ASTM D817-12(2019)

Standard Test Methods of Testing Cellulose Acetate Propionate and Cellulose Acetate Butyrate

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.
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 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Nov-2019
• ICS: 85.040 - Pulps
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.36 - Cellulose and Cellulose Derivatives

Relations

• Replaces: ASTM D817-12 - Standard Test Methods of Testing Cellulose Acetate Propionate and Cellulose Acetate Butyrate
• Effective Date: 01-Dec-2019
• Refers: ASTM D2929-89(2019)e1 - Standard Test Method for Sulfur Content of Cellulosic Materials by X-Ray Fluorescence
• Effective Date: 01-Oct-2019
• Refers: ASTM D2929-89(2011) - Standard Test Method for Sulfur Content of Cellulosic Materials by X-Ray Fluorescence
• Effective Date: 01-Jun-2011
• Refers: ASTM D1343-95(2011) - Standard Test Method for Viscosity of Cellulose Derivatives by Ball-Drop Method
• Effective Date: 01-Jun-2011
• Refers: ASTM D618-08 - Standard Practice for Conditioning Plastics for Testing
• Effective Date: 01-Nov-2008
• Refers: ASTM D5897-96(2007) - Standard Test Method for Determination of Percent Hydroxyl on Cellulose Esters by Potentiometric Titration-Alternative Method
• Effective Date: 01-Jun-2007
• Refers: ASTM D2929-89(2006) - Standard Test Method for Sulfur Content of Cellulosic Materials by X-Ray Fluorescence
• Effective Date: 01-Apr-2006
• Refers: ASTM D1343-95(2006) - Standard Test Method for Viscosity of Cellulose Derivatives by Ball-Drop Method
• Effective Date: 01-Apr-2006
• Refers: ASTM D618-05 - Standard Practice for Conditioning Plastics for Testing
• Effective Date: 01-Nov-2005
• Refers: ASTM D618-00 - Standard Practice for Conditioning Plastics for Testing
• Effective Date: 10-Nov-2000
• Refers: ASTM D2929-89(2000) - Standard Test Method for Sulfur Content of Cellulosic Materials by X-ray Fluorescence
• Effective Date: 10-Mar-2000
• Refers: ASTM D1343-95(2000) - Standard Test Method for Viscosity of Cellulose Derivatives by Ball-Drop Method
• Effective Date: 10-Mar-2000
• Refers: 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
• Refers: ASTM D5897-96 - Standard Test Method for Determination of Percent Hydroxyl on Cellulose Esters by Potentiometric Titration-Alternative Method
• Effective Date: 10-Jan-1996
• Referred By: ASTM E1899-23 - Standard Test Method for Hydroxyl Groups Using Reaction with <emph type="ital">p</emph >-Toluenesulfonyl Isocyanate (TSI) and Potentiometric Titration with Tetrabutylammonium Hydroxide
• Effective Date: 01-Dec-2019

Overview

ASTM D817-12(2019), published by ASTM International, is the standard titled Standard Test Methods of Testing Cellulose Acetate Propionate and Cellulose Acetate Butyrate. This specification establishes uniform procedures for evaluating key chemical and physical properties of cellulose acetate-based esters, specifically cellulose acetate propionates and cellulose acetate butyrates. These polymers are widely used in the plastics and coatings industries due to their versatile performance characteristics.

The standard covers a range of test methods designed to accommodate the wide variety of compositions and properties that cellulose ester products can exhibit. It offers procedures for testing properties such as ash content, acetyl and butyryl/propionyl content, moisture, intrinsic viscosity, hydroxyl content, color, haze, heat stability, acidity, sulfur content, and more.

Key Topics

ASTM D817-12(2019) encompasses several important test categories for cellulose acetate propionates and butyrates:

• Ash Content: Estimates inorganic content present in samples. High ash can negatively impact melt stability and optical clarity in processing applications.
• Moisture and Acidity: Determines water content and free acids, which affect processability and final properties.
• Acetyl, Propionyl, and Butyryl Contents: Measures the level of esterification, directly impacting polymer characteristics like solubility, flexibility, and clarity.
• Intrinsic and Limiting Viscosity: Used to assess polymer molecular weight and processability.
• Color and Haze: Evaluates the optical appearance for applications demanding high clarity.
• Heat Stability: Essential for ascertaining performance under processing conditions.
• Hydroxyl and Sulfur Content: Important for quality, performance, and regulatory compliance.

Values are reported in SI units to maintain consistency globally.

Applications

Practical applications of the ASTM D817 test methods span across multiple industries and processes:

• Plastics Manufacturing: Ensures quality of cellulose acetate propionate and butyrate resins used in injection molding, extrusion, and film production.
• Coatings and Laminates: Provides data essential for manufacturers of coatings or films requiring precise control over optical and mechanical properties.
• Product Development and Quality Control: Enables laboratories and manufacturers to compare batches, qualify raw materials, and troubleshoot failures.
• Regulatory Compliance: Ash, sulfur, and residual acidity testing help ensure finished products meet regulatory and safety standards.
• Research and Development: Facilitates composition-property studies for new cellulose ester formulations.

These test methods help maintain product uniformity, support process optimization, and safeguard end-use performance.

Related Standards

For organizations and laboratories working with cellulose esters, the following related ASTM standards and practices may also be relevant:

• ASTM D618: Practice for Conditioning Plastics for Testing
• ASTM D1343: Test Method for Viscosity of Cellulose Derivatives by Ball-Drop Method
• ASTM D2929: Test Method for Sulfur Content of Cellulosic Materials by X-Ray Fluorescence
• ASTM D5897: Test Method for Determination of Percent Hydroxyl on Cellulose Esters by Potentiometric Titration

ASTM D817-12(2019) aligns with internationally recognized standardization principles, as established by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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Keywords: ASTM D817, cellulose acetate propionate, cellulose acetate butyrate, polymer test methods, ash content, acetyl content, moisture, viscosity, hydroxyl, coatings, plastics testing, cellulose esters, international standards, quality control.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D817 − 12 (Reapproved 2019)
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.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 These test methods cover procedures for the testing of 2.1 ASTM Standards:
cellulose acetate propionates and acetate butyrates. These D618Practice for Conditioning Plastics for Testing
esters may vary widely in composition and properties, so D1343Test Method for Viscosity of Cellulose Derivatives
certain of the procedures can be used only in the ranges of by Ball-Drop Method
composition where they are suitable. D2929Test Method for Sulfur Content of Cellulosic Mate-
rials by X-Ray Fluorescence
1.2 The values stated in SI units are to be regarded as the
D5897Test Method for Determination of Percent Hydroxyl
standard. The values given in parentheses are for information
on Cellulose Esters by Potentiometric Titration—
only.
Alternative Method
1.3 The test procedures appear in the following sections:
3. Reagents
Sections
Acetyl Propionyl or Butyryl Contents 28–37
3.1 Purity of Reagents—Reagent grade chemicals shall be
Acetyl Content, Apparent 18–27
Acidity, Free 12–17 used in all tests. Unless otherwise indicated, it is intended that
Ash 7–10
all reagents shall conform to the specifications of the Commit-
Color and Haze 77–81
tee onAnalytical Reagents of theAmerican Chemical Society,
Heat Stability 57–65
where such specifications are available. Other grades may be
Hydroxyl Content 38–44
Hydroxyl Content, Primary 46–50
used, provided it is first ascertained that the reagent is of
Intrinsic Viscosity 67–71
sufficiently high purity to permit its use without lessening the
Moisture Content 5-6
accuracy of the determination.
Sulfur or Sulfate Content 51–56
Viscosity 74-75
Limiting Viscosity Number 67–71
4. Conditioning
1.4 This standard does not purport to address all of the
4.1 Conditioning—Condition the test specimens at 23 6
safety concerns, if any, associated with its use. It is the
2°C(73.4 63.6°F)and50 65%relativehumidityfornotless
responsibility of the user of this standard to establish appro-
than 40 h prior to test in accordance with Procedure A of
priate safety, health, and environmental practices and deter-
Practice D618, for those tests where conditioning is required.
mine the applicability of regulatory limitations prior to use.
In cases of disagreement, the tolerances shall be 61°C
1.5 This international standard was developed in accor-
(61.8°F) and 62% relative humidity.
dance with internationally recognized principles on standard-
4.2 Test Conditions—Conduct tests in the Standard Labora-
ization established in the Decision on Principles for the
tory Atmosphere of 23 6 2°C (73.4 6 3.6°F) and 50 65%
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
1 3
These test methods are under the jurisdiction of ASTM Committee D01 on ACS Reagent Chemicals, Specifications and Procedures for Reagents and
Paint and Related Coatings, Materials, and Applications and are the direct Standard-Grade Reference Materials, American Chemical Society, Washington,
responsibility of Subcommittee D01.36 on Cellulose and Cellulose Derivatives. DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
Current edition approved Dec. 1, 2019. Published December 2019. Originally Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
approved in 1944. Last previous edition approved in 2012 as D817–12. DOI: U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
10.1520/D0817-12R19. copeial Convention, Inc. (USPC), Rockville, MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D817 − 12 (2019)
relative humidity, unless otherwise specified in the test meth- FREE ACIDITY
ods. In cases of disagreements, the tolerances shall be 61°C
(61.8°F) and 62% relative humidity.
11. Significance and Use
11.1 Freeacidityisameasureofunesterifiedorganicacidin
MOISTURE CONTENT
the ester.The presence of high levels of free acid is potentially
detrimental to melt processing of the ester and can impact the
5. Procedure
odor of the ester.
5.1 Transfer about5gofthe sample to a tared, low,
wide-form weighing bottle and weigh to the nearest 0.001 g.
12. Reagents
Dry in an oven for2hat105 6 3°C. Remove the bottle from
12.1 Acetone, neutral.
the oven, cover, cool in a desiccator, and weigh.
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
6. Calculation
dilute to 250 mL with water. Filter if necessary.
6.1 Calculate the percentage of moisture as follows:
12.3 Phenolphthalein Indicator Solution (1 g/100 mL)—
Moisture, % 5 A/B 3100 (1)
~ !
Dissolve 1gphenolphthalein in 100 mL of ethyl alco-
hol (95%).
where:
12.4 Sodium Hydroxide, Standard Solution (0.01 N)—
A = weight loss on heating, g, and
Prepareandstandardizea0.01 Nsolutionofsodiumhydroxide
B = sample used, g.
(NaOH).
ASH
Test Method A—For Samples Containing Not More than
About 30 % Propionyl or Butyryl
7. Significance and Use
7.1 Ash content gives an estimate of the inorganic content
13. Procedure
of cellulose ester samples. The presence of high levels of
13.1 Shake5gofthesample,correctedformoisturecontent
inorganic content (ash) can be detrimental to the melt stability
if necessary, in a 250-mL Erlenmeyer flask with 150 mL of
and optical clarity of a cellulose ester in melt processing or act
freshly boiled, cold water. Stopper the flask and allow it to
as a potential source of insolubles when the ester is used in
stand for 3 h. Filter off the cellulose ester and wash it with
solution.
water. Titrate the combined filtrate and washings with 0.01 N
NaOH solution, using phenolphthalein indicator solution.
8. Procedure
13.2 Runablankdeterminationonthewater,usingthesame
8.1 Drythesamplefor2hat105 63°Candweigh10to50
volume as was used in extracting the sample.
g,tothenearest0.01to0.1g,dependingonitsashcontentand
the accuracy desired. Burn directly over a flame in a 100-mL
14. Calculation
taredplatinumcruciblethathasbeenheatedtoconstantweight
14.1 Calculate the percentage of acidity as free acetic acid
and weighed to the nearest 0.1 mg.Add the sample in portions
as follows:
if more than 10 g is taken. The sample should burn gently and
the portions should be added as the flame subsides. Continue
Freeaceticacid, % 5 A 2 B C 30.06 /W 3100 (3)
$@~ ! # %
heating with a burner only as long as the residue burns with a
where:
flame.Transfer the crucible to a muffle furnace and heat at 550
A = NaOH solution used to titrate the sample, mL,
to 600°C for 3 h, or longer if required, to burn all the carbon.
B = NaOH solution used to titrate the blank, mL,
Allowthecrucibletocoolandthentransferit,whilestillwarm,
C = normality of the NaOH solution, and
to a desiccator. When the crucible has cooled to room
W = sample used, g.
temperature, weigh accurately to the nearest 0.1 mg.
Test Method B—For Samples Containing More than About
9. Calculation
7 %Propionyl or Butyryl and Particularly Suitable for
Samples Containing More than 30 % Propionyl or Butyryl
9.1 Calculate the percentage of ash as follows:
Ash, % 5 A/B 3100 (2)
~ !
15. Procedure
where:
15.1 Dissolve 10.0 g of the sample, corrected for moisture
A = ash, g, and
content if necessary, in 200 mL of neutral acetone plus 20 mL
B = sample used, g.
of water. When completely dissolved, add 50 mLof water and
shakewelltoprecipitatetheesterinafinelydividedform.Add
10. Precision and Bias
3 drops of methyl red indicator solution and titrate to a
lemon-yellow end point and 0.01 N NaOH solution.
10.1 No statement on bias can be made as no reference
material is available as a standard. 15.2 Make a blank determination on the reagents.
D817 − 12 (2019)
16. Calculation 20.7 Magnetic Stirrer, capacity twelve or more flasks.
16.1 Calculate the free acid content as acetic acid as 20.8 Stirring Bars, stainless steel Type 416, length 50 mm,
directed in Section 14. diameter 5 to 6 mm or equivalent, dimensions not critical.
17. Precision and Bias
21. Reagents
17.1 No statement on bias can be made as no reference 21.1 Acetone—Add one 30-mL portion of 1.0 N NaOH
material is available as a standard. solutiontoamixtureof150mLacetoneand100mLhotwater,
allow to stand with frequent swirling for 30 min, and titrate
APPARENT ACETYL CONTENT
with 1.0 N H SO .Add another 30-mLportion of 1.0 N NaOH
2 4
solutionto100mLofhotwater,allowtostandfor30min,and
18. Scope
titrate as above.The difference between the two titrations shall
18.1 The test methods described in the following Sections
not exceed 0.05 mL.
20 to 26 cover the determination of the saponification value of
21.2 Dimethyl Sulfoxide.
thesamplecalculatedaspercentageofapparentacetyl,equiva-
21.3 Pyridine.
lent weight 43. This value is required in the calculation of
acetyl and propionyl or butyryl contents in 36.1.
21.4 Sodium Hydroxide Solution (40 g/L)—Dissolve40gof
sodium hydroxide (NaOH) in water and dilute to 1 L.
18.2 The test method used should be specified or agreed
upon. The choice depends on the propionyl or butyryl content
21.5 Sodium Hydroxide, Standard Solution (0.1 N)—
and the physical condition of the sample. Ordinarily, Test
Prepare and standardize a 0.1 N solution of NaOH.
MethodAis recommended for samples having less than about
21.6 Sulfuric Acid Standard (1.0 N)—Prepare and standard-
35% propionyl or butyryl and Test Method B for samples
ize a 1.0 N solution of sulfuric acid (H SO ).
2 4
having more than that amount.
21.7 Phenolphthalein Indicator Solution (1 g/100 mL)—
18.3 This international standard was developed in accor-
Dissolve1gof phenolphthalein in 100 mL of ethyl alcohol
dance with internationally recognized principles on standard-
(95%).
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
22. Procedure
mendations issued by the World Trade Organization Technical
22.1 Dry the ground well-mixed sample in weighing bottle
Barriers to Trade (TBT) Committee.
for2hat105 6 3°C and weigh 1.9 6 0.05 g of the dried
19. Significance and Use sample by difference to the nearest 1 mg into a 500-mL
Erlenmeyerflask.Prepareablankbydryingapproximately3.8
19.1 Apparent acetyl content is a measure of the saponifi-
gofpotassiumacidphthalateandweighingitbydifferenceinto
cation value of the ester. Apparent acetyl value is required in
a flask as described above. Carry the blank through the entire
the calculation of acetyl, propionyl, and butyryl content in
procedure.
36.1.
NOTE 1—Potassium acid phthalate is used so that the concentration of
Test Method A—For Samples Containing Less than About
the NaOH in contact with the solvent in the blank will be approximately
35 % Propionyl or Butyryl 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
20. Apparatus
blank and the sample or by refilling the 15-mLburet. If desired, however,
20.1 Weighing Bottle, glass-stoppered, 15-mL capacity,
the potassium acid phthalate may be omitted.
25-mm diameter by 50 mm high.
22.2 For acetone-soluble sample, put the sample into solu-
20.2 Tray, copper or aluminum, approximately 137 mm
tion as follows: Add 150 mL of acetone and 5 to 10 mL of
square, containing 25 compartments 25 mm square. Each water and swirl to mix. Stopper the flask and allow it to stand
compartment shall have the correct dimensions to contain one
with occasional swirling until solution is complete. Solution
weighingbottle.Theentiretrayshallfitinsideadesiccatorand may be hastened by magnetic stirring or by any suitable
should have a basket-type handle to facilitate the introduction
mechanical shaking that will provide a gentle rocking type of
and removal of the tray (convenient but not essential). agitation to avoid splashing the solution on the stopper. It is
essential that complete solution be effected.
20.3 Buret, automatic zero, 35-mL, 25-mL bulb, stem
graduated from 25 to 35 mL in 0.05-mL increments; or pipet, 22.3 For acetone-insoluble samples of low propionyl or
automatic zero, 30-mL for NaOH solution (40 g/L).
butyryl content, dissolve the sample by either of the following
two methods:
20.4 Buret, automatic zero, 15-mL, 10-mL bulb, stem
22.3.1 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 .
2 4
Add 70 mL of acetone to the flask and swirl gently until the
20.5 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.
20.6 Magnetic Stirrer, for single flask. Carefully add 30 mLof dimethyl sulfoxide from a graduate to
D817 − 12 (2019)
the flask, pouring the solvent down the sides of the flask to Acetyl, % 5 D 2 C N 2 B 2 A N 1P 30.04305 /W 3100
$@~ ! ~ ! # %
a b
wash down any sample particles clinging to the side. Stopper
(4)
the flask and allow it to stand with occasional swirling until
P 5 ~GH 31000!/204.2
solution is complete. Magnetic stirring or gentle mechanical
agitation that will not splash the solution is recommended.
where:
When solution appears to be complete, add 50 mL of acetone
A = NaOHsolutionrequiredfortitrationofthesample,mL,
and swirl or stir for 5 min. Proceed in accordance with 22.4.
B = NaOH solution required for titration of the blank, mL,
22.3.2 Dimethyl sulfoxide is the preferred solvent, but if it
N = normality of the NaOH solution,
b
is not available, spread the sample in a thin layer over the
C =H SO required for titration of the sample, mL
2 4
bottom of the flask, add 15 mL of acetone, swirl to wet the
D =H SO required for titration of the blank, mL,
2 4
particles with acetone, stopper the flask, and allow the mixture
N = normality of the H SO ,
a 2 4
to stand undisturbed for 20 min. Add 75 mL of pyridine P = milliequivalents of potassium acid phthalate,
G = potassium acid phthalate used, g,
without shaking or swirling and allow the mixture to stand for
H = purity factor for potassium acid phthalate, and
10 min. Heat the solution just to boiling and swirl or stir for 5
W = sample used, g.
min. Again heat to boiling and swirl or stir for 10 min.
NOTE 4—When equal volumes of alkali or acid are added to samples
Continuetoheatandstiruntilthemixtureishomogeneousand
andblank,theseamountscancelout.Thusonlytheamountsofeachadded
all large gel masses are broken down into individual highly
in the titration enter into the calculations. Use of potassium acid phthalate
swollen particles. When these highly swollen gel particles are
in the blank is recommended.When it is not used, the term P drops out of
well dispersed and are not fused together in large gel masses, the equation.
no further heating is necessary. Cool the flask, add 30 mL of
Test Method B—For Cellulose Esters Containing More than
acetone, and swirl or stir for 5 min.
30 % Propionyl or Butyryl, by Varying the Reagents
22.4 Add 30 mL of NaOH solution (40 g/L) with constant
24. Reagents
swirlingorstirringtothesolutionofthesampleandalsotothe
blank. Use of a magnetic stirrer is recommended (Note 2). It is
24.1 Acetone–Alcohol Mixture—Mix equal volumes of ac-
absolutely necessary that a finely divided precipitate of regen-
etone and methyl alcohol.
erated cellulose, free of lumps, be obtained. Stopper the flask
24.2 Hydrochloric Acid, Standard (0.5 N)—Prepare and
andletthemixturestandwithoccasionalswirlingorstironthe
standardize a 0.5 N solution of hydrochloric acid (HCl).
magnetic stirring unit. Allow 30 min for saponification of
lower acetyl samples, 2 h for high acetyl samples when 24.3 Phenolphthalein Indicator Solution (1 g/100 mL)—
Dissolve1gof phenolphthalein in 100 mL of ethyl alcohol
dimethyl sulfoxide is the solvent, and 3 h when pyridine is the
solvent.At the end of the saponification period, add 100 mLof (95%).
hotwater,washingdownthesidesoftheflask,andstirfor1or
24.4 Pyridine – Alcohol Mixture—Mix equal volumes of
2 min. Add 4 or 5 drops of phenolphthalein indicator solution
pyridine and methyl alcohol.
and titrate the excess NaOH solution with 1.0 N H SO (Note
2 4
24.5 Sodium Hydroxide, Aqueous Solution (20 g/L)—
3). Titrate rapidly with constant swirling or stirring until the
Dissolve20gofsodiumhydroxide(NaOH)inwateranddilute
end point is reached; then add an excess of 0.2 or 0.3 mL of
to 1 L with water.
H SO . Allow the mixture to stand with occasional stirring or
2 4
24.6 Sodium Hydroxide, Methanol Solution (20 g/L)—
preferably stir on the magnetic stirrer for at least 10 min.Then
add 3 drops of phenolphthalein indicator solution to each flask Dissolve 20 g of NaOH in 20 mL of water and dilute to 1 L
with methyl alcohol.
and titrate the same excess of acid with 0.1 N NaOH solution
to a persistent phenolphthalein end point.Take extreme care to
25. Procedure
locate this end point; after the sample is titrated to a faint pink
endpoint,swirlthemixturevigorouslyorplaceitforamoment
25.1 Dry the sample for2hat105 6 3°C and cool in a
on the magnetic stirrer. If the end point fades because of acid desiccator. Weigh 0.5-g portions of the sample to the nearest
soaking from the cellulose, continue the addition of 0.1 N
0.005 g and transfer to 250-mL glass-stoppered Erlenmeyer
NaOH solution until a faint persistent end point remains after
flasks. Dissolve each sample in 100 mLof appropriate solvent
vigorous swirling or stirring. Titrate the blank in the same
(see25.2and25.3)andprepareatleasttwoblanks,whichshall
manner as the sample.
be carried through all steps of the procedure.
25.2 Samples Containing 30 to 45 % Propionyl or Butyryl—
NOTE 2—While the amount of magnetic stirring is somewhat optional,
such stirring during the entire period of the determination is strongly Dissolvein100mLoftheacetone–alcoholmixture.Addwater
recommended. Solution is more rapid, titrations are more rapid, and the
and aqueous NaOH solution from a buret or pipet in the
end point can be approached directly and without a back titration.
following order and swirl the contents of the flask vigorously
NOTE 3—It is important to correct all 1.0 N H SO buret readings for
2 4
duringalladditions:10mLofNaOHsolution,10mLofwater,
temperature and buret corrections.
23. Calculation
Malm, C. J., Genung, L. B., Williams, R. F., Jr., and Pile, M.A., “Analysis of
Cellulose Derivatives: Total Acyl in Cellulose Organic Esters by Saponification in
23.1 Calculatethepercentagebyweightofacetylasfollows
Solution,” Industrial and Engineering Chemistry, Analytical Edition, IENAA, Vol
(see Note 4): 16, 1944, pp. 501–504.
D817 − 12 (2019)
10 mL of NaOH solution, 5 mL of water, 20 mL of NaOH ties encountered include ghosting in the columns, variation of
solution,and5mLofwater.Stopperandallowtostandatroom factorswithcomposition,andinconsistenciesintheuseofpure
temperature for 16 to 24 h. acids as standards. When such methods are used for this
purpose, they shall be cross checked with the following
25.3 Samples Containing More than 45 % Propionyl or
partition method using suitable check batches to establish
Butyryl—Dissolve in 100 mL of the pyridine–alcohol mixture.
accuracy.
Add 30 mLof the methanol solution of NaOH from a pipet or
28.4 This international standard was developed in accor-
buret slowly, with swirling. Add 20 mL of water slowly in
dance with internationally recognized principles on standard-
about2-mLportions,withswirling,andswirltheflaskuntilthe
ization established in the Decision on Principles for the
solution becomes turbid. Stopper and allow to stand overnight
Development of International Standards, Guides and Recom-
at room temperature.
mendations issued by the World Trade Organization Technical
25.4 Back-titrate the excess NaOH with 0.5 N HCl just to
Barriers to Trade (TBT) Committee.
the disappearance of color, using phenolphthalein indicator
solution.
29. Significance and Use
26. Calculation 29.1 Acetylandpropionylorbutyrylcontentisameasureof
the amount of each of these acids esterified onto the cellulose
26.1 Calculate the apparent acetyl content as follows:
backbone of the polymer. The amount of substitution of these
Apparentacetyl, % 5 $@~A 2 B!N 30.04305#/W% 3100 (5)
a
esters has a very strong effect on the polymer’s solubility and
physical properties.
where:
A = HCl required for titration of the blank, mL,
30. Apparatus
B = HCl required for titration of the sample, mL,
30.1 Vacuum Distillation Apparatus—The vacuum distilla-
N = normality of the HCl, and
a
W = sample used, g. tion apparatus shown in Fig. 1 will be required. The 500-mL
27. Precision and Bias
27.1 No statement on bias can be made as no reference
material is available as a standard.
ACETYL AND PROPIONYL OR BUTYRYL
CONTENTS
28. Scope
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 deter-
mined by saponifying, acidifying, vacuum distilling off the
mixture of acids, and determining the distribution ratio of the
acidsbetween n-butylacetateandwater.Thedistributionratios
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.
A—Flask containing sample (500-mL, round-bottom).
28.3 Analyses for combined acetic, propionic, and butyric
B—Capillary inlet tube.
acids may be done by gas chromatographic methods. Difficul-
C—Kjeldahl distilling head.
D—Condenser.
E—Receiver (500-mL distilling flask).
Malm, C. J., Nadeau, G. F., and Genung, L. B., “Analysis of Cellulose F—Opening for adding water.
Derivatives: Analysis of Cellulose Mixed Esters by the Partition Method,” Indus- G—Water bath for heating sample.
H—Cooling bath for receiver.
trial and Engineering Chemistry, Analytical Edition, IENAA, Vol. 14, 1942, pp.
I—Side arm, connected to vacuum line.
292–297.This reference may be consulted for application to other mixed esters and
to three-component mixtures. FIG. 1 Vacuum Distillation Apparatus for Mixed-Ester Analysis
D817 − 12 (2019)
round-bottom flask, A, shall be fitted with a stopper carrying a 25 mLof water to the residue in each flask and again distill to
very small capillary inlet tube, B, and a Kjeldahl distilling dryness.Repeatthedistillationtodrynesswithasecond25-mL
head, C. The Kjeldahl distilling head shall be connected to a portion of water.
vertical condenser, D, having an outlet tube long enough to
NOTE 5—In this operation it is not necessary to work with quantitative
reach within 76.2 mm of the bottom of the 500-mL distilling
accuracy at all stages, but it is necessary to obtain water solutions of the
flask, E,usedasareceiver.TheKjeldahldistillingheadshallbe
acids in the same ratios as they occur in the esters. The volume of the
distillate and rinsings is usually 200 to 250 mL, which in the majority of
equipped with a funnel or stoppered opening, F, for adding
cases automatically adjusts the acidity of the distillate to 0.06 to 0.12 N,
extra water during the distillation.Awater bath, G, for heating
the range desired for subsequent extractions.
the sample and a cooling bath, H, for cooling the receiver shall
32.3 Continue as directed in Section 34.
be provided.
33. Procedure B—For Samples Containing More than
31. Reagents
About 35 % Propionyl or Butyryl
31.1 Acetic, Propionic, and Butyric Acids—Acetic,
33.1 Weigh duplicate 3-g samples, not especially dried nor
propionic, and butyric acids of tested purity.
accurately weighed, into 500-mL round-bottom flasks and add
31.2 Bromcresol Green Indicator Solution (0.4 g/L)—Grind 100 mLof Formula 2B, 3A, or 30 denatured ethyl alcohol and
0.1 g of tetrabromo-m-cresolsulfonphthalein in a mortar with
100 mL of NaOH solution (20 g/L) to each flask. Allow the
14.3 mL of 0.01 N NaOH solution and dilute to 250 mL. samples to stand stoppered at room temperature for 48 to 72 h.
At the end of this period, filter off the regenerated cellulose,
31.3 n-Butyl Acetate—Prepare n-butyl acetate for use as an
collecting the filtrates in 500-mL round-bottom flasks.
extraction solvent, free of acidity and water and containing not
more than 2% butyl alcohol. Check for acidity by shaking 60 33.2 Assemble the vacuum-distillation apparatus as illus-
trated in Fig. 1. Heat the flasks in the water bath and
mL of the n-butyl acetate with 30 mL of water in a 125-mL
separatory funnel for about 1 min.Allow to settle, draw off the vacuum-distill off all the alcohol. After distilling to dryness,
releasethevacuum,rinseoutthedistillationheads,condensers,
water layer, and titrate with 0.1 N NaOH solution, using
phenolphthaleinastheindicator.Ifthisrequiresmorethan0.02 and receivers, and discard the distillates and rinsings.
mL of 0.1 N NaOH solution, the butyl acetate should be
33.3 Add the required amount, about 50 mL, of H PO
3 4
purified or a correction for acidity applied to each titration.
(1+14) to form monosodium phosphate, which liberates the
organic acids from their sodium salts. Also add 100 mL of
31.4 Ethyl Alcohol, Formula 2B, 3A, or 30 (denatured).
water to each flask and reassemble the distillation apparatus.
31.5 Phosphoric Acid (1 + 14)—Dilute 68 mL of phos-
Vacuum-distill the volatile acids as described in 32.2.
phoricacid(H PO ,85%)to1Lwithwater.TitratetheNaOH
3 4
33.4 Continue as directed in Section 34.
solution (20 g/L) with this acid to a yellow end point, using
bromcresol green indicator solution, and calculate the volume
Determination of the Molar Ratios of the Acids
of the acid (approximately 50 mL) required for 100 mL of the
NaOH solution.
34. Procedure
31.6 Sodium Hydroxide Solution (20 g/L)—Dissolve20gof
34.1 Titrate a 25-mLportion of the distillate (32.2) with 0.1
sodium hydroxide (NaOH) in water and dilute to 1 L.
N NaOH solution, using phenolphthalein as the indicator.
Designate the volume of NaOH solution required as M. Shake
31.7 Sodium Hydroxide, Standard Solution (0.1 N)—
30 mLof the distillate in a small separatory funnel with 15 mL
Prepare and standardize a 0.1 N solution of NaOH.
of n-butyl acetate. Measure these volumes accurately using
Isolation of the Mixed Acids pipets and burets. Shake the mixture thoroughly for 1 min,
allowthelayerstoseparatefor2min,anddrawofftheaqueous
32. Procedure A—For Samples Containing Less than (lower) layer. Pipet out 25 mL of the solution and titrate with
0.1 NNaOHsolution(Note6).DesignatethevolumeofNaOH
About 35 % Propionyl or Butyryl
solution required as M . Calculate K, the percentage partition
32.1 Heat duplicate 3-g portions of the sample, not espe-
ratio of the acids in the distillate, as follows:
cially dried nor accurately weighed, with 100 mL of NaOH
K 5 M /M 3100 (6)
~ !
solution (20 g/L) in 500-mL, round-bottom, chemically resis- 1
NOTE6—Itshouldbekeptinmindthatallthesedeterminationareratios
tant glass flasks in a water bath at 40°C for 48 to 72 h.At the
and not quantitative; however, accuracy of duplication is very important.
end of this time add the required amount (approximately 50
All measurements must be made as exactly as those made by standard-
mL) of H PO (1+14) to each flask to form monosodium
3 4 izations of the solutions and equipment.
phosphate, which liberates the organic acids from their sodium
34.2 In the same manner determine the distribution ratios
salts.
foracetic,propionic,andbutyricacids.Diluteasampleofeach
32.2 Assemble the vacuum distillation apparatus as illus- acid of tested purity with water to give an approximately 0.1 N
trated in Fig. 1. Heat the 500-mL round-bottom flask contain- solution. Titrate 25-mL portions and extract 30-mL portions,
ing the sample in a water bath, and vacuum-distill the acid following exactly the same procedure as used for the mixtures
solutions to dryness, allowing a small stream of air bubbles to (34.1). Calculate the partition ratios for the pure acids, as
enter to avoid bumping. Keep the receiver cooled to 0°C.Add decimal fractions, as follows (Note 7):
D817 − 12 (2019)
k 5 M /M (7)
1 C = percentages by weight of apparent acetyl (Sections 23
and 26).
where:
k = distribution ratio for acetic acid under the conditions 36.2 Hydroxyl can be measured precisely, particularly at
a
described, highdegreesofesterification(Sections38to44).Itistherefore
k = distribution ratio for propionic acid under the condi-
sometimes advantageous to base the calculation of weight
p
tions described, and
percentages of acetyl, propionyl, and butyryl on hydroxyl
k = distribution ratio for butyric acid under the conditions
b contentratherthanonapparentacetylasin36.1.Theequations
described.
for this calculation are as follows:
NOTE 7—The constants must be checked occasionally and must be
For cellulose acetate propionates:
determined by each operator for each supply of butyl acetate. Blanks
should be run on the butyl acetate, since it may develop acidity on Acetyl, % 5 9.15A 31.5 2 h / 786 2 A (17)
~ ! ~ !
standing, particularly if it contains a little water.All measurements should
Propionyl, % 5 2.93P ~31.5 2 h!/~786 2 A! (18)
be made with good pipets or burets and extreme care and cleanliness
observed during the whole operation. The accuracy of the procedure can
For cellulose acetate butyrates:
be checked by testing an acid mixture of known composition.
Acetyl, % 5 4.88A 31.5 2 h / 443 2 A (19)
~ ! ~ !
35. Calculation
Butyryl, % 5 8.05B 31.5 2 h / 443 2 A (20)
~ ! ~ !
35.1 Calculate the molar ratios of acetic and propionic or
where, in addition to the definitions of terms in 36.1:
butyric acids in the mixed acids as follows (Note 8):
h =weight percentage of hydroxyl (Section 44).
P 5 ~100k 2 K!/~k 2 k ! (8)
a a p
NOTE9—Thiscalculationinvolvestheassumptionthatthereareexactly
A 5 100 2 P (9)
three hydroxyls, free plus esterified, for each anhydroglucose unit of
B 5 100k 2 K / k 2 k (10)
~ ! ~ !
cellulose.
a a b
A 5 100 2 B (11)
37. Precision and Bias
where:
37.1 No statement on bias can be made as no reference
P = percentage of propionic acid, mol,
material is available as a standard.
B = percentage of butyric acid, mol,
A = percentage of acetic acid, mol,
HYDROXYL CONTENT
K = percentagedistributionratiooftheacidsinthedistillate
(34.1),
38. Scope
k = distribution ratio of acetic acid (34.2),
a
k = distribution ratio of propionic acid (34.2), and
38.1 This test method is applicable to pyridine-soluble
p
k = distribution ratio of butyric acid (34.2).
cellulose esters and is especially useful when the hydroxyl
b
NOTE 8—In order to evaluate two unknowns, two simultaneous
content is low. (Samples containing plasticizer may be ana-
algebraic equations involving the two unknown quantities are necessary.
lyzed directly by this test method because the plasticizer is
Inthecaseofabinaryacidmixture,thesumofthemolpercentagesofthe
removed during washing of the carbanilate).
acidspresentrepresentsthetotalacidity,or100%.If Aand Brepresentthe
mole percentages of acetic and butyric acids, respectively:
38.2 ApreferredmethodisavailableinTestMethodD5897.
A1B 5100 (12)
38.3 This international standard was developed in accor-
Ak 1Bk 5 K (13)
dance with internationally recognized principles on standard-
a b
ization established in the Decision on Principles for the
The distribution ratios k and k are known and refer to the
a b
Development of International Standards, Guides and Recom-
pure individual acids, whereas the distribution ratio K refers to
mendations issued by the World Trade Organization Technical
the binary mixture. By solving these equations for B, the
Barriers to Trade (TBT) Committee.
equations given in this section may be derived.
39. Summary of Test Method
Calculation of Acetyl, Propionyl, and Butyryl Contents
39.1 Hydroxyl in cellulose esters is determined by reaction
36. Calculation
with phenyl isocyanate in pyridine solution under anhydrous
36.1 Calculate the percentages by weight of acetyl,
conditions to form the carbanilate derivative. The derivative is
propionyl, and butyryl as follows:
then analyzed for its carbanilate content by ultraviolet absorp-
Acetyl, % 5 AC/100 (14) tion.
Propionyl, % 5 PC/100 3 57/43 (15)
~ ! ~ !
40. Significance and Use
Butyryl, % 5 BC/100 3 71/43 (16)
~ ! ~ !
40.1 Hydroxyl content is a measure of the free hydroxyl on
where:
the cellulose backbone of the polymer. Hydroxyl content has a
A = percentage of acetic acid (Section 35), mol,
strong effect on the polymer’s solubility and physical proper-
P = percentage of propionic acid (Section 35), mol,
ties. Hydroxyl content also impacts the propensity for this
B = percentage of butyric acid (Section 35), mol, and
polymer to crosslink with various crosslinking agents.
D817 − 12 (2019)
41. Apparatus 41.4 Pipet, serological type, 5-mL capacity, graduated in
0.1-mL divisions.
41.1 Spectrophotometer, complete with hydrogen light
source and a set of four 1.00-cm quartz cells or an equally 41.5 Büchner Funnel, of a size accommodating 90-mm
suitable apparatus. The wavelength calibration, as checked filter paper.
against a mercury lamp, shall be within the manufacturer’s
41.6 Automatic Shaker, with speed regulator mechanism.
tolerances. As a further check, measure the density of a
41.7 Electric Oven, maintained at 105 6 3°C.
potassium chromate (K CrO ) solution prepared as follows:
2 4
Dissolve 0.0400 g of K CrO or 0.0303 g of potassium 41.8 Oil Bath, equipped with a rack to hold several of the
2 4
dichromate (K Cr O ) in 0.05 N potassium hydroxide (KOH)
special reflux tubes. This bath shall be kept between 115 and
2 2 7
solution and dilute to 1 L in a volumetric flask with 0.05 N 120°C.
KOH solution. Using the hydrogen lamp measure the absor-
42. Reagents
bance at 280 nm of a silica cell filled with the K CrO solution
2 4
and also of the same cell filled with water. The absorbance of
42.1 Acetone.
the solution minus that of the blank shall be 0.723 6 0.023.
42.2 Ethyl Alcohol, Formula 2B, 3A, or 30 (denatured).
41.2 Bottles, 112-g (4-oz), with screw caps, for washing the
42.3 Methylene Chloride–Methyl Alcohol Mixture—Mix 9
samples.
parts by weight of methylene chloride with 1 part of methyl
41.3 Special Reflux Tubes for the carbanilation, constructed
alcohol. This mixture should have an absorbance of less than
as follows (see Fig. 2): Make a test tube approximately 20 by
0.2 at 280 nm in a 1.00-cm silica cell measured against air.
150 mm from the outer part of a standard-taper 24/40 ground-
Pure methylene chloride has an absorbance of about 0.05, but
glass joint by closing the open end in a blast lamp. Draw the
the commercial product may have an absorbance as high as
tubing on the inner joint to a constriction just above the joint.
1.00. The methylene chloride and methyl alcohol should be
Cut the glass at the point and seal on a short length of 8-mm
selected to have low absorbance; otherwise, they should be
tubing to provide a bearing for a glass stirrer. Make a stirrer of
redistilled.
4-mm glass rod with a semicircle at right angles to the shaft at
42.4 Phenyl Isocyanate.
the bottom and small enough to fit into the test tube. When
42.5 Pyridine, redistilled, of low water content, preferably
properly constructed this unit acts as an air condenser, thus
less than 0.05%.
preventing the loss of solvent by evaporation.
43. Procedure
43.1 In the following procedure the phenyl isocyanate
reagent shall be used under anhydrous conditions. Therefore,
the sample, containers, pipet, and all other equipment shall be
thoroughly dried.
43.2 Place a 0.5-g sample in a special reflux tube and dry in
an electric oven at 105 6 3°C for 2 h. Remove the tube from
the oven, add 5 mL of pyridine, assemble the reflux apparatus
complete with glass stirring rod, and place in the 115 to 120°C
oil bath. Stir occasionally until the sample is completely
dissolved. Add 0.5 mL of phenyl isocyanate, stir thoroughly,
and reflux in the oil bath for ⁄2 h to complete the reaction. Use
0.1 mL of phenyl isocyanate for each 1% of estimated
hydroxyl content, but never less than 0.5 mL.
43.3 Attheendofthereactiontime,removethesampleand
dilute it with acetone to the proper viscosity for precipitation.
The amount of acetone used to thin the solution is a critical
factor in acquiring a good precipitate. Samples having low
viscosity require little, if any, dilution. The average sample
requires the addition of about an equal volume of acetone.
Precipitate the carbanilate by pouring the solution into about
200 mL of ethyl alcohol, or if the ester contains more than
20% propionyl or butyryl, into the same volume of cold 80%
alcohol. Stir the alcohol vigorously during the precipitation.
The precipitate should be fluffy and white. Sticky precipitates
indicate too little dilution. Filter off the precipitate using paper
on a Büchner funnel, with suction applied only as long as is
necessary to remove the bulk of the solvent; prolonged suction
FIG. 2 Special Reflux Tube for Carbanilation may cause undesirable clumping together of the precipitate.
D817 − 12 (2019)
43.4 Wash the precipitate with alcohol, unless the sample Since there is also a slight reaction with secondary hydroxyls,
was precipitated in cold 80% alcohol. In this case, wash the standardized reaction conditions are important.
precipitateincold90%alcohol.Washingisbestaccomplished
47. Apparatus
by transferring the precipitate to a 4-oz screw cap bottle
containing about 75 mL of alcohol and shaking for ⁄2honan
47.1 See Section 41.
automatic shaker. Filter, pressing out as much liquid as
48. Reagents
possible with a glass stopper. Repeat the washing and filtering
operations twice more.
48.1 Acetone.
NOTE 10—Samples of high hydroxyl content and large amounts of
48.2 Ethyl Alcohol, Formula 2B, 3A, or 30 (denatured).
propionyl or butyryl may give gummy precipitates when poured into cold
48.3 Methylene Chloride-Methyl Alcohol Mixture—Mix 9
80% alcohol. Samples of this type give improved precipitates when
parts by weight of methylene chloride with 1 part of methyl
precipitated in the reverse manner. Pour the diluted reaction solution into
a 600-mL beaker, taking care to distribute the solution evenly on the
alcohol. This mixture should have an absorbance of less than
bottom. Chill the beaker in a brine bath for 30 to 60 s. Pour about 200 mL
0.2 at 259 mm in a 1-cm silica cell measured against air;
ofcold80%alcoholontothechilledliquid.Washtheresultingprecipitate
otherwise, the solvents should be redistilled.
and filter in the usual manner using cold 90% alcohol.
48.4 Pyridine, redistilled to a water content less than
43.5 Allow the precipitate to air-dry 1 to 2 h at room
0.05%. The water content may be reduced further by storing
temperature with good ventilation or preferably overnight to
over a suitable drying agent, such as a molecular sieve, Type
ensure complete removal of the alcohol. (Samples wet with
4A.
alcohol may sinter and stick to paper or glass when dried at
48.5 Trityl Chloride (Chlorotriphenylmethane or Triphenyl-
105°C.) Dry the sample at 105°C in the oven for 1 h and cool
in a desiccator. Small manila envelopes are convenient for methyl Chloride).
drying and cooling the samples.
49. Procedure
43.6 Weigh 0.1231 g of the dry precipitate into a 100-mL
49.1 The reagents must be used under anhydrous condi-
volumetric flask fitted with a ground-glass stopper. Add 60 to
tions. It is imperative that the sample and all equipment be
80 mL of methylene chloride-methyl alcohol mixture, and
thoroughly dry.
shake occasionally until complete solution occurs. Dilute to
100mLandmixthoroughly.Usingthespectrophotometerwith 49.2 Place a 0.5-g sample in the test tube of the special
a 1-cm silica cell, measure the absorbance of the solution at reflux apparatus and dry for2hat105 6 3°C. Add 5 mL of
280 nm against the solvent mixture as a reference. pyridine, insert the top of the reflux apparatus and the stirring,
and heat with stirring in a 115 to 120°C oil bath. After the
44. Calculations sample has dissolved, add 0.5 g of trityl chloride. If the total
hydroxyl content exceeds 3%, use an additional 0.075 g of
44.1 Calculate the percentage of carbanilate, c, for a sample
trityl chloride for each additional 1% hydroxyl. Stir the
weight of 0.1231 g as follows:
mixture thoroughly and reflux in the oil bath for exactly2hat
Carbanilate, % 5 A 317.1 (21)
115 to 120°C. Remove the tube and cool.
where:
49.3 Dilute the sample with acetone to the proper viscosity
for precipitation. The amount of acetone used to thin the
A = absorbance.
solution is a critical factor in obtaining a good precipitate.
44.2 Calculate the percentage of hydroxyl as follows:
Sampleshavinglowviscosityrequirelittle,ifany,dilution.The
Hydroxyl, % 5 14.3c/~100 2 c! (22)
average sample requires the addition of about an equal volume
of acetone. Precipitate the trityl derivative by pouring the
45. Precision and Bias
solution into about 200 mL of ethyl alcohol with vigorous
stirring. The precipitate should be fluffy and white. Sticky
45.1 No statement on bias can be made as no reference
precipitates indicate too little dilution. Separate the precipitate
material is available as a standard.
by filtering through paper on a Büchner funnel, with suction
PRIMARY HYDROXYL CONTENT applied only as long as necessary to remove the bulk of the
solvent; prolonged suction may evaporate the alcohol and
46. Summary of Test Method cause the precipitate to partially redissolve in the remaining
pyridine.
46.1 The primary hydroxyl content of cellulose ester is
49.4 Wash the precipitate by transferring it to a 4-oz screw
determined by formation of the triphenylmethyl (trityl) ether
capbottlecontaining75mLofethylalcohol,cappingsecurely,
andmeasurementofthetritylgroupbyultravioletabsorbance.
and shaking for ⁄2 h on a shaker at medium speed. Again
Trityl chloride reacts preferentially with primary hydroxyls.
collect the precipitate on a Büchner funnel, pressing out as
6 7
Malm, C. J., Tanghe, L. J., Laird, B. C., and Smith, G. D., “Determination of Malm, C. J., Tanghe, L. J., and Laird, B. C., “Primary Hydroxyl Groups in
Total and Primary Hydroxyl in Cellulose Esters by Ultraviolet Absorption HydrolyzedCelluloseAcetate,” Journal of the American Chemical Society,JACSA,
Methods,” Analytical Chemistry, ANCHA, Vol 26, 1954, p. 189. Vol 72, 1950, p. 2674.
D817 − 12 (2019)
much liquid as possible with a glass stopper. Repeat this 53. Apparatus
washing and filtering operation twice more, or until the
53.1 Funnel, modified by cutting the stem off at the apex of
absorbanceofthefiltrateat259nmisaboutthesameasthatof
the funnel and fire polishing.
an alcohol blank. Allow the precipitate to air-dry on the filter
53.2 Crucibles, 30-mL, extra-fine porosity.
paper for ⁄2 h at room temperature with good ventilation, or
preferably overnight, to remove most of the alcohol. (Samples 53.3 Oven, controlled at 120 to 125°C.
wet
...