001 g. Dry in an oven
for2hat105 6 3°C. Remove the bottle from the oven, cover, cool in a desiccator, and weigh.
6. Calculation
6.1 Calculate the percentage of moisture as follows:
(1) Moisture, % 5 ~A/B! 3 100
where:
A = weight loss on heating, g, and
B = sample used, g.
ASH
7. Significance and Use
7.1 Ash content gives an estimate of the inorganic content of cellulose ester samples. The presence of high levels of inorganic
content (ash) can be detrimental to the melt stability and optical clarity of a cellulose ester in melt processing or act as a potential
source of insolubles when the ester is used in solution.
8. Procedure
8.1 Dry the sample for2hat105 6 3°C and weigh 10 to 50 g, to the nearest 0.01 to 0.1 g, depending on its ash content and
the accuracy desired. Burn directly over a flame in a 100-mL tared platinum crucible that has been heated to constant weight and
weighed to the nearest 0.1 mg. Add the sample in portions if more than 10 g is taken. The sample should burn gently and the
portions should be added as the flame subsides. Continue heating with a burner only as long as 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, to burn all the carbon.Allow the
crucible to cool and then transfer it, while still warm, to a desiccator. When the crucible has cooled to room temperature, weigh
accurately to the nearest 0.1 mg.
9. Calculation
9.1 Calculate the percentage of ash as follows:
where:
A = ash, g, and
B = sample used, g.
10. Precision and Bias
10.1 No statement on bias can be made as no reference material is available as a standard.
FREE ACIDITY
11. Significance and Use
11.1 Free acidity is a measure of unesterified organic acid in the ester. The presence of high levels of free acid is potentially
detrimental to melt processing of the ester and can impact the odor of the ester.
Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by
the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National
Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
´1
D817 – 96 (2004)
12. Reagents
12.1 Acetone, neutral.
12.2 Methyl Red Indicator Solution (0.4 g/L)—Dissolve 0.1 g of methyl red in 3.72 mL of 0.1000 N NaOH solution and dilute
to 250 mL with water. Filter if necessary.
12.3 Phenolphthalein Indicator Solution (1 g/100 mL)—Dissolve 1 g phenolphthalein in 100 mL of ethyl alcohol
(95 %).
12.4 SodiumHydroxide,StandardSolution (0.01N)—Prepare and standardize a 0.01N solution of sodium hydroxide (NaOH).
Test Method A—For Samples Containing Not More than About 30% Propionyl or Butyryl
13. Procedure
13.1 Shake5gofthe sample, corrected for moisture content if necessary, in a 250-mLErlenmeyer flask with 150 mLof freshly
boiled, cold water. Stopper the flask and allow it to stand for 3 h. Filter off the cellulose ester and wash it with water. Titrate the
combined filtrate and washings with 0.01 N NaOH solution, using phenolphthalein indicator solution.
13.2 Run a blank determination on the water, using the same volume as was used in extracting the sample.
14. Calculation
14.1 Calculate the percentage of acidity as free acetic acid as follows:
where:
A = NaOH solution used to titrate the sample, mL,
B = NaOH solution used to titrate the blank, mL,
C = normality of the NaOH solution, and
W = sample used, g.
Test Method B—For Samples Containing More than About 7% Propionyl or Butyryl and Particularly Suitable for Samples
Containing More than 30% Propionyl or Butyryl
15. Procedure
15.1 Dissolve 10.0 g of the sample, corrected for moisture content if necessary, in 200 mL of neutral acetone plus 20 mL of
water.When completely dissolved, add 50 mLof water and shake well to precipitate the ester in a finely divided form.Add 3 drops
of methyl red indicator solution and titrate to a lemon-yellow end point and 0.01 N NaOH solution.
15.2 Make a blank determination on the reagents.
16. Calculation
16.1 Calculate the free acid content as acetic acid as directed in Section 14.
17. Precision and Bias
17.1 No statement on bias can be made as no reference material is available as a standard.
APPARENTACETYL CONTENT
18. Scope
18.1 The test methods described in the following 20 to 26 cover the determination of the saponification value of the sample
calculated as percentage of apparent acetyl, equivalent weight 43. This value is required in the calculation of acetyl and propionyl
or butyryl contents in 36.1.
18.2 The test method used should be specified or agreed upon. The choice depends on the propionyl or butyryl content and the
physical condition of the sample. Ordinarily, Test Method A is recommended for samples having less than about 35 % propionyl
or butyryl and Test Method B for samples having more than that amount.
19. Significance and Use
19.1 Apparent acetyl content is a measure of the saponification value of the ester. Apparent acetyl value is required in the
calculation of acetyl, propionyl, and butyryl content in 36.1.
Test Method A—For Samples Containing Less than About 35% Propionyl or Butyryl
20. Apparatus
20.1 Weighing Bottle, glass-stoppered, 15-mL capacity, 25-mm diameter by 50 mm high.
20.2 Tray, copper or aluminum, approximately 137 mm square, containing 25 compartments 25 mm square. Each compartment
shall have the correct dimensions to contain one weighing bottle. The entire tray shall fit inside a desiccator and should have a
basket-type handle to facilitate the introduction and removal of the tray (convenient but not essential).
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D817 – 96 (2004)
20.3 Buret, automatic zero, 35-mL, 25-mL bulb, stem graduated from 25 to 35 mL in 0.05-mL increments; or pipet, automatic
zero, 30-mL for NaOH solution (40 g/L).
20.4 Buret, automatic zero, 15-mL, 10-mL bulb, stem graduated from 10 to 15 mL in 0.05-mL increments, for 1 N H SO .
2 4
20.5 Buret, 5-mL, in 0.01 or 0.1-mL divisions, for back titration with 0.1 N NaOH solution.
20.6 Magnetic Stirrer, for single flask.
20.7 Magnetic Stirrer, capacity twelve or more flasks.
20.8 Stirring Bars, stainless steel Type 416, length 50 mm, diameter 5 to 6 mm or equivalent, dimensions not critical.
21. Reagents
21.1 Acetone—Add one 30-mL portion of 1.0 N NaOH solution to a mixture of 150 mL acetone and 100 mL hot water, allow
to stand with frequent swirling for 30 min, and titrate with 1.0 N H SO . Add another 30-mL portion of 1.0 N NaOH solution to
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100 mL of hot water, allow to stand for 30 min, and titrate as above. The difference between the two titrations shall not exceed
0.05 mL.
21.2 Dimethyl Sulfoxide.
21.3 Pyridine.
21.4 Sodium Hydroxide Solution (40 g/L)—Dissolve 40 g of sodium hydroxide (NaOH) in water and dilute to 1 L.
21.5 Sodium Hydroxide, Standard Solution (0.1 N)—Prepare and standardize a 0.1 N solution of NaOH.
21.6 Sulfuric Acid Standard (1.0 N)—Prepare and standardize a 1.0 N solution of sulfuric acid (H SO ).
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21.7 Phenolphthalein Indicator Solution (1 g/100 mL)—Dissolve1gof phenolphthalein in 100 mL of ethyl alcohol (95 %).
22. Procedure
22.1 Dry the ground well-mixed sample in weighing bottle for2hat105 6 3°C and weigh 1.9 6 0.05 g of the dried sample
by difference to the nearest 1 mg into a 500-mL Erlenmeyer flask. Prepare a blank by drying approximately 3.8 g of potassium
acid phthalate and weighing it by difference into a flask as described above. Carry the blank through the entire procedure.
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 the
same as that in contact with the sample and so that the titration of the blank will be approximately the same as the titration of the sample, thus avoiding
errors caused by using a different buret for the titration of the blank and the sample or by refilling the 15-mL buret. If desired, however, the potassium
acid phthalate may be omitted.
22.2 For acetone-soluble sample, put the sample into solution as follows:Add 150 mL of acetone and 5 to 10 mL of water and
swirl to mix. Stopper the flask and allow it to stand with occasional swirling until solution is complete. Solution may be hastened
by magnetic stirring or by any suitable mechanical shaking that will provide a gentle rocking type of agitation to avoid splashing
the solution on the stopper. It is essential that complete solution be effected.
22.3 For acetone-insoluble samples of low propionyl or butyryl content, dissolve the sample by either of the following two
methods:
22.3.1 Gently rotate the flask by hand to distribute and spread the sample in a thin layer over the bottom of the flask. Add 70
mLof acetone to the flask and swirl gently until the sample particles are completely wetted and evenly dispersed. Stopper the flask
and allow it to stand undisturbed for 10 min. Carefully add 30 mL of dimethyl sulfoxide from a graduate to the flask, pouring the
solvent down the sides of the flask to wash down any sample particles clinging to the side. Stopper the flask and allow it to stand
withoccasionalswirlinguntilsolutioniscomplete.Magneticstirringorgentlemechanicalagitationthatwillnotsplashthesolution
is recommended. When solution appears to be complete, add 50 mL of acetone and swirl or stir for 5 min. Proceed in accordance
with 22.4.
22.3.2 Dimethyl sulfoxide is the preferred solvent, but if it is not available, spread the sample in a thin layer over the bottom
of the flask, add 15 mL of acetone, swirl to wet the particles with acetone, stopper the flask, and allow the mixture to stand
undisturbed for 20 min. Add 75 mL of pyridine without shaking or swirling and allow the mixture to stand for 10 min. Heat the
solution just to boiling and swirl or stir for 5 min.Again heat to boiling and swirl or stir for 10 min. Continue to heat and stir until
the mixture is homogeneous and all large gel masses are broken down into individual highly swollen particles. When these highly
swollen gel particles are well dispersed and are not fused together in large gel masses, no further heating is necessary. Cool t
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