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.

D297 − 15 (2019)
Designation: D297 − 15 (Reapproved 2019)
filler unless a correction can be made for losses of water of 9.3 In the absence of milling machinery, the sample may be
hydration on ashing. This correction can be made only if the prepared by cutting it with scissors so that it will pass a No. 14
nature and quantity of these fillers are known. The indirect test (1.40-mm) sieve.6,7 The sample may be cut into long strips that
method will not give accurate results in the presence of are fine enough to pass freely through the sieve and the strips
Standard Test Methods for halogen-containing components or silicone rubber. In the fed through by hand, or the sample may be cut into small
Rubber Products—Chemical Analysis1 presence of antimony sulfide or carbonates decomposing at fragments and shaken through the sieve. The cutting shall be
550°C, but in the absence of the above interfering constituents, continued until the entire sample passes through the sieve. If
This standard is issued under the fixed designation D297; the number immediately following the designation indicates the year of approximate correction can be made by means of determina- necessary, to prevent sticking, different fragments of the sieved
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A tion of total antimony (Section 50) or of the metal associated sample may be segregated by wrapping in a liner material that
superscript epsilon (´) indicates an editorial change since the last revision or reapproval. with the decomposable carbonate (usually calcium, Section 45) will not adhere to or contaminate the sample.
This standard has been approved for use by agencies of the U.S. Department of Defense. or (Section 49) and calculation of the original composition of 9.4 Certain very glutinous samples may be prepared for
the compounding ingredient from these data. extraction analysis as follows: Place a weighed 2-g sample of
1. Scope 2. Referenced Documents 6.5 If factice or high percentages of mineral rubber are the material between two pieces of ashless filter paper that has
present, no accurate test method is known for determination of been extracted in accordance with Section 21. The papers
1.1 These test methods cover the qualitative and quantita- 2.1 ASTM Standards:2 rubber content or for complete analysis of the rubber product. should be approximately 500 by 100 mm (20 by 4 in.) and the
tive analysis of the composition of rubber products of the “R” D982 Test Method for Organic Nitrogen in Paper and sample should be placed near one end. Flatten the sample and
family (see 3.1). Many of these test methods may be applied to 6.6 For the determination of the rubber content of hard
Paperboard rubber products, no accurate test method is described herein if spread it throughout the length of the filter paper by passing the
the analysis of natural and synthetic crude rubbers. D1416 Test Methods for Rubber from Synthetic Sources— “sandwich” lengthwise, through a cold, closely set, even-speed
1.1.1 Part A consists of general test methods for use in the fillers decomposable at 550°C are present.
Chemical Analysis (Withdrawn 1996)3 rubber calender. The gross thickness of the resulting sheet
determination of some or all of the major constituents of a D1418 Practice for Rubber and Rubber Latices— should not be greater than 1.0 mm. If a rubber calender is not
7. Blank Determinations
rubber product. available, a similar sheet may be obtained by placing the
Nomenclature
1.1.2 Part B covers the determination of specific polymers 7.1 Blanks shall be run on all determinations to check the sample in a hydraulic press or a vise. In the latter case, the
D1646 Test Methods for Rubber—Viscosity, Stress purity of the materials used and deductions shall be made
present in a rubber product. sample may be roughly spread by hand throughout the length
Relaxation, and Pre-Vulcanization Characteristics accordingly.
1.1.3 The test methods appear in the following order: of the filter paper and pressure applied to small areas at a time
(Mooney Viscometer)
Part A. General Test Methods: Sections
D3040 Practice for Preparing Precision Statements for Stan- until the whole sample has been flattened.
Rubber Polymer Content by the Indirect Method 11 – 13
8. Check Analyses
Determinations and Report for the General Method 14 and 15 dards Related to Rubber and Rubber Testing (Withdrawn 9.5 Samples of rubberized cloth, whose overall thickness is
8.1 Duplicate determinations shall be made and shall check
Density 16 1987)3 no greater than 1.0 mm, may be prepared for analysis by
Extract Analysis 17 – 26 within the limits specified in the test method, when these are
D3156 Practice for Rubber—Chromatographic Analysis of cutting them into pieces 1.5 mm square and then mixing well.
Sulfur Analysis 27.1 – 33 stated.
Fillers Analysis 34 – 40 Antidegradants (Antioxidants, Antiozonants and Stabiliz- If the fabric is easily removed, it should be separated, unless an
Ash Analysis 41 – 51 ers) 9. Preparation of Samples analysis of the whole cloth is desired.
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Part B. Determination of Rubber Polymers 52 – 58

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D3452 Practice for Rubber—Identification by Pyrolysis-Gas 9.6 Samples of rubber cements shall be evaporated to
1.2 The values stated in SI units are to be regarded as Chromatography 9.1 Before preparing a sample for analysis, the analyst shall,
by inspection, assure himself that it has not been contaminated. dryness in a vacuum oven at a temperature not higher than
standard. The values given in parentheses are for information D3677 Test Methods for Rubber—Identification by Infrared 30°C. The residue may then be analyzed as an unvulcanized
only. The sample to be analyzed shall be selected by taking pieces
Spectrophotometry sample. A separate sample of the cement shall be distilled
from various parts of the original sample and separating them
1.3 This standard does not purport to address all of the D4483 Practice for Evaluating Precision for Test Method under reduced pressure if examination of the solvent is desired.
from foreign matter. Because of the variety of rubber products
safety concerns, if any, associated with its use. It is the Standards in the Rubber and Carbon Black Manufacturing
to which this test method can be applied, no single procedure 9.7 Samples of hard rubber shall be reduced to powder form
responsibility of the user of this standard to establish appro- Industries for reducing the sample to the required fineness is applicable to by filing, cleaned with a magnet, and sieved through a No. 30
priate safety, health, and environmental practices and deter- E11 Specification for Woven Wire Test Sieve Cloth and Test all samples. Therefore, several alternative procedures for this (600-µm) sieve.6 Residue retained on this sieve shall be
mine the applicability of regulatory limitations prior to use. Sieves purpose are described in 9.2 to 9.7. The analyst is expected to reduced until the entire sample passes through the sieve.
Specific precautionary or warning statements are given in E131 Terminology Relating to Molecular Spectroscopy select the one most suitable to the sample that he is analyzing
31.4.5, 31.6, 37.4.2, 38.4.2, 45.1.3, 53.2.3.5, 54.4.2, 54.6, E200 Practice for Preparation, Standardization, and Storage 10. Preliminary Examination of Samples
and the equipment available.
56.5.3, and 57.7.3; and X1.3.3 and X2.4.1.6. of Standard and Reagent Solutions for Chemical Analysis
9.2 For vulcanized soft rubber, unvulcanized rubber, crude 10.1 The procedures given in 10.1.1 – 10.1.9 are for use in
1.4 This international standard was developed in accor- E442 Test Method for Chlorine, Bromine, or Iodine in
rubber, and many samples of reclaimed rubber, it is preferable determining the number and kind of tests that should be
dance with internationally recognized principles on standard- Organic Compounds by Oxygen Flask Combustion (With-
to mix the sample and grind it by passing it two or three times conducted to obtain the desired information concerning the
ization established in the Decision on Principles for the drawn 1996)3
through a clean, cold, laboratory rubber mill. The rubber will rubber product.
Development of International Standards, Guides and Recom-
E443 Test Method for Sulfur in Organic Compounds by 10.1.1 Carbonates—Drop a small piece of sample into a test
mendations issued by the World Trade Organization Technical come from the mill in the form of a coarse powder or a rough
Oxygen Flask Combustion (Withdrawn 1996)3 sheet. If the product is in the form of a sheet, the adjustment of tube containing HCl saturated with bromine. If a stream of
Barriers to Trade (TBT) Committee.
the mill shall be such that the thickness of the final sheet is no bubbles is given off, carbonates are present. The test is not
greater than 0.5 mm. If the sample is sticky, it shall be rolled applicable to IIR products.
1
These test methods are under the jurisdiction of ASTM Committee D11 on 2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or in a liner material that will not adhere to or contaminate the 10.1.2 Antimony and Lead—Ash a 0.2 to 0.3-g specimen in
Rubber and Rubber-like Materials and are the direct responsibility of Subcommittee contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM sample. If the milled sample is a powder, it shall be transferred accordance with 35.4 or 36.4. Dissolve the ash in 10 cm3 of
D11.11 on Chemical Analysis. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Dec. 1, 2019. Published December 2019. Originally the ASTM website.
to a No. 14 (1.40-mm) sieve5 and rubbed through the sieve.
approved in 1928. Last previous edition approved in 2015 as D297 – 15. DOI: 3
The last approved version of this historical standard is referenced on Grinding shall be continued until the entire sample passes 6
The sole source of supply of compressed volume densimeters known to the
10.1520/D0297-15R19. www.astm.org. through the sieve. committee at this time is C. W. Brabender Instruments, Inc., 50 E. Wesley St., South
Hackensack, NJ 07606.
7
If you are aware of alternative suppliers, please provide this information to
ASTM International Headquarters. Your comments will receive careful consider-
5
Detailed requirements for these sieves are given in Specification E11. ation at a meeting of the responsible technical committee,1 which you may attend.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States

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acetone extract, based on rubber as compounded, % (5) Determined TABLE 2 Compressed Volume Density, Type 1—PrecisionA
Percentage of by Section NOTE 1—Measured Property = Density, Mg/m3.
5 ~ A/B ! 3 100 (26) Barium sulfate 48
(27) Antimony sulfide 50 Within Laboratories Between Laboratories
Material Average
where: (28) Titanium dioxide 51 Sr r (r) SR R (R)
A (SBR1500) 0.944 0.00078 0.00217 0.23 0.00117 0.00328 0.35
A = percentage of acetone extract, and DENSITY B (SBR1712) 0.954 0.00100 0.00280 0.29 0.00148 0.00413 0.43
B = percentage of rubber as compounded. C (SBR1848) 1.134 0.00071 0.00198 0.17 0.00194 0.00542 0.48
Pooled (average) 1.011 0.00084 0.0024 0.23 0.00156 0.00440 0.44
14.1.2 Sulfur Based on Rubber as Compounded—Calculate 16. Density A
The time period for precision is days.
the percentage of sulfur, based on rubber as compounded, as 16.1 Determine the density by use of a pycnometer, by
follows: hydrostatic weighings, or by compressed volume densimeter.
Sulfur, based on rubber as compounded, % 5 ~ A/B ! 3 100 (6) All determinations must be made with solutions at room
temperature. Make appropriate corrections to the calculation if as indicated by two or more identical readings in succession of test result is the value obtained from the average of three
where:
the room is at a temperature other than 25°C. Report the the output from the linear displacement transducer. Note the determinations. Each material was analyzed in triplicate on two
A = percentage of total sulfur, and total piston displacement value in centimeter 60.001. separate days.
temperature of the room when the determinations were made.
B = percentage of rubber as compounded. 16.4.8 Calculation: 16.4.10.3 Precision parameters are given in Table 2.
14.1.3 Inorganic Fillers—The inorganic fillers may be de- 16.2 Pycnometer Method:
16.4.8.1 Calculate the sample’s compressed volume as fol- 16.4.10.4 The difference between two single test results (or
termined as a unit or may be determined individually and 16.2.1 Procedure—Determine the density using the pyc- lows: determinations) found on identical test material under the
reported as in Items (18) to (28) of 15.1. nometer with alcohol in place of water to eliminate errors due repeatability conditions prescribed for a particular test will
to air bubbles. Vs 5 k 3 D 2 3 L (9)
14.1.4 Combustible Fillers—Carbon black and glue are the exceed the repeatability on an average of not more than once in
combustible fillers which may be determined individually. 16.2.2 Calculation—Calculate the density as follows: where: 20 cases in the normal and correct operation of the test method.
14.1.5 Additives—Additives such as factice, other rubber 0.9971 3 A Vs = compressed volume, cm3, 16.4.10.5 The difference between two single independent
substitutes, and softeners are not accurately determined. Their Density at 25°C in Mg/m 3 5 3D (7) D = test cylinder diameter, cm,
A 2 ~B 2 C! test results found by two operators working under the pre-
presence and an estimate of the quantities present may be L = thickness of compressed sample, cm, and scribed reproducibility conditions in different laboratories on
found by determination of acetone, chloroform and alcoholic where: k = 0.0784. identical test material will exceed the reproducibility on an
potash extracts, unsaponifiable matter, waxy hydrocarbons, and A = mass of specimen, g, average of not more than once in 20 cases in the normal and
16.4.8.2 Calculate the sample density as follows:
mineral oil, and these values shall be reported in a complete B = mass of pycnometer filled with specimen and alcohol, correct operation of the test method.
g, Wo
analysis. D, Mg/m 3 5 (10) 16.4.11 Keywords:
C = mass of pycnometer filled with alcohol, g, and Vs
16.4.11.1 compressed volume; densimeter; density; mass;
D = density of alcohol (25°C), Mg/m3 (gm/cc).
15. Report where: mass/volume ratio
15.1 The report may include any or all of the following 16.3 Hydrostatic Method: D = compressed density (see Note 4),
16.3.1 Procedure—Weigh the specimen first in air. Weigh to Wo = sample mass, g, and EXTRACT ANALYSIS
Items (1) to (17) if a detailed filler analysis is not desired; the
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purpose of the analysis shall determine the nature of the report. the nearest 0.1 mg for specimens of mass 1 to 10 g or density Vs = sample volume, cm3. 17. Scope
less than 1.00 g/cm. Weigh to the nearest 1 mg for larger NOTE 4—Mg/m3 is numerically equal to gm/cm3.
The report may also include any or all of the following Items
specimens or those with density greater than 1.00. 17.1 The test methods described in Sections 18 – 26 cover
(18) to (28) if a detailed analysis of inorganic filler is desired. 16.4.9 Report the following information:
16.3.2 Suspend in water and weigh again. Dipping of the the removal from a rubber product of all nonrubber constitu-
Determined 16.4.9.1 Date of test,
specimen in alcohol followed by blotting before suspending in ents soluble in specified organic solvents.
Percentage of by Section 16.4.9.2 Sample identification,
water for weighing will aid in the elimination of bubbles that 16.4.9.3 Test temperature, 18. Terminology
(1) Acetone extract, corrected 18.1 and 19
(2) Waxy hydrocarbons 24
cause errors in the determination. A very fine wire is recom- 16.4.9.4 Type of compressed volume densimeter, include
(3) Mineral oil 25 mended as a supporting medium. critical dimensions if different from those of Fig. 1, and 18.1 Definitions of Terms Specific to This Standard:
(4) Chloroform extract 18 16.3.3 Calculation—Calculate the density as follows: 16.4.9.5 Results calculated in accordance with Eq 9 and Eq 18.1.1 acetone extract—If the acetone extract is made on
(5) Free sulfur 29
10. vulcanized rubber products the acetone removes rubber resins,
(6) Combined sulfur 28.2.1 0.9971 3 A
(7) Total sulfur 28.2.4 Density at 25°C in Mg/m 3 5 (8) 16.4.10 Precision and Bias:8 free sulfur, acetone-soluble plasticizers, processing aids, min-
A 2 ~B 2 C! eral oils or waxes, acetone-soluble antioxidants and organic
(8) Fillers, inorganic 34.1 16.4.10.1 These precision statements have been prepared in
(9) Carbon black 38 or 39
where: accordance with Practice D4483. Refer to Practice D4483 for accelerators or their decomposition products, and fatty acids. It
(10) Glue 40
(11) Rubber polymer 11 – 13 or 52 – A = mass of specimen, g, terminology and other statistical calculation details. also removes part of bituminous substances, vulcanized oils,
58 B = mass of specimen and supporting wire in water, g, and 16.4.10.2 The results presented in Table 2 give an estimate high molecular mass hydrocarbons, and soaps. This is gener-
(12) Rubber polymer by volume 11 – 13
of the precision of this test method with the SBR rubbers used ally called acetone extract. The percentages of free sulfur,
(13) Rubber as compounded, natural or syn- 11 – 13
thetic C = mass of supporting wire in water, g. in the interlaboratory program described below. These preci- waxy hydrocarbons, and mineral oil are determined and their
(14) Rubber by volume, natural or synthetic 11 – 13 sion parameters should not be used for acceptance or rejection sum deducted from the acetone extract. The value obtained is
(15) Percentage of acetone extract on rubber 16.4 Compressed Volume Densimeter: known as acetone extract, corrected. The corrected figure thus
as compounded 14.1.1 testing of materials without documentation that they are
16.4.1 Scope—This test method describes the use of a obtained will at times give valuable information regarding the
(16) Percentage of sulfur on rubber as com- 14.1.2 applicable to those particular materials and the specific testing
pounded volume compressing densimeter which operates on a “Sample quality of the rubber present. This is not true, however, when
protocols that include this test method.
(17) Density 16 Mass versus Compressed Sample Volume” ratio as a means of the product contains substantial quantities of mineral oils or
(18) Silicon dioxide and insoluble matter 42 (1) Type 1 interlaboratory precision program was con-
determining the density of rubbery materials such as raw waxes, bituminous substances, organic accelerators, or antioxi-
(19) Silicon dioxide 42 ducted. A period of 24 h separates replicate test results. Five
(20) Lead oxide 43 rubbers, carbon black masterbatches, or vulcanizable finished dants. With products containing rubber that consists of only the
laboratories participated and three SBR rubbers were used. A
(21) Iron and aluminum oxides 44 compounds in the uncured state. best grades of Hevea rubber, the acetone extract should not
(22) Calcium oxide 45
(23) Magnesium oxide 46
16.4.2 Terminology: exceed 5 % of the rubber present. A higher extract may indicate
(24) Zinc oxide 47 16.4.2.1 compressed volume—The final equilibrium volume 8
Supporting data have been filed at ASTM International Headquarters and may the presence of inferior or reclaimed rubbers, added oils,
(25) Barium carbonate 49 attained by an unvulcanized rubber sample when it is subjected be obtained by requesting Research Report RR:D11-1061. waxes, or bituminous materials, or substantial quantities of

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 D297 − 15 (2019) D297 − 15 (2019)
19.4.4 Cool in a desiccator to the temperature of the balance 23.3.1 Add to the acetone extract obtained from a 2-g 24.4 Calculation—Calculate the percentage of waxy hydro-
and weigh. specimen (see 19.4), 50 cm3 of a 1 N alcoholic KOH solution, carbons as follows:
19.5 Calculation—Calculate the percentage of acetone ex- condenser for 2 h, remove the condenser, and evaporate to Waxy hydrocarbons, % 5 ~ A/B ! 3 100 (16)
tract as follows: dryness.
23.3.2 Transfer to a separatory funnel, using about 100 cm3 where:
Acetone extract, % 5 ~ A/B ! 3 100 (11) A = mass of waxy hydrocarbons, and
of water. Extract with 25 cm3 of ether. Allow the layers to
where: separate thoroughly; then draw off the water layer. Continue B = grams of specimen used.
A = grams of extract, and extraction of the water layer with fresh portions of ether,
including washing out the original flask with a portion, until no 25. Mineral Oil
B = grams of specimen used.
more unsaponifiable matter is removed. This usually requires 25.1 Scope—This test method covers the determination of
20. Chloroform Extract about four washings. Unite the ether layers and wash with the amount of mineral oil that is extracted from a rubber
water until a negative test for alkali using phenolphthalein product with acetone. The mineral oils found are saturated
20.1 Scope—This test method covers the determination of
indicator is obtained on the wash water. hydrocarbons that are soluble in ethanol at −5°C, are soluble in
the amount of material removed from a vulcanized rubber
23.3.3 Transfer the ether to a weighed flask and distill off CCl4, and are not attacked by concentrated H2SO4.
product by extraction with chloroform after the specimen has
been extracted with acetone (see 18.2). Its application is the ether on a steam bath using a gentle stream of filtered air to 25.2 Reagents:
restricted to vulcanized NR, SBR, BR and IR types of rubber prevent boiling. Continue the air stream for 5 min after the 25.2.1 Carbon Tetrachloride (CCl4).
products. ether is distilled off. Dry the extract to constant mass at 100 6 25.2.2 Ether.
5°C and weigh. Save the residue for determination of waxy 25.2.3 Sulfuric Acid (H2SO4).
20.2 Apparatus—The extraction apparatus shall be that hydrocarbons (Section 24) and mineral oil (Section 25).
described in 19.2. 25.3 Procedure—Evaporate the alcohol filtrate from the
23.4 Calculation—Calculate the percentage of unsaponifi- waxy hydrocarbon determination (24.2.1), using a gentle
20.3 Solvent: Chloroform—Chloroform of USP grade may
able acetone extract as follows: current of filtered air to prevent boiling, add 25 cm3 of CCl4,
be used in extraction.
Unsaponifiable acetone extract, % 5 ~ A/B ! 3 100 (15) and transfer to a separatory funnel. Shake with H2SO4, drain
20.4 Procedure: off the colored acid, and repeat with fresh portions of H2SO4
20.4.1 Suspend the extraction cup containing the specimen where: until there is no longer any discoloration of the acid. After
FIG. 3 Extraction Apparatus with Glass Condenser that has been extracted with acetone (19.4) in a second A = grams of extract, and drawing off all of the H2SO4, add a portion of water and
weighed extraction flask containing 50 to 75 cm3 of chloroform B = grams of specimen used. sufficient ether to form the ether-CCl4 layer above the water
and extract it for 4 h with the chloroform, using the extraction and wash repeatedly with water until all traces of acid are
19.2.2 The apparatus in Fig. 2 shall consist of a glass
rate prescribed in 19.4. (Rubber products having a ratio of total 24. Waxy Hydrocarbons removed as shown by a methyl red indicator test on the water
conical flask, glass extraction cup, and block tin condenser.
sulfur to rubber polymer in excess of 10 % shall be extracted layer. Transfer the ether-CCl4 layer to a weighed flask and
The apparatus in Fig. 3 shall be all glass. 24.1 Scope—This test method covers the determination of
for 24 h.) Record the color of the chloroform solution. evaporate the solvent on a steam bath, using a current of
19.3 Solvent: Acetone—USP grade acetone may be used if 20.4.2 Evaporate the chloroform over a steam bath, using a the amount of waxy hydrocarbons contained in the unsaponi-
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filtered air to prevent boiling. Remove from the steam bath just
distilled over anhydrous potassium carbonate (K2CO3) not gentle current of filtered air to prevent boiling. Remove the fiable acetone extract that are soluble in ethanol and that
prior to the disappearance of the last traces of solvent and
more than 10 days before use. Use the fraction boiling between flask from the steam bath just prior to the disappearance of the separate from an ethanol solution on cooling to −5°C.
continue the flow of air for 10 min. Dry to constant mass in an
56 and 57°C. last traces of solvent to prevent loss of extract. Continue the 24.2 Reagents: air bath at 100 6 5°C, cool, and weigh.
19.4 Procedure: passage of air for 10 min to remove the remaining solvent and 24.2.1 Chloroform—See 20.3. 25.4 Calculation—Calculate the percentage of mineral oil
19.4.1 Place a weighed specimen of approximately 2 g in a dry the flask for 2 h in an air bath at 70 6 5°C. 24.2.2 Ethanol, Absolute. as follows:
filter paper. If the specimen is in the form of a sheet (see 9.2), 20.4.3 Cool in a desiccator to the temperature of the balance
24.2.3 Ethanol (95 to 100%). Mineral oil, % 5 ~ A/B ! 3 100 (17)
cut it with scissors into strips 3 to 5 mm in width. If the and weigh. Reserve the extracted sample for extraction with
specimen becomes tacky during the extraction, take care that alcoholic potash (Section 22). 24.3 Procedure: where:
adjacent portions are separated by paper. Fold the paper so that 20.5 Calculation—Calculate the percentage of chloroform 24.3.1 To the unsaponifiable matter, obtained from 23.3.3, A = grams of residue, and
it will fit in the extraction cup and suspend the cup in a weighed extract as follows: add 50 cm3 of absolute ethanol and heat on the steam bath for B = grams of specimen used.
extraction flask containing 50 to 75 cm3 of acetone. (Prior to 30 min. Let the flask stand in a mixture of ice and salt kept at
Chloroform extract, % 5 ~ A/B ! 3 100 (12)
the weighing of the extraction flask, it shall have been dried for −5°C for at least 1 h. Filter off the separated waxy hydrocar- 26. Rapid Reflux Extracts
2 h at 70 6 5°C and cooled in a desiccator to the temperature where: bons on filter paper by applying gentle suction while keeping
26.1 Scope—This test method covers the determination of
of the balance.) A = grams of extract, and the filter funnel surrounded by a salt-ice mixture at −5°C or
the amount of material removed from a vulcanized product by
19.4.2 Extract the specimen continuously for 16 h heating at B = grams of specimen used. lower. Wash the precipitate with ethanol (95 to 100 %) that has
rapid reflux extraction with a specified solvent or the removal
a rate such that the time required to fill and empty the siphon been cooled to −5°C or lower in an ice-salt mixture. Save the
of extractable material from a rubber product that is to be
cup will be between 2.5 and 3.5 min. (Rubber products having 21. Total Extract filtrate and washings for determination of mineral oil (Section
analyzed further (see 18.8). It is applicable only to vulcanized
a ratio of total sulfur to rubber polymer in excess of 10 %, shall 25).
21.1 Scope—The total extract (see 18.3) may be used to NR, SBR, BR, IR, and IIR products and is used when the
be extracted for 72 h.) Carefully note all characteristics of the replace the sum of the acetone and chloroform extracts when 24.3.2 Dissolve the precipitate from the filter paper with hot extracts themselves are not to be analyzed further. The values
extract, when hot and cold. analysis is to be performed on an extracted specimen or when chloroform, and catch the solution in a weighed 100 to obtained are not necessarily equivalent to those obtained by
19.4.3 Evaporate off the acetone over a steam bath, using a rubber polymer is being determined in accordance with 13.1. 150-cm3 beaker. Wash the flask with hot chloroform and add continuous extraction procedures (Sections 19, 20, and 21).
gentle current of filtered air to prevent boiling. Remove the Its application is restricted to vulcanized NR, SBR, BR, and IR the washings to the solution in the beaker in order to include
flask from the steam bath just prior to the disappearance of the any insoluble matter adhering to the walls of the flask. 26.2 Reagents:
types of rubber products. 26.2.1 Acetone.
last traces of solvent to prevent loss of extract. Continue the Evaporate the solvent on a steam bath, passing a gentle current
passage of air through the flask for 10 min to remove the 21.2 Apparatus—The extraction apparatus shall be that of filtered air over the residue for 5 min after the solvent is 26.2.2 Methyl Ethyl Ketone.
remaining solvent and dry the flask for 2 h at 70 6 5°C in an described in 19.2. essentially evaporated. Dry to constant mass at 100 6 5°C, 26.3 Procedure—Mill the sample until a homogeneous
air bath. 21.3 Reagents: cool, and weigh. sheet not more than 0.75 mm (0.030 in.) thick is formed. Cut

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28.2.3 sulfur, acetone extract—the sulfur removed from a precipitate by filtration, using a Büchner funnel with suction TABLE 3 Basic Test Precision Data 31.7.13 Add 100 cm3 of isopropanol (or sufficient to make
rubber by extraction with acetone (Section 19) or acetone- (see 29.2.1). Wash with two 75 to 100-cm3 portions of Within Among the solution 80 % in isopropanol by volume), two drops of
chloroform mixture (Section 21). This method determines cadmium acetate wash solution. Sample Mean Laboratories Laboratories Thorin solution and the stirring bar to the beaker, place a
S CV S CV
elemental sulfur, sulfur in solvent-soluble accelerators and part 29.4.2 To the filtrate add, while stirring, 10 cm3 of formal- 1 0.93 0.0439 0.0456 0.1513 0.1631 high-intensity lamp (if desired) against the beaker and titrate
of the sulfur present in factice, mineral rubber, reclaimed dehyde solution, 10 cm3 of glacial acetic acid, and 5 cm3 of 2 23.39 0.7654 0.0315 0.9970 0.0426 with Ba(ClO4)2 dropwise from the buret until the yellow color
rubber, and extender oils. It does not determine free sulfur, and starch solution. Add enough crushed ice to bring the tempera- 3 45.22 1.2893 0.0283 2.9877 0.0661 changes to a pink color, which remains for at least 30 s.
Repeatability Reproducibility
the inclusion of the method is largely for the purpose of ture of the solution below 15°C, and titrate with 0.05 N iodine Standard deviation (S) 0.5568A 1.8834A Alternatively, Chlorophosphonazo III (31.4.3) may be used as
detecting the presence of sulfur-bearing rubber substitutes such solution to a blue end point. Coefficient of variation
0.0359 0.1091
the indicator. Use 1 cm3 per analysis. Titrate from a lavender-
as factice and mineral rubber, or for detecting the presence of (CV) pink to a green-blue end point. Use a high-intensity lamp if
29.5 Blank—The blank determination on the reagents Least significant
an unusually large amount of elemental sulfur or accelerators. should not exceed 0.2 to 0.3 cm3. difference (LSD)
10.2 30.8 B
desired. Read the buret value to 0.01 cm3.
It shall be determined in accordance with Section 30. A
LSD is based on 95 % confidence limits. 31.7.14 Obtain a blank determination by carrying out the
29.6 Calculation—Calculate the percentage of free sulfur as B
An average value, the Standard deviation varies with the test level. See table of entire procedure without using a rubber sample.
28.2.4 total sulfur—all the sulfur present in a rubber com-
follows: values.
pound. The total sulfur shall be determined in accordance with 31.8 Calculations:
Section 31 in the absence of barium sulfate, acid-soluble Free sulfur, % 5 ~ A 2 B ! N 3 0.032/C 3 100 (21) 31.8.1 Calculate the total sulfur as follows:
barium salts, inorganic lead compounds, and antimony com- where: Total sulfur, % 5 @ ~ A 2 B ! M 3 3.21# /W (22)
pounds. Section 32 must be used on compounds containing any A = volume of iodine solution required for titration of the
of the above inorganic compounds. 31.7.4 Fold the paper in accordance with 8.2.4 and 8.2.5 of where:
sample, cm3, Test Method E443, place the folded paper firmly in the
B = volume of iodine solution required for titration of the A = Ba(ClO4)2 solution required for titration of the
29. Free Sulfur platinum sample carrier hung on the hook of the stopper with
blank, cm3, sample, cm3,
the pointed end of the paper projecting outward. B = Ba(ClO4)2 solution required for titration of the blank,
29.1 Scope—This test method covers the determination of N = normality of the iodine solution, and 31.7.5 Insert a tube from the oxygen cylinder to nearly the cm3,
the amount of free sulfur (see 28.2.2) in rubber products. It is C = grams of sample used. bottom of the flask as in Fig. 2, A, of Test Method E443 and M = molarity of the Ba(ClO4)2 solution, and
applicable to NR, SBR, BR, NBR, CR, and IR products.
blow in oxygen strongly for at least 0.5 min. W = mass of sample used, g.
30. Sulfur, Acetone Extract
29.2 Apparatus: 31.7.6 Smoothly remove the oxygen tube and close the
29.2.1 Filter Crucibles, filter crucibles that will withstand 30.1 Scope—This test method covers the determination of stopper without letting the platinum carrier drop into the liquid. 31.9 Precision:19
the firing temperature required in the specific application. the amount of sulfur in the acetone extract. It is applicable to 31.7.7 With the stopper upright, clamp the stopper tightly 31.9.1 These precision statements have been prepared in
NR, SBR, BR, IR, and CR products and to IIR products if the with the pinch clamp. accordance with Practice D3040. Please refer to this practice
29.3 Reagents and Materials: for terminology and other testing and statistical concept
extraction is made with methyl ethyl ketone instead of acetone. 31.7.8 Place the flask in the infrared igniter chamber with
29.3.1 Cadmium Acetate Solution (30 g/dm3). explanations.
The analysis shall be performed on an acetone extract prepared the pointed end of the paper in line with the infrared beam and
29.3.2 Cadmium Acetate Wash Solution (1.2 g/dm3). 31.9.2 The basic test precision is estimated from an inter-
as described in Section 19. approximately perpendicular to it. Close the door and turn on
29.3.3 Formaldehyde Solution (40 %). laboratory study by four laboratories testing three materials on
29.3.4 Glacial Acetic Acid. 30.2 Reagents: the infrared light (or electric igniter) until the paper ignites.
four days.
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29.3.5 Iodine, Standard Solution (0.05 N)—Add 6.35 g of 30.2.1 Bromine. 31.7.9 After ignition, stir the sealed flask vigorously on a
magnetic stirrer for 1 h. Alternatively, it may be allowed to 31.9.3 A test result is a single determination. See Table 3.
iodine and 20 g of potassium iodide (KI) to a beaker and just 30.2.2 Nitric Acid, Fuming.
cover with water. Let stand with occasional stirring until 30.2.3 Zinc-Nitric Acid Solution—Add 200 g of zinc oxide stand undisturbed for 2 h.
32. Sulfur, Fusion Test Method
dissolved, adding a small additional amount of water if (ZnO) to 1 dm3 of HNO3 slowly and with caution. Use 31.7.10 Remove the pinch clamp, tilt the stopper to release
necessary. When dissolved, dilute to 1 dm3, filter through a protection for the face and hands. the vacuum, and open the flask. 32.1 Scope—This test method covers the determination of
filter crucible, and store the solution in a stoppered, brown 31.7.11 If substantial amounts of compounds of zinc or total, combined plus inorganic, or inorganic sulfur in rubber
30.3 Procedure—Add to the flask containing the acetone compounds when acid-soluble barium salts, antimony sulfide,
glass bottle. Standardize, preferably on the day it is to be used, other cations are thought or known to be present in the
extract, 10 cm3 of Zn-HNO3 solution and 2 to 3 cm3 of bromine or inorganic lead compounds are present. All of the sulfur in
against the National Institute of Standards and Technology compound, prepare an ion exchange column and pass the
and cover with a watch glass. Allow to stand near a steam plate the specimen, including that present in BaSO4, is determined
standard sample No. 83 of arsenic trioxide in accordance with solution through it.
for 30 min; then heat on the steam plate to a foamy syrup. Add by this test method. It must be used for determinations of total
the instructions furnished with the standard sample. 31.7.11.1 Place a wad of glass wool about 13 mm (0.5 in.)
10 cm3 of fuming HNO3 and heat on the hot plate, with the sulfur when BaSO4 is present. When this test method is used
29.3.6 Paraffın. in diameter in the bottom of the ion exchange column, which
cover removed, until all bromine is expelled. Continue the for determination of combined plus inorganic sulfur, it must
29.3.7 Sodium Stearate Suspension in Water (1 g/dm3). is suspended upright by a clamp, and pour 5 g of ion exchange
determination as described in X1.3.3 – X1.3.5.
29.3.8 Sodium Sulfite Solution (50 g Na2SO3/dm3). resin in the acid form into the tube. Place a 250-cm3 beaker also be used for determination of inorganic sulfur (Section 33).
29.3.9 Starch Solution (10 g/dm3). 31. Sulfur in Rubber Products by Oxygen Flask under the outlet of the tube. Total sulfur shall be determined on an unextracted specimen;
29.3.10 Strontium Chloride Solution (5 g SrCl2/dm3). Combustion 31.7.11.2 Pour the contents of the flask into the ion ex- combined plus inorganic sulfur on an extracted specimen. This
change column, allowing it to trickle through at the rate of 2 to test method is applicable to NR, SBR, BR, IR, and CR
29.4 Procedure: 31.1 Scope: 3 drops per second into the beaker (mild pressure or vacuum products, and to the determination of total sulfur on NBR
29.4.1 Place 2 g of a sample thinly sheeted (0.5 to 0.75 mm 31.1.1 This test method covers the determination of all the being applied if necessary to achieve this rate). products.
(0.02 to 0.03 in.)) in a 400-cm3, thin-walled, chemically sulfur except that contained in barium sulfate, in a sample of a 31.7.11.3 If cations are not present, pour the contents of the
resistant glass9 flask. Add 100 cm3 of Na2SO3 solution, 5 cm3 rubber product. The test method is applicable to NR, CR, SBR, 32.2 Reagents:
flask into a 250-cm3 beaker, wash the flask, stopper hook and 32.2.1 Nitric Acid-Bromine Solution—Add a considerable
of a sodium stearate suspension in water, and approximately BR, IR, IIR, EPDM, and NBR products. platinum carrier three times with 5 cm3 of water, pouring the
1 g of paraffin. Cover the flask with a small watch glass and 31.1.2 This test method gives unreliable (usually low) excess of bromine to HNO3 so that a layer of bromine is
washings into the beaker, and proceed to 31.7.13. present in the reagent bottle. Shake thoroughly and allow to
gently boil for 4 h, or digest just below the boiling point for results in the presence of lead compounds. Antimony and 31.7.12 Wash the sides of the flask, stopper hook and
16 h. Remove the flask and add 100 cm3 of SrCl2 solution and barium salts interfere. stand 24 h before using.
platinum carrier three times with 5 cm3 of water from a wash 32.2.2 Sodium Carbonate (Na2CO3).
10 cm3 of cadmium acetate solution. Separate the rubber and 31.2 Summary of Test Method—The sample, wrapped in bottle, pouring the washings through the ion exchange column
filter paper, is burned in an oxygen combustion flask; the to be collected in the beaker. Then force out the last of the
9
Borosilicate glass, quartz glass, or similarly resistant material is satisfactory for carbon and hydrogen of the organic matter are oxidized, and liquid from the column by the application of mild vacuum or 19
Supporting data have been filed at ASTM International Headquarters and may
this purpose. the sulfur is converted to sulfate ions by combustion and pressure. be obtained by requesting Research Report RR:D11-1000.

13 15
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 D297 − 15 (2019) D297 − 15 (2019)
TABLE 4 Laboratory Quality Control Precision shall be determined by placing the calibrated thermocouple-sensing and test for the presence of lead with Na2CrO4 solution. that unvulcanized rubbers shall not be extracted with chloro-
Within Among element at approximately the geometric center of the furnace cavity. The Neutralize the last washing with NH4OH and test for the form (Note 8). Dry the extracted rubber in air or in an oven at
Mean, Laboratories Laboratories temperature shall be adjusted to be within the specific range. No more than
Sample
% two crucibles shall be placed in the oven and they shall be positioned
presence of lead with Na2CrO4 solution. If lead is present, 70°C.
S CV S CV continue to wash with hot HCl and finally, wash with warm
directly below the thermocouple. NOTE 8—Unvulcanized carbon black masterbatches containing no
1 3.79 0.0456 0.0133 0.1506 0.0431 HCl (1 + 7). Remove the crucible from the funnel, taking care
2 3.65 0.0673 0.0191 0.1211 0.0332 35.4.3 Remove the crucible from the furnace, cool in a added oils or plasticizers need not be extracted.
3 3.88 0.0906 0.0226 0.2592 0.0668 that the outside is perfectly clean, dry it in an air bath for 11⁄2 NOTE 9—Unvulcanized rubber compounds must be removed from the
desiccator, and weigh. filter paper and placed in the combustion boat before drying.
4 48.78 0.0457 0.0009 0.0797 0.0016 h at 110°C, cool, and weigh; this is mass a. Burn off the carbon
5 49.60 0.0924 0.0019 0.1963 0.0040 35.5 Calculations—Calculate the percentage of ash as fol- at a dull red heat (550 to 600°C) and reweigh; this is mass b. 39.5.2 Place the dried specimen in a silica boat and then
6 33.77 0.1488 0.0044 0.2809 0.0083
Reproducibility Repeatability
lows: The difference in mass represents approximately 105 % of the place the boat in the cool entrance of the combustion tube.
Standard deviation (S) 0.0914 0.2068 Ash, % 5 @ ~ A 2 B ! /C # 3 100 (25) carbon originally present in the form of carbon black. Close the entrance with the entry fitting. Connect the supply of
Coefficient of variation (CV) 0.0134 0.0363
38.5 Calculation—Calculate the percentage of carbon black oxygen-free nitrogen through a flow-meter to the entry fitting.
Least significant difference 0.258 0.5849 where:
(LSD) as follows: Pass nitrogen through the system at about 200 cm3/min for 5
A = grams of ash plus crucible, min. Then reduce the flow to 100 cm3/min and move the boat
B = grams of crucible, and Carbon black, % 5 @ ~ a 2 b ! / ~ 1.05 3 c ! # 3 100 (28) slowly into the hottest zone of the furnace over a period of 5
C = grams of specimen. min. Leave the boat in the hot zone for 5 min more. At the end
analysis of the inorganic fillers is required, it shall be made in where:
accordance with Sections 41 – 51. 35.6 Precision:20 c = grams of specimen used. of this period withdraw the boat to the cool end of the tube (or
35.6.1 These precision statements have been prepared in push it to the cool exit end) and allow it to cool for 10 min,
35. Fillers, Referee Ash Test Method accordance with Practice D3040. Please refer to this practice maintaining the flow of nitrogen. Remove the boat from the
39. Carbon Black, Method B, Pyrolysis Test Method
35.1 Scope: for terminology and other testing and statistical concept tube and cool it in a desiccator. Weigh to the nearest 0.1 mg.
35.1.1 This test method is intended for settling disagree- explanations. 39.1 Scope—This test method covers the determination of 39.5.3 Place the boat in a muffle furnace (or in a tube
ments on fillers content by the ashing method. It is also useful 35.6.2 The laboratory quality control precision of this test carbon black in a rubber product, vulcanized or unvulcanized, furnace with an air supply) at 800 to 900°C until all traces of
for ashing rubber products for determination of inorganic method was determined from an interlaboratory study of six by a pyrolysis method. The method is applicable to all “R” and carbon are burned off. Cool in a desiccator and weigh to the
sulfur in the absence of antimony (Section 33) or for ash different samples by five laboratories on two days. “M” family rubbers except those containing halogens or nearest 0.1 mg.
analysis (Section 41). 35.6.3 A test result is a single determination. nitrogen in the rubber polymer, or lead salts or phenolic resins
NOTE 10—The pyrolysis should be carried out in a fume hood. If this
35.1.2 This test method is not accurate for rubbers contain- 35.6.4 The least significant difference is expressed in abso- as added components. Application to other rubbers may be is not possible, lead the vapors from the exit end of the tube into an
ing halogens when zinc compounds or other metal compounds lute terms as percentage points and is based on 95 % confi- possible if no carbonaceous residue is formed under the exhaust hood or into a condensing trap. Xylene or other hydrocarbon
that form volatile halides are present and shall not be used if an dence limits. See Table 4. pyrolysis conditions. The method shall be used on such other solvents may also be used to trap the pyrolysis products.
analysis of these metals in the ash is required. polymers only if adequate testing of known compounds has 39.6 Calculation—Calculate the carbon black content of the
36. Fillers, Alternative Dry Ash Test Method demonstrated the usefulness of the test method. specimen as follows:
35.1.3 This test method may be used for preparing samples
for ash analysis on rubber products not containing halogens or 36.1 Scope—This test method is intended for use when a 39.2 Summary of Test Method—A weighed specimen of the Carbon black, % 5 @ ~ A 2 B ! /C # 3 100 (29)
antimony sulfide. However, if the sample contains carbonates muffle furnace is not available for ashing a rubber product rubber is extracted, placed in a combustion boat, and pyrolyzed
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that decompose at 550°C or clays or silicates that will lose sample. It is not considered to be as accurate or precise as the where:
at 800 to 900°C in a stream of nitrogen. The combustion boat
water at this temperature, the ash content value will not be muffle furnace method (Section 35) for fillers content because containing the nonvolatile residue is cooled and weighed. The A = grams of combustion boat and residue after pyrolysis
highly precise and will not represent the original amount of of lack of temperature control. It may be used, subject to the carbon black is then burned off in an air atmosphere and the in nitrogen,
inorganic fillers present in the sample. limitations stated in 35.1, for obtaining an ash for analysis. boat and contents are weighed again. The loss in mass B = grams of combustion boat and residue after ignition in
36.2 Summary of Test Method—A weighed sample is ashed represents carbon black. air, and
35.2 Summary of Test Method—A specimen is placed in a C = grams of specimen.
crucible and ashed in a muffle furnace at 550 6 25°C. The in a weighed crucible with a gas burner, slowly to char it, and 39.3 Reagents:
mass of residue in the crucible represents the ash content. finally with sufficient heat to burn off all carbonaceous matter. 40. Nitrogen Calculated as Glue
39.3.1 Nitrogen, dry and free from oxygen.
The residue in the crucible represents the ash content. 40.1 Scope—This test method is intended for use in the
35.3 Apparatus: 39.3.2 Acetone.
35.3.1 Crucible, porcelain or silica, approximately 50-cm3 36.3 Apparatus: 39.3.3 Chloroform. determination of glue when it is used as a filler in rubber
capacity. 36.3.1 Crucible, porcelain or silica, 30-cm3 nominal capac- products other than NBR products. This test method may also
35.3.2 Electric Muffle Furnace, with controls necessary to ity. 39.4 Apparatus: be used to determine nitrogen from NBR polymer present in a
hold the temperature at 550 6 25°C. 36.3.2 Clay Triangle. 39.4.1 Combustion Boat, silica. product (see 55.1). The calculations in this section are designed
35.3.3 Calibrated Thermocouple and Temperature Readout 36.4 Procedure—Weigh a 1-g specimen into an ignited 39.4.2 Electrically Heated Tube Furnace, capable of being for determination of glue in NR products. In the absence of
Device. weighed crucible. Place the crucible in a clay triangle and heat heated to 800 to 900°C. A means of advancing and withdraw- other nitrogenous material the method may be applied to
with a small flame until volatile pyrolysis products have been ing the combustion boat without allowing oxygen to enter the synthetic rubber products without correction for the nitrogen
35.4 Procedure:
driven off and the specimen is well charred. Increase the flame tube. content of the rubber polymer. A slight error will result from
35.4.1 Weigh a 1-g specimen of the sample into an ignited,
gradually to burn off carbonaceous material. The specimen 39.4.3 Flowmeter, calibrated at 100 and 200 cm3 of nitrogen content of antioxidants and accelerators present after
weighed crucible.
must not be allowed to catch fire at any time. Specimens that nitrogen/min. extraction. When glue is found to be present in a NR product
35.4.2 Adjust the temperature of the muffle furnace to 550
catch fire must be discarded. Heat until all carbonaceous 39.4.4 Muffle Furnace that can be maintained at 800 to (see 10.1.6) and determined by this method by calculation from
6 25°C, place the crucible in the furnace, and close the door
material is burned off. Cool the crucible in a desiccator and 900°C. nitrogen content, a correction shall be made for the natural
completely. When more than one crucible is to be placed in the
weigh. 39.4.5 Extraction Apparatus—See 19.2. protein in NR as shown in the calculations (see 40.4.2). The
furnace, the crucibles shall be placed on a tray and put into the
correction shall be made by the method of approximation. The
furnace at one time. The door must be closed immediately and 36.5 Calculations—Calculate the percentage of ash as fol- 39.5 Procedure: rubber as compounded (see 13.1) is calculated on the basis of
not opened for 1 h. After 1 h, open the furnace door 3 to 5 cm lows: 39.5.1 Weigh about 0.2 g of the sample to the nearest 0.1 the total nitrogen as glue. The glue content is then corrected on
and continue heating for 30 min or until all carbonaceous
mg. Wrap it in filter paper and extract in accordance with 19.4 the assumption that the rubber as compounded contains 0.4 %
material is burned off. 20
Supporting data have been filed at ASTM International Headquarters and may for 4 h with acetone. If bitumens or other materials insoluble in protein nitrogen and this value is used to calculate a more exact
NOTE 7—If a referee ash determination is required, the temperature be obtained by requesting Research Report RR:D11-1016. acetone are present, extract 4 h with chloroform (20.4) except figure for rubber hydrocarbon.

17 19
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are carefully controlled. Neutralize the filtrate from the deter- H2SO4 (1 + 5) reducing the iron with amalgamated zinc, and 47.4.6 EDTA Solution (0.01 M)—Dissolve 3.72 g of ethyl- EDTA solution to a yellow-green color, using the buret selected
mination
3
of SiO2 and insoluble matter with NH4OH, and add titrating the iron with KMnO4 solution, 45.1.9. ene diamine tetraacetic acid, disodium salt, dihydrate, in water from the table in 47.5.3.
1 cm of HCl. Run a rapid stream of H2S into the solution and and dilute to 1 dm3. 47.5.5 Lead Present—Dilute the aliquot to 25 cm3. Add
dilute to between 50 and 100 cm3. Continue the addition of 45. Calcium Oxide 47.4.7 Standardization—With a pipet, transfer 25 cm3 of 2 cm3 of AlCl3 solution, 10 cm3 of NH4F solution, and a drop
H2S until precipitation is complete. Filter, and wash with a 45.1 Reagents: standard zinc chloride solution to a 250-cm3 conical flask. Add of methyl orange indicator solution. Add NH4OH until the
saturated solution of H2S. Save the filtrate for determination of 5 cm3 of HCl and proceed according to 47.5.4, beginning with indicator turns orange-yellow, add 1.0 cm3 of HCl, and bring
45.1.1 Ammonium Oxalate, Saturated Solution.
iron and aluminum oxides in Section 44. If antimony is present, the addition of AlCl3 solution. Use the 50-cm3 buret for the solution to a boil. Cool the solution. Add NH4OH until the
45.1.2 Ammonium Sulfate ((NH4)2S).
it will precipitate under these conditions; zinc may also be titration. indicator turns yellow and proceed as in 47.5.4, cooling the
45.1.3 Formic Acid Mixture—Mix together 200 cm3 of
precipitated, but neither will interfere with the determination of 47.4.8 Methyl Orange Solution (1 g/dm3)—Dissolve 0.025 g solution in an ice bath before titration. Titrate the cold solution.
formic3 acid (HCOOH, density 1.22), 770 cm3 of water, and
lead. Dissolve the PbS in HNO3 (1 + 1); boil to complete of methyl orange in 25 cm3 of water. 47.6 Calculations:
30 cm of NH4OH. (Warning—Unopened bottles of formic
solution. If antimony is present it may not be dissolved by this 47.6.1 Standardization:
acid may have sufficient pressure to cause an explosion as the 47.4.9 2,4-Pentanedione Solution—Dissolve 10 cm3 of 2,4-
procedure. Filter. Cool the filtrate, add 10 cm3 of H2SO4, and
top is removed. Protective clothing and shielding should be pentanedione in 90 cm3 of acetone. C 5 W/ ~ V 3 40! (39)
evaporate to dense white fumes of H2SO4. Cool, dilute with
3 used when a bottle is first opened. Do not allow formic acid to 47.4.10 Zinc Chloride, Standard Solution—Ignite zinc ox-
50 cm of water, add an equal volume of ethanol (95 percent), 47.6.2 Analysis:
come in contact with the skin.) ide in a porcelain crucible for 2 h at 550°C and cool in a
and let stand overnight. Filter through a tared Gooch crucible,
wash with ethanol (50 %), and dry at 105°C. 45.1.4 Formic Acid Wash Solution—Dilute 30 cm3 of formic desiccator. Dissolve about 1.0 g of the dried reagent, weighed ZnO, % 5 ~ V 3 C 3 100 3 100! / ~ S 3 A ! (40)
acid mixture (44.1.3) to 1 dm3 and saturate with H2S. to the nearest 0.001 g, in 50 cm3 of water and 20 cm3 of HCl. where:
43.3 Calculation—Calculate the percentage of lead oxide as 45.1.5 Hydrogen Sulfide (H2S). Transfer to a 1000-cm3 volumetric flask and dilute to the mark
follows: C = concentration of EDTA solution, g ZnO/cm3,
45.1.6 Methyl Red Indicator Solution. with water.
W = grams of zinc oxide,
Lead oxide, % 5 ~ A 2 B ! 3 0.736/C 3 100 (34) 45.1.7 Oxalic Acid Solution (100 g/dm3). 47.4.11 Magnesium Chloride Solution (0.1 M)—Dissolve V = volume of EDTA solution used in titration, cm3,
where: 45.1.8 Oxalate Wash Solution, containing 2 g of ammonium 2.03 g of magnesium chloride hexahydrate (MgCl2·6H2O) in S = grams of sample, and
oxalate and 1 g of oxalic acid/dm3. water and dilute to the 100 cm3 mark with water. A = aliquot size, cm3.
A = mass of crucible and PbSO4,
45.1.9 Potassium Permanganate, Standard Solution (0.1 47.7 Precision: 21
B = mass of crucible, 47.5 Procedure:
C = mass of original specimen, and N)—Dissolve approximately 3.2 g of potassium permanganate 47.7.1 These precision data are based on tests of 6 samples
(KMnO4) in 1 dm3 of water. Age the solution at least 48 h and 47.5.1 Weigh approximately 1 g of sample to the nearest
0.736 = conversion factor from PbSO4 to PbO. 0.001 g in a 50-cm3 porcelain crucible. If the sample does not by 7 laboratories on two days. The range of samples studied
filter through a filter crucible (45.2.1). Standardize within 24 h was from about 1 to 27 % ZnO. Precision is expressed in
of use, against the National Institute of Standards and Tech- contain CR or other rubbers containing halogens, ash it in
44. Iron and Aluminum Oxides (R2O3) accordance with 35.4.2 or 36.4. If halogens are present, ash the relative terms (2S %, D2S %).
nology standard sample No. 40 of sodium oxalate in accor- 47.7.2 Repeatability (Single-Operator)—The repeatability
44.1 Reagents: dance with the instructions furnished with the standard sample. sample in accordance with Section 37.
44.1.1 Ammonium Chloride (NH4Cl), solid. 47.5.2 Cool the crucible and wash the ash into a 250-cm3 has been estimated to be 63.0 % (2S %) of a determination.
45.2 Apparatus: beaker with a stream of water. Add 5 cm3 of HCl to the crucible Two test results should be considered acceptable if their
44.1.2 Ammonium Chloride Solution (20 g NH4Cl/dm3).
45.2.1 Filter Crucibles, filter crucibles that will withstand and warm it on a hot plate until the solution just begins to boil. difference does not exceed 4.2 % (D2S %) of their average
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44.1.3 Methyl Red Indicator Solution.

the firing temperature required in the specific application. Pour the washings into the beaker. Rinse the crucible once value.
44.1.4 Potassium Ferricyanide Indicator (K3Fe(CN)6).
more with 5 cm3 of HCl and again add the washings to the 47.7.3 Reproducibility (Multilaboratory)—The reproduc-
44.1.5 Potassium Pyrosulfate (K2S2O7). 45.3 Procedure:
beaker. Do not filter the solution. Then add 10 cm3 of HCl to ibility has been estimated to be 64.4 % (2S %) of a determi-
45.3.1 If acid-soluble barium salts were found to be absent
44.2 Procedure—Boil the filtrate from the lead sulfide nation. Two test results should be considered acceptable if their
(10.1.4), dilute the filtrate from the R2O3 determination to the beaker. Break up any large cakes of ash with a glass stirring
precipitation (see 43.2) to expel H2S. Adjust the volume of difference does not exceed 6.2 % (D2S %) of their average.
200 cm3, add methyl red indicator, and neutralize with H2SO4 rod. Evaporate the solution to 10 cm3. If large amounts of
solution to 100 to 150 cm3. Add a few drops of HNO3 and boil
(1 + 36). Add 25 cm3 of formic acid mixture. precipitate are present some bumping and splattering may 48. Total Barium as Barium Sulfate
the solution again. Test for ferrous iron, using K3Fe(CN)6 as an
45.3.2 If acid-soluble barium salts were found to be present, occur. This can be reduced by agitating the solution until
outside indicator on a spot plate. If ferrous iron is present, add 48.1 Reagents:
remove the barium as follows: Dilute the filtrate from the R2O3 boiling begins. Transfer the solution to a 100-cm3 volumetric
more HNO3 and proceed as before until all the iron is oxidized. 48.1.1 Hydrogen Sulfide (H2S).
determination to 200 cm3, neutralize with HCl (1 + 1) and add flask and dilute to the mark with water.
Add 5 g of solid NH4Cl. Add NH4OH until the solution is 48.1.2 Sodium Carbonate (Na2CO3), solid.
colored definitely yellow by methyl red, but do not add an 10 cm3 in excess. Heat to boiling. Add H2SO4 (1 + 36) to 47.5.3 Select an aliquot from the following table and
48.1.3 Sodium Carbonate Solution (50 g Na2CO3/dm3).
excess. Heat to boiling and boil for 5 min. When the precipitate precipitate barium, but avoid a large excess. Digest until the transfer it to a 250-cm3 conical flask, mixing the solution and
48.1.4 Sodium Nitrate (NaNO3).
has settled, filter, with the aid of filter pulp if the precipitate is precipitate settles, test for completeness of precipitation, and suspended solids well before aliquoting. Proceed with 47.5.4 or
digest for at least 2 h or until the precipitate is filterable. Filter, 47.5.5. 48.2 Procedure—Analyze a specimen of ash (35.4.2 or
large, and wash with NH4Cl solution. Save the filtrate for
wash, and discard the precipitate. Concentrate the filtrate to ZnO Expected, % Aliquot Size, cm3 Buret Size, cm3
36.4) that has been ashed in a 50-cm3 crucible, for total barium
determination of calcium oxide in Section 45. Carefully char
200 cm3, neutralize with NH4OH using methyl red indicator, as follows: Fuse the specimen with 5 g of a mixture of equal
off the filter paper at a low temperature and ignite the residue 0 to 3 25 10
neutralize with H2SO4 (1 + 36) and add 25 cm3 of formic acid 3 to 8 10 10 parts of Na2CO3 and NaNO3. Stir well during the fusion. Cool
in a freely oxidizing atmosphere.
mixture. >8 10 50 the crucible, place it in a 400-cm3 beaker with about 125 cm3
44.3 Calculation—Calculate the percentage of R2O3 as 45.3.3 Proceed at this point to remove zinc from the 47.5.4 Lead Absent—Dilute the aliquot to 25 cm3 and add of water, and digest on the steam plate or steam bath overnight.
follows: solutions from 45.3.1 or 45.3.2 by heating the solution to 60°C 1 cm3 of concentrated HCl, 2 cm3 of AlCl3 solution, 5 cm3 of Filter the solution and wash the residue well with hot Na2CO3
R 2 O 3 , % 5 @ ~ A 2 B ! /C # 3 100 (35) and saturating with H2S for 20 min. Digest for 1 h at 60°C, MgCl2 solution, 10 cm3 of NH4F solution, and 1 drop of solution. Wash this residue back into the original beaker with
filter, and wash with formic acid wash solution. Test for methyl orange indicator solution. Add NH4OH until the indi- hot water, dissolve the residue in the beaker and any traces on
where: the filter paper with HCl, and heat the solution on the steam
complete removal of zinc with (NH4)2S in alkaline solution. cator is pure yellow in color and add 0.5 cm3 more NH4OH. If
A = mass of crucible and R2O3(Fe2O3 + Al2O3), Filter again if necessary. Make the filtrate just acid with HCl the sample is known to be high in zinc or calcium, bring it to bath. Filter and wash thoroughly with hot water. Adjust the
B = mass of crucible, and (1 + 1) and evaporate to 150 cm3. Filter to remove sulfur. Add a boil, boil 30 s, and cool to room temperature. Add 10 cm3 of acidity by means of NH4OH (2 + 3) and HCl (1 + 1) to provide
C = mass of original specimen. methyl red indicator, heat to 50°C, neutralize with NH4OH, buffer solution, 60 cm3 of acetone and 5 drops of dithizone
44.4 Iron in the R2O3 residue may be determined, if desired, and add 1 cm3 in excess. Make the solution just acid with indicator solution. If the iron content is equal to or higher than 21
Supporting data have been filed at ASTM International Headquarters and may
by fusing the residue with K2S2O7, dissolving the melt in oxalic acid solution, add 12 cm3 in excess, and boil for 2 min, that of zinc, add 5 cm3 of 2,4-pentandione solution. Titrate with be obtained by requesting Research Report RR:D11-1009.

21 23
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 D297 − 15 (2019) D297 − 15 (2019)
to 200 cm3, regulate the temperature to about 60°C, add 2 (6 + 100). Cool the solution and transfer to a 250-cm3 volu- TABLE 6 Behavior of Rubber-Like Materials in Chronic If unreacted specimen is present after 1 h of digestion, repeat the
drops of 0.2 % methyl red solution, and titrate with 0.1 N metric flask, rinsing with H2SO4 (6 + 100). Dilute to volume Acid Oxidation Procedure determination.
KBrO3 solution until the solution is colorless. with water and mix well. Carry a blank through the same Material Value Obtained 53.2.3.3 Place 700 to 900 cm3 of water in the steam-
Hard NR or IR products approximately 50 % of its mass reacts as if
50.2.4 When the indicator starts to fade, add the KBrO3 procedure. it were isoprene polymer generating flask, A (of Fig. 4). Place a few cubic centimetres of
slowly, using another drop of indicator if desired. At the end 51.4.2 If a spectrophotometer with 1-cm cells is used for NR (Balata) approximately equivalent to isoprene water, sufficient to cover the end of the adapter, in the receiving
point, an added drop of indicator should become colorless. If absorbance measurement, proceed as in 51.4.2.1 and 51.4.2.2. polymer flask, H. Mark the outside of the digestion flask, C, at a point
TR approximately 18 % of its mass reacts as if
iron is found to be absent, it is not necessary to precipitate the If a filter photometer is used for this measurement, proceed as it were isoprene polymer indicating the liquid level when the flask contains 75 cm3.
antimony with H2S and the second heating in the Kjeldahl flask in 51.4.2.3. NBR approximately 1.5 to 2 % of its mass reacts Transfer 50 6 1 cm3 of the chromic acid digestion mixture in
may be eliminated. 51.4.2.1 Transfer a 15-cm3 aliquot of the standard titanium as if it were isoprene polymer the digestion flask. Lift the steam tube, B, and insert the
SBR approximately 3 % of its mass reacts as if
50.3 Calculation—Calculate the percentage of antimony as solution to a 50-cm3 volumetric flask, add 2 cm3 of H3PO4 and it were isoprene polymer specimen extracted in accordance with 53.2.3.1 or 53.2.3.2 into
antimony sulfide (Sb2S3), as follows: 5 cm3 of H2O2 (3 %) to the flask, and dilute to volume with CR approximately 3 % of its mass reacts as if the digestion flask (Note 14). Replace the steam tube and
it were isoprene polymer if a modification tighten the connection. Heat the beaker of water surrounding
H2SO4 (6 + 100). Allow to stand 5 min and measure the of the procedure is used to avoid the
Antimony as Sb2 S 3 % 5 @ ~ A 3 N 3 0.0849! /B # 3 100 (46) the digestion flask to boiling, continue boiling for 1 h, and
absorbance in 1-cm cells at 416 nm, using H2SO4 (6 + 100) in interference of chlorineA
where: the reference cell. Prepare the blank and measure its absor- IIR virtually unattacked but interferes by remove the burner and beaker.
preventing complete reaction with NR or
A = volume of KBrO3 solution required for titration of the bance in the same manner. IR. NOTE 14—It is not necessary to remove the filter paper quantitatively
specimen, cm3, 51.4.2.2 Calculate the absorptivity of TiO2 as follows: A from the sample before transferring it to the digestion flask, since the
This modification consists of adding neutral KI solution to the distillate after
N = normality of the KBrO3 solution, and TiO2 absorptivity, a, 5 @ ~ A A 2 A B ! 3 50# /CD (47) aeration and titrating any iodine that may be released with neutral Na2S2O3 interference of small amounts of cellulose is negligible.
B = grams of specimen used. solution before proceeding with the titration with 0.1000 N NaOH solution.
53.2.3.4 During the digestion period, heat the steam-
where:
The percentage of Sb2S3 will not usually represent the exact generating flask, A, with the stopper removed, until the
weight of the substance as compounded since commercial AA = absorbance of the diluted aliquot containing titanium, contents are boiling. At the end of the digestion period, replace
antimony sulfide normally has some excess sulfur or other AB = absorbance of diluted blank aliquot, the stopper and outlet tube in the mouth of the steam-
impurities present. C = volume of aliquot taken, cm3 and 53.2.2.1 Alcoholic Phenolphthalein Indicator Solution (10 generating flask, adjust the burner to maximum heat, and pass
D = milligrams of TiO2 per cubic centimeter of original g/dm3)—Dissolve 10 g of phenolphthalein in 500 cm3 of the steam through the digestion flask, C. When the volume of
51. Titanium Dioxide22 solution. ethanol, and dilute to 1 dm3. the liquid in the digestion flask is increased to approximately
51.1 Scope—This test method covers the determination of 51.4.2.3 Obtain data for a calibration curve by diluting 53.2.2.2 Chromic Acid Digestion Mixture—Dissolve 200 g 75 cm3, place a small flame under the flask, keeping it at a
titanium dioxide (TiO2) in any rubber product. It may also be aliquots of the TiO2 solution and of the blank to 50 cm3 with of chromic oxide (CrO3) in 500 cm3 of water, add 150 cm4 of point that will maintain the volume in the digestion flask at
used qualitatively to detect the presence of TiO2 in the ash of H2SO4 (6 + 100), after the addition of 2 cm3 of H3PO4 and H2SO4, and mix well. 75 cm3. Continue the distillation until 500 cm3 have been
a rubber product. This test method is based on fusion of the 5 cm3 of H2O2 (3 %) and measuring the absorbance against 53.2.2.3 Sodium Hydroxide, Standard Solution (0.1 M)— collected in the receiving flask, H. Remove the burners,
rubber product ash with potassium pyrosulfate, dissolution of H2SO4 (6 + 100) in a filter photometer using a filter having a Prepare and standardize a 0.1 M sodium hydroxide (NaOH) immediately remove the receiving flask and the adapter, G, and
the fused mixture in dilute H2SO4, and the formation of a maximum transmittance at or near 416 nm. From these data solution. rinse the adapter with water from a wash bottle, catching the
colored titanium complex with hydrogen peroxide. construct a calibration curve of milligrams of TiO2 per cubic 53.2.3 Procedure: washings in the receiving flask.
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centimetre of solution against absorbance of the solution minus 53.2.3.1 Vulcanized Rubber Products—Weigh a sufficient 53.2.3.5 Adjust the temperature of the liquid in the receiv-
51.2 Reagents: amount of the sample, sheeted to a thickness of 0.5 mm (Note
absorbance of the blank diluted in the same manner. Use only ing flask to 25 6 5°C. Attach J to H as in aeration assembly I
51.2.1 Hydrogen Peroxide (3 %)(H2O2). 12) to contain approximately 0.3 g of isoprene polymer. Wrap
absorbance values between 0.15 and 1.5. of Fig. 4, and attach to a vacuum line. Draw a stream of air
51.2.2 Phosphoric Acid (H3PO4). the specimen loosely in filter paper and extract by the total
51.2.3 Potassium Pyrosulfate (K2S2O7), powder. 51.5 Procedure: through the liquid for 30 min at a rate of approximately
extract procedure as described in Section 20, or extract 2 dm3/min. Remove the rubber tubing and loosen the two-hole
51.2.4 Titanium Dioxide (TiO2). 51.5.1 Accurately weigh a 50 to 60-mg specimen of rubber
unwrapped specimens each weighing about 0.1 g with methyl stopper. Rinse the stopper and glass tubing with water from a
product into a 3 to 4-cm3 platinum crucible. If the approximate
51.3 Apparatus: ethyl ketone by the rapid reflux procedure (see 26.3). After wash bottle, catching the rinsings in the receiving flask. Add
TiO2 content is known, adjust the specimen size to assure an
51.3.1 Photoelectric Photometer—A spectrophotometer or extraction, dry the specimen in an oven at 100°C for 1 h. alcoholic phenolphthalein indicator solution to the receiving
absorbance reading between 0.15 and 1.3. Place crucible and
filter photometer suitable for measurement of absorbance at flask, and titrate with 0.1 M NaOH solution. (Warning—The
specimen in a cold muffle furnace and heat to 550° C, NOTE 12—The sample must be sheeted to a thickness of 0.5 mm or less,
approximately 416 nm, with matched absorption cells 1 to since some materials, such as unvulcanized NR or IR, may not otherwise rates of loss of carbon dioxide and of acetic acid during
continuing heating until no carbonaceous material remains.
3 cm in thickness. be completely attacked by the oxidation mixture. aeration have been investigated for the temperature range, type
Remove the crucible from the furnace, cool, add 1.3 to 2.0 g of
51.4 Calibration of Photoelectric Photometer: fused K2S2O7 powder and 2 to 3 drops of H2SO4 to the ashed 53.2.3.2 Unvulcanized or Reclaimed Rubber Products— of apparatus, and rate of air flow recommended. Variation of
51.4.1 Accurately weigh 0.125 g of TiO2 into a 30-cm3 specimen and to a blank crucible. Heat gently until the Weigh a sufficient amount of the specimen, sheeted to a any of these factors may lead to erroneous analytical results.)
platinum crucible. Add 6 g of fused K2S2O7 powder and 2 to 3 pyrosulfate is melted. Gradually increase the heat until the thickness of 0.5 mm (Note 12), to contain approximately 0.2 g 53.2.3.6 Blank—Make a blank determination, following the
drops of H2SO4. Heat the crucible gently until all the pyrosul- bottom of the crucible is dull red and continue heating for 10 of isoprene polymer. If the material is suspected of containing procedure described in 53.2.3.3 – 53.2.3.5, using the same
fate is melted. Gradually increase the heat until the bottom of to 15 min. Any residue at this point is silica or clay. Cool the mineral rubber or factice, vulcanize the material by a simple amounts of all reagents. The blank should not exceed 0.2 to
the crucible is a dull red and continue heating until the TiO2 is crucible while carefully rolling the melt around the inside of recipe and extract a specimen of the vulcanizate by the total 0.3 cm3.
completely dissolved. Allow to cool while carefully rolling the the crucible. extract procedure (Section 21) or by the rapid reflux procedure 53.2.4 Calculation—Calculate the percentage of isoprene
melt around the walls of the crucible to facilitate dissolution of 51.5.2 Place crucible and contents in a 50-cm3 beaker and with methyl ethyl ketone (26.3) (Note 13). Dry in an oven at polymer as follows (Note 15):
the fused material. Place the crucible and contents in a 150-cm3 cover with H2SO4 (6 + 100). Cover the beaker with a watch 100°C for 1 h. Isoprene polymer, % 5 9.08 ~ A 2 B ! M/C (50)
beaker containing 50 cm3 of water. Carefully add, with stirring, glass and boil the mixture slowly until dissolution is complete NOTE 13—Poorly vulcanized rubber product must not be extracted with where:
25 cm3 of H2SO4. Cover the beaker and boil gently until except for clay or silica. Remove the heat and remove the chloroform. Unvulcanized crude rubber or crude rubber products shall be
dissolution is complete. Remove the heat and remove the crucible from the beaker with a glass rod, washing with H2SO4 extracted with acetone as described in 19.4 or 26.3. Unvulcanized rubber A = volume of NaOH solution required for titration of the
crucible from the beaker with a glass rod, washing with H2SO4 (6 + 100). Filter through paper or a filter crucible if the solution or rubber products shall be sheeted to the required thickness under specimen, cm3,
is not perfectly clear and quantitatively transfer the solution to
conditions that will not produce a sticky specimen resulting from B = volume of NaOH solution required for titration of the
excessive breakdown of the rubber polymer, preferably using mill rolls of blank, cm3,
22
The nomenclature and abbreviations used in this test method are in accordance a 50-cm3 volumetric flask, using H2SO4 (6 + 100) for rinsing equal or nearly equal speeds. Careful examination of the reaction mixture
M = molarity of NaOH solution, and
with Terminology E131. the beaker and filter. Add 2 cm3 of H3PO4 and 5 cm3 of H2O2 after digestion is necessary to detect the presence of unreacted specimen.

25 27
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D297 − 15 (2019) D297 − 15 (2019)

54.2 Summary of Test Method—The sample, wrapped in 54.5.1 The rubber must be milled finely on a laboratory roll finally with a 3-mm (0.125-in.) top layer of diatomaceous earth 56.5.3 Add 1 level teaspoon of filter aid, stir with a glass
filter paper, is burned in an oxygen combustion flask; the mill before weighing. filter aid from a suspension in acetone to a total depth of about rod, and filter hot through an aged prepared Büchner funnel A
carbon and hydrogen of the organic matter are oxidized and the 54.5.2 Due to the small sample size the rubber and filter 6 mm (0.25 in.). Remove the acetone with suction and age at into a 500-cm3 filtering flask containing 100 cm3 of water. Use
chlorine compounds are converted to chloride, which is titrated paper should be protected from contamination, and all opera- least 24 h before using (Note 16). low to moderate suction and a fume hood. Wash beaker and
with standard alcoholic silver nitrate solution. tions prior to combustion should be carried out with plastic 56.3.6 Büchner Funnel B—A No. 1 Büchner funnel lined filter twice with 20-cm3 portions of HNO3 at room temperature.
54.3 Apparatus: gloves. first with a circle of S & S No. 598 filter paper, then with Wash copiously with at least 300 cm3 of hot water until the
54.3.1 Oxygen Combustion Flask (Schöniger Flask)23—A medium-fiber asbestos to a depth of about 3 mm (0.125 in.) and filtrate is colorless. Discard the filtrate and rinse the flask with
54.6 Safety Precautions—The following safety precautions
chemical-resistant,7,10 thick-walled oxygen combustion flask, finally with a 3-mm (0.125-in.) top layer of diatomaceous earth water. (Warning—There is danger of a violent reaction be-
must be observed in the combustion of rubber samples:
1000 cm3, with 35/25 ball-joint stopper, platinum sample filter aid from a suspension in acetone to a total depth of about tween nitric acid and alcohol.) Attach the filter to the cleaned
54.6.1 The flask must contain no residues of organic sol-
carrier and pinch clasp. 6 mm (0.25 in.). Remove the acetone with suction. Wash with filter flask, wash with 50 cm3 of ethanol, and dry on the filter
vents or vapor, which could cause an explosion. Any such
54.3.2 Infrared Safety Igniter,7,11with cabinet and infrared the equal volume mixture of chloroform and 30 to 60°C with continued suction.
solvents used for cleaning the flask should be repeatedly rinsed
light (an electrical igniter is also satisfactory). petroleum ether. Remove the solvent mixture with suction. Age
out with water. 56.5.4 With the aid of a spoon or spatula, carefully transfer
54.3.3 Buret, 25-cm3 capacity, with 0.1-cm3 graduations. at least 24 h before using (Note 16).
54.6.2 The pressure generated by the rapid combustion the contents of the funnel to a dry 250-cm3 Erlenmeyer flask.
54.3.4 Magnetic Stirring Bar, covered with chemical- could cause the flask to explode. Hence, combustion must take NOTE 16—The preparation of the filter funnels as described has been Use filter paper wet with chloroform to clean the last traces
resistant coating,12 approximately 25 mm (1 in.) long, without place in the safety chamber with the door locked or behind a found to be important to the success of the method. The use of other
from the funnel. Add six to ten carborundum bumping stones,
spinning ring around the center. materials of equivalent properties in the preparation of the filters should be
safety shield or hood shield (preferably in a safety chamber tested with samples of known composition. 100 cm3 of chloroform, 100 cm3 of petroleum ether, and 5 to
54.3.5 Magnetic Stirrer. which is itself behind a shield); the hands and face must be 3

56.3.7 Diatomaceous Earth Filter Aid.7,29 7 cm of tert-butyl hydroperoxide. Connect the Hopkins con-
54.3.6 Filter Paper, 30 by 30-mm, with a 35-mm extension, withdrawn behind a screen before the flame reaches the sample
56.3.8 Filtering Fiber, medium. denser and reflux rapidly at least 4 h. Replace any appreciable
black7,14 for infrared or white7,15 for electrical ignition. itself. Goggles, or a face shield, must be worn during this
54.3.7 pH Meter,7,24 equipped with a billet-type silver amount of evaporated solvent with chloroform-petroleum ether
process. 56.4 Reagents:
electrode7,25 and a calomel7,25 electrode in which the potas- mixture (1 + 1).
54.6.3 The flask should be left in the safety chamber until 56.4.1 Acetone—See 19.3.
sium chloride has been replaced by a saturated potassium 56.4.2 Chloroform—See 20.3. 56.5.5 Filter the refluxed sample, warm, through an aged
the last spark is extinguished. At this point it is removed; but
nitrate solution, or equivalent automatic titrator. 56.4.3 Chloroform-Petroleum Ether Mixture (1 + 1). Mix prepared Büchner funnel B into a clean, dry 500-cm3 filtering
since a slight vacuum is formed, continue wearing goggles or
54.4 Reagents—To conserve reagents make only as much face shield. equal volumes of chloroform and petroleum ether. flask, using moderate suction. (Too much suction may cause
solution as needed for the required analyses, or that can be 56.4.4 Ethanol—Formula 2B denatured ethyl alcohol or some carbon black to pass through the filter and necessitate
54.7 Procedure: refiltering.) With a wash bottle, wash the flask and filter five
stored for future needs. absolute ethanol.
54.7.1 Place 10 cm3 of water, 2.0 cm3 of 2 M KOH solution, 56.4.5 Petroleum Ether, 30 to 60°C boiling range. times with 20-cm3 portions of warm chloroform-petroleum
54.4.1 Acidified Ethanolic Silver Nitrate Solution (0.01
the stirring magnet, and 3 drops (added by medicine dropper) 56.4.6 Tert-Butyl Hydroperoxide, commercial grade.7,30 ether mixture (1 + 1). Be sure to wash well the edge and side
M)—Pipet 100 cm3 of standard26 0.1 M silver nitrate solution
of 30 % hydrogen peroxide solution in the 1000-cm3 combus- 56.4.7 Xylene. wall of the funnel with the stream from the wash bottle.
into a 1-dm3 volumetric flask containing about 500 cm3 of
tion flask.
denatured ethanol (Formulas SD 3A, 1 or 2B, or 30), add 56.5 Procedure: 56.5.6 Add two No. 6 Carborundum bumping stones to a
3 54.7.2 Fold the filter paper into a U-shaped sample boat
clean 250-cm3 beaker. Evaporate portions of the filtrate from
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2.0 cm of nitric acid (1 + 1) and when this has cooled to room 56.5.1 Homogenize and sheet out the sample with a tight
according to Fig. 1 A and B of Test Method E442.
temperature dilute to volume with ethanol. Protect from the rubber mill to a thickness of 0.5 mm. Accurately weigh a 56.5.5 in the 250-cm3 beaker until all the filtrate has been
light. Titrate an accurately weighed sample of reagent grade 54.7.3 Weigh a sample of rubber of 30 to 60 mg, which
specimen of appropriate size to contain between 0.05 and reduced to a small volume. Wash the filter flask well with the
potassium chloride (KCl) or sodium chloride (NaCl) as in should not exceed about 0.5 milliequivalents of chlorine, to
0.20 g of polyisobutylene. Do not use more than 5 g. Use 1 g chloroform-petroleum ether mixture (1 + 1). Add these wash-
54.7.12 and calculate the molarity as follows: 0.1 mg. Place the rubber sample in the sample boat.
for unknown range and repeat with adjusted sample size if less ings to the beaker and evaporate to about 20 cm3. Transfer the
54.7.4 Fold the paper according to 8.2.4 and 8.2.5 of Test
Molarity 5 ~ A 3 1000! / ~ B 3 C ! (51) than 0.05 g or more than 0.20 g is found. Add to 200 cm3 of solution to an accurately weighed, clean, dry 50-cm3 Erlen-
Method E442. Place the folded paper firmly in the platinum
acetone in a 250-cm3 Erlenmeyer flask, connect to a reflux meyer flask containing two No. 6 Carborundum bumping
where: sample carrier hung on the hook of the stopper with the pointed
condenser, and reflux 1 h. Remove the sample, blot off acetone stones and wash the beaker well with the chloroform-
a = mass of chloride weighed, g, end of the paper projecting outward.
with a paper towel, and dry for 10 min in an oven at 105 to petroleum ether mixture (1 + 1). Carefully evaporate to about 1
b = molecular mass of chloride weighed, and 54.7.5 Insert a tube from the oxygen cylinder close to the
110°C. to 3 cm3 on a hot plate at 140°C. Do not evaporate to dryness.
c = titration volume, cm3. bottom of the flask as in Fig. 2 A of Test Method E442, and
56.5.2 Cut into 5 by 10-mm or smaller pieces and place in Allow the flask to cool to room temperature and then add 25
blow in oxygen strongly for at least 0.5 min.
54.4.2 Hydrogen Peroxide (30 %) (Warning—Thirty per- a 250-cm3 beaker. Add 10 cm3 of HNO3 and allow to stand at 3
cm ethanol. (If there is no precipitate or turbidity at this point
cent hydrogen peroxide is very corrosive to the skin; wear 54.7.6 Smoothly remove the oxygen tube and close the room temperature in a hood until initial frothing reaction
stopper without letting the platinum carrier drop into the liquid. polyisobutylene is not present and the analysis may be termi-
rubber or plastic gloves and goggles when handling it.) subsides. If the reaction is slow, warm the beaker on a hot plate nated.) Boil gently on a hot plate at 140°C for at least 15 min,
54.4.3 Nitric Acid (1 + 1)—Mix equal volumes of nitric acid 54.7.7 With the stopper upright, clamp the stopper tightly at 140°C until fuming just begins and then remove immedi-
with the pinch clamp. until the alcohol is clear and all the isobutylene coagulates and
(HNO3) (density, 1.40 Mg/m3) and water. ately. If there is no reaction after 5 min on a hot plate at 140°C, adheres to the flask. If turbidity persists, evaporate to about 2
54.4.4 Potassium Hydroxide (2M)—Dissolve 112 g of po- 54.7.8 Place the flask in the infrared igniter chamber with remove anyway. When all reaction stops and the beaker has
the pointed end of the paper in line with the infrared beam and to 3 cm3, cool to room temperature, and add 25 cm3 of acetone.
tassium hydroxide (KOH) pellets in water and dilute to 1 dm3. cooled to room temperature, add 50 cm3 of HNO3 and 10 cm3
approximately perpendicular to it. Close the door and turn on of xylene. Place on a hot plate at 140°C, cover with a watch 56.5.7 Cool to room temperature and carefully decant the
54.4.5 Oxygen, in compressed gas cylinder.
the infrared light (or electric igniter) until the paper ignites. glass, and digest 30 min. Remove the watch glass and digest at alcohol (or acetone). Wash the precipitated polyisobutylene by
54.5 Sample Preparation and Handling: swirling gently with 25 cm3 of acetone at room temperature
54.7.9 After the burning ends, stir the still-sealed flask least 30 min more until xylene is completely evaporated.
vigorously on a magnetic stirrer for 1 h. Alternatively, it may and decanting. Dry the flask and polyisobutylene 2 h in an oven
23
Borosilicate glass has been found satisfactory. at 105 to 110°C, cool in a desiccator, and weigh.
24
be allowed to stand undisturbed for 2 h. 29
The sole source of supply of the pH meter (Model SS-2) known to the The sole source of supply of the apparatus (Celite Analytical Filter Aid) known
committee at this time is A. H. Beckman. 54.7.10 Remove the pinch clamp, tilt the stopper to release to the committee at this time is Celite Corporation, 130 Castilian Dr. Goleta, CA 56.6 Calculations—Calculate the percentages of polyiso-
25
The sole source of supply of the apparatus (catalog No. 3-571) known to the the vacuum, and open the flask. 93117 .
butylene and IIR as follows:
30
committee at this time is Coleman. The sole source of supply of tert-butyl hydroperoxide known to the committee
26
54.7.11 Transfer the contents of the combustion flask (with
The 0.1 M silver nitrate solution should be prepared in accordance with at this time is Lucidol Division, Wallace and Tiernan Co., Inc., Buffalo, NY. This A 5 @ ~ B 2 C ! /D # 3 100 (55)
Practice E200. One to ten dilution of this reagent with denatured ethanol produces the exception of the platinum carrier) to a 250-cm3 beaker, material is said to be of 60 % minimum purity and stable for several months if stored
an approximate molarity of 0.01. which is shielded from light. Rinse the sample carrier and in a cool place. IIR, % 5 A 3 1.03 (56)

29 31
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 D297 − 15 (2019) D297 − 15 (2019)
where: beaker to wash the stem of the separatory funnel. Shake and X1.3.2 When the dissolution of the rubber appears to be Repeat this procedure once, or more than once if oxides of
as = absorptivity due to nitrated styrene, allow the layers to separate. Drain the salt solution into the complete, add 5 cm3 of a saturated water solution of bromine nitrogen are still evolved.
Ap = absorbance of the solution, same beaker. Drain the ether layer into a 250-cm3 beaker and slowly evaporate the mixture to a foamy syrup. (For the X1.3.5 Cool the flask, add 50 cm3 of HCl (1 + 6), and
c = concentration of specimen in solution on which absor- containing 4 to 5 g of anhydrous Na2SO4. Add 50 cm3 of ether determination of sulfur in unvulcanized mixtures use 3 cm3 of digest, hot, until dissolution is as complete as possible. Filter
bance is measured, g/dm3, to the separatory funnel and drain a few cubic centimeters into bromine in place of bromine water.) while hot. Wash the filter and dilute the filtrate and washings to
X = average value of the fraction of bound styrene in the 250-cm3 beaker containing the ether extract, to wash the X1.3.3 If organic matter or carbon remains at this point, add about 300 cm3. Add 10 cm3 of saturated picric acid solution,
copolymer as determined in accordance with 57.6.2, stem of the funnel. Swirl ether in the beaker and transfer ether a few cubic centimetres of fuming HNO3 and a few crystals of heat to 90°C, and precipitate the sulfate by dropwise addition
and to another separatory funnel. KClO3 (Caution) and evaporate by boiling. Repeat this opera- of 10 cm3 of BaCl2 solution, while stirring vigorously. Place a
ab = absorptivity of nitrated butadiene = 0.373 at 265 nm, 57.7.5 Repeat extraction of the aqueous layer in the same tion until all carbon is gone and the solution is clear, colorless, watch glass over the beaker and digest the precipitate
0.310 at 273.75 nm, and 0.265 at 285 nm. manner for a total of three extractions, each ether extract being or light yellow. overnight, preferably at 60 to 80°C. Filter the BaSO4 and wash
57.6.4 Record the slit widths used in determining the above dried over the same Na2SO4 and collected in the second X1.3.4 At this point either of the following procedures may with water until the filter is colorless. Dry, ash, and finally
absorbance values and use approximately the same slit widths separatory funnel. be used: ignite the precipitate, at 650 to 900°C, with free access to air.
in the analysis of unknown samples in 57.7. An improvement 57.7.6 Extract the combined ether extracts four times with X1.3.4.1 Procedure A—Place the flask on a wire gauze and Cool in a desiccator and weigh to constant mass.
in precision may result if the final solution used in calibration 50-cm3 portions of NaOH solution (4 g/dm3). Collect the evaporate the mixture to dryness over a Tirrill burner. Then
and in the determination is approximately half of the concen- aqueous extracts in a 250-cm3 volumetric flask. After each X1.4 Calculation—Calculate the percentage of sulfur as
bake the mixture at the highest temperature of the burner until
tration specified in the procedure. Absorbance values will then follows:
extraction, drain a few cubic centimeters of the next portion of all nitrates are decomposed and no more nitrogen oxide fumes
be in the 0.4 to 0.7 range. NaOH solution, before shaking, to rinse the stem of the can be detected. The flask and its contents must be carefully Sulfur, % 5 @ ~ A 3 0.1373! /B # 3 100 (X1.1)
57.7 Procedure: separatory funnel, adding the drainings to the volumetric flask. annealed after this procedure by gradually decreasing the flame
where:
57.7.1 Accurately weigh a specimen of the desired size Dilute to volume with NaOH solution (4 g/dm3). Mix well. or by placing the flask on successively cooler sources of heat.
Pipet a 25-cm3 aliquot into a second 250-cm3 volumetric flask. X1.3.4.2 Procedure B—Evaporate the mixture, cool, add 10 A = grams of BaSO4, and
(Note 18) and extract it with ETA or methyl ethyl ketone B = grams of specimen used.
(vulcanizates only) for 16 to 18 h in a Soxhlet extraction Dilute to volume with NaOH solution (4 g/dm3) and mix well. cm3 of HCl, and evaporate to dryness, avoiding spattering.
apparatus or in the ASTM extraction apparatus described in 57.7.7 With NaOH solution (4 g/dm3) in the blank spectro-
19.2. Alternatively, the specimen may be extracted with either photometer cell and the extract in a matched silica absorption
solvent by the rapid reflux method described in Section 26. If cell, measure the absorbance at 265 nm, 273.75 nm, and X2. QUALITATIVE SCHEME FOR IDENTIFICATION OF RUBBER POLYMERS
this method is used, the specimen shall be cut finely as 285 nm using a spectrometer. The dark current should be
described in the procedure and 25 cm3 of solvent shall be used adjusted before and after each reading. If the dark current is X2.1 Scope X2.3.2.1 Solution I—Dissolve 1.0 g of
for each 0.1 g of specimen. Dry the extracted specimen in a found to have drifted during the reading, the reading should be p-dimethylaminobenzaldehyde and 0.01 g of hydroquinone in
X2.1.1 Appendix X234 contains a semiroutine qualitative
vacuum oven at 100°C for 1 h. repeated.
scheme with confirmatory tests for identification of rubber in 100 cm3 of absolute methanol. Add 5 cm3 of HCl and 10 cm3
rubber products by spot tests of pyrolysis products. of ethylene glycol. Adjust the density to 0.851 Mg/m3 at
NOTE 18—Estimate the specimen mass as follows: 57.8 Calculations:
25/4°C by the addition of a calculated amount of methanol or
57.8.1 If the spectrophotometer has not been calibrated, X2.1.2 This scheme is for use in the identification of IR,
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Specimen mass, g 5 4.5/estimated percent styrene in sample (58) ethylene glycol. The reagent is stable over a period of several
calculate the apparent percentage bound styrene as follows CR, NR, IIR, NBR, and SBR type rubber polymers when each months when stored in a brown bottle.
57.7.23 Transfer the extracted and dried specimen to a (Note 19): is present alone as a rubber or in a rubber product. Use of the X2.3.2.2 Solution II—Dissolve 2.00 g of sodium citrate
125-cm flask having a standard-taper joint, and add 20 cm3 of S 1 5 @ ~ A 265 3 3.829! /B # 2 0.57Y (59) scheme on mixtures of rubber polymers is not recommended (2Na3C6H5O7·11H2O), 0.2 g of citric acid, 0.03 g of bromo-
HNO3 and a few carborundum boiling chips. Place the flask on unless the validity of the test has been confirmed on known cresol green, and 0.03 g of Metanil yellow in 500 cm3 of water.
a cold hot plate, turn the heat on and allow to reflux at a rolling S2 5 @~A 3 3.611! /B # 2 0.45Y (60)
273.75
mixtures.
boil overnight (16 to 18 h) under a water-cooled Graham S3 5 @~A 3 4.018! /B # 2 0.43Y (61) X2.3.3 Procedure—Strip the rubber from any adhering fab-
285
condenser. Turn off heat, pour 10 to 20 cm3 of water into the X2.2 Terminology ric. Place 0.5 g of the sample in a test tube and attach the side
Bound styrene, % 5 ~ S 1 1S 2 1S ! /3 (62) arm. Heat with a microburner or very small Bunsen flame until
top of the condenser, and allow the water to be drawn into the 3
X2.2.1 Definition: the sample begins to decompose. When vapors appear at the
flask as the flask cools. Allow the reaction mixture to cool to where: X2.2.1.1 rubber polymer—the characteristic and major mouth of the side arm, immerse the end beneath the surface of
permit handling of the flask. A = absorbance at the specified wavelength, component of crude natural or synthetic rubber. 1.3 cm3 of Solution II contained in the receiver test tube. After
57.7.3 Transfer to a 400-cm3 beaker, using a stream of water B = mass of specimen, g, and
from a wash bottle to rinse the flask and the standard-taper Y = fraction of styrene-containing copolymer in sample it is evident whether a color change will take place or not,
X2.3 Identification for Pyrolysis Products remove the tube and continue the distillation into 1.3 cm3 of
joints. Add the rinsings to the beaker. Cool the beaker to room (Note 20).
temperature. Add 50 cm3 of NaOH solution (200 g/dm3) to the X2.3.1 Apparatus: Solution I in another test tube. Permit the receivers to cool, and
57.8.2 If the spectrophotometer has been calibrated in X2.3.1.1 Distillation Apparatus—Test tubes, 10 by 75-mm, shake. Note whether the drops sink or float in Solution I and
original flask and again rinse into the beaker, using water. Test
accordance with 57.6, calculate the percentage of bound equipped with a glass condensing tube about 4 mm in outside note the color changes in both solutions. Transfer Solution I to
the solution in the beaker with pH paper. The solution should
styrene content as follows (Note 19): diameter attached to the test tube by means of a cork stopper. a 16- to 150-mm test tube and add 5 cm3 of absolute methanol.
be made strongly acid with HNO3, if the solution is not already
strongly acid at this point. Cool to room temperature. Transfer Bound styrene, % 5 ~ S 1 1S 2 1S 3 ! /3 (63) The condensing tube shall be bent at least 90 deg and shall Heat on a water bath at 100°C for 3 min and note the color that
the solution to a 500-cm3 separatory funnel, rinse the beaker extend about 100 mm beyond the bend. develops. Record all observations, and classify the material by
S1 5 @ ~ 100A x 265/c ! 2 37.3Y # / ~ a s 265 2 0.373! (64)
with water, and add the washings to the separatory funnel.
x
X2.3.1.2 Receiver—Test tubes, 10 by 75-mm, for collecting means of Table X2.1.
(Warning—The skill with which these transfers and the S 2 5 @ ~ 100A x 273.75/c x ! 2 31.0Y # / ~ a s 273.75 2 0.310! (65) distillate.
subsequent extractions are performed will determine the accu- S 3 5 @ ~ 100A x 285/c x ! 2 26.5Y # / ~ a s 285 2 0.265! (66) X2.3.1.3 Test Tubes, 16 by 150-mm. X2.4 Identification by Spot Tests
racy of the analysis.) X2.3.2 Reagents: X2.4.1 Reagents:
where:
57.7.4 Shake the solution with 50 cm3 of diethyl ether and X2.4.1.1 CR-NBR Spot Test Papers—Dissolve 2.0 g of
allow the layers to separate. Drain the lower aqueous layer into cx = concentration of specimen solution on which absor- cupric acetate and 0.25 g of Metanil yellow in 500 cm3 of
the original beaker. Add 25 cm3 of the saturated salt solution to bance is measured, g/dm3, 34 methanol. Impregnate filter paper squares with the solution,
Based on Burchfield, H. P., Individual and Engineering Chemistry, Anal. Ed.,
the ether layer. Drain a few cubic centimetres into the original Ax = absorbance of solution at specified wavelength, dry, and cut into strips.
Vol. 16, 1944, p. 424; and Vol. 17, 1945, p. 806.

33 35
Impresso por: Luiz Gustavo (ADM.) Impresso por: Luiz Gustavo (ADM.)

D297 − 15 (2019)
Pour this diazotized solution into an excess of solution of the liquid that collects in the second test tube. Evaporate the
β-naphthol in NaOH. A vivid scarlet color indicates SBR. methanol from the third tube but do not heat excessively
X2.5.2.5 IIR: toward the end of the evaporation. Boil the residue with 25 cm3
(1) Destructive distillation of IIR yields a white vapor of petroleum ether and filter from insoluble matter. Evaporate
difficult to condense. A light yellow mobile oil may be the filtrate to a small volume, chill in ice, and scratch the sides
obtained. of the vessel to induce crystallization. Dry the mercury
(2) Place about 1 g of dried, acetone-extracted sample in a derivative at 30 to 40°C and determine the melting point (about
test tube provided with a stopper and a bent delivery tube 55°C). Carry out a mixed melting point determination with the
passing through a stopper almost to the bottom of a second test mercury derivative made from known IIR. The derivative is
tube having a side arm. Cool the second tube with ice. By thought to be methoxyisobutyl-mercuriacetate,
means of a delivery tube, connect the side arm of the second
CH3
test tube to a small open test tube containing 0.5 g of mercuric CH3O C CH2·Hg·COOCH3
acetate in 10 to 15 cm3 of methanol. Heat the rubber strongly CH3
so that it is virtually all decomposed and distilled off. Discard

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37
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