ASTM D4218-20

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D4218 − 15 D4218 − 20
Standard Test Method for
Determination of Carbon Black Content in Polyethylene
Compounds Byby the Muffle-Furnace Technique
This standard is issued under the fixed designation D4218; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Scope*
1.1 This test method covers the determination of black polyethylene compounds containing channel or furnace black. It is not
applicable to thermal black.
1.2 This test method is not suitable for plastics that char on pyrolysis.
1.3 The values stated in SI units are to be regarded as the standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. Specific hazard statements are given in Section 7.
NOTE 1—There is no known ISO equivalent to this standard.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D883 Terminology Relating to Plastics
D1603 Test Method for Carbon Black Content in Olefin Plastics
D2741 Test Method for Susceptibility of Polyethylene Bottles to Soot Accumulation (Withdrawn 2011)
E456 Terminology Relating to Quality and Statistics
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E2935 Practice for Conducting Equivalence Testing in Laboratory Applications
IEEE/ASTM SI-10 Standard for Use of the International System of Units (SI): The Modern Metric System
3. Terminology
3.1 Definitions—For definitions of plastics terms Terms used in this test method, see standard are defined in accordance with
Terminology D883, unless otherwise specified. For terms relating to precision and bias and associated issues, the terms used in
this standard are defined in accordance with Terminology E456.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 channel black—those carbon blacks produced by a process that operates in an open system in which a multitude of small
diffusion flames burn in air and carbon is deposited on cooled surfaces.
3.2.2 furnace black—those carbon blacks produced using the principle of continuous oxidative combustion in closed systems.
3.2.3 thermal black—those carbon blacks based on a process that uses thermal decomposition in the absence of oxygen and
operates in a closed system. Particles grow very slowly and can become very large and filamentous structures.
3.3 Symbols—Units and symbols used in this test method are those recommended in Practice IEEE/ASTM SI-10.
This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.70 on Analytical Methods (Section
D20.70.01).
Current edition approved Dec. 1, 2015Feb. 1, 2020. Published December 2015March 2020. Originally approved in 1982. Last previous edition approved in 20082015 as
D4218 – 96D4218 – 15.(2008). DOI: 10.1520/D4218-15.10.1520/D4218-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4218 − 20
4. Summary of Test Method
4.1 Black polyethylene compound contained in a disposable aluminum weighing dish is pyrolyzed in a muffle furnace for a short
period. During the pyrolysis of the polymer, the air in the muffle furnace becomes oxygen-deficient to prevent the combustion of
the residual carbon black. Any soot, as defined in Test Method D2741, produced by the initial combustion of the gases is consumed
before the carbon black itself.
4.2 After cooling and weighing for residual carbon black, the dish and contents are reinserted into the muffle furnace to
determine ash content and the results used to determine true carbon black content. This is done only if the compound is suspected
of containing mineral fillers as well as carbon black.
5. Significance and Use
5.1 This test method is capable of yielding duplicate test data, in 20 min or less, for a simple carbon black content determination.
5.2 This test method is suitable for manufacturing quality control, technical service, and research work.
5.3 For referee requirements, the number of replicate measurements is increased. Alternatively, a control sample of known
carbon black content is tested with the unknown sample.
5.4 Test Method D1603 is available for referee testing.
6. Apparatus
6.1 Fume Hood or Vent Hood.
6.2 Muffle Furnace, approximately 100 mm by 100 mm by 100 mm in the three internal dimensions. Furnaces with larger
internal dimensions have been found to be unsuitable. The seal at the door must be free of gaping cracks or chips that will allow
air into the furnace. A muffle furnace with bare heating wires on the floor of the furnace must not be used without additional
electrical safety precautions.
6.3 Screen, 20-Mesh, approximately 120 by 100 mm. Fold down approximately 10 mm of the long dimension to provide a raised
platform to fit inside the muffle furnace.
6.4 Thermocouple-Probe Temperature Controller or Equivalent—This is an integral part of newer muffle furnaces or is
purchased separately to provide improved control on older furnaces.
6.5 Desiccator (for example, 255 mm), with alumina or equivalent desiccant.
6.6 Laboratory Interval Timer, with alarm.
6.7 Disposable Aluminum Weighing Dish—Dishes with crimped sides and tabs on the rim are satisfactory.
6.8 Long Tongs or Tweezers (250 to 300 mm).
6.9 Analytical Balance, capable of measuring to 0.1 mg.
7. Hazards
7.1 Do not use a muffle furnace with bare heating elements on the floor of the furnace. Take steps to make the furnace
electrically safe.
7.2 Do not attempt to test plastics that evolve corrosive fumes on pyrolysis.
7.3 Do not open the muffle furnace door during the test. Opening the door while fumes are being emitted from the door seal
will cause ignition of the fumes.
7.4 This test must be conducted in a fume hood or under a vent hood to remove the resulting fumes.
8. Sample and Test Specimen
8.1 Samples are obtained from the manufacturer’s or purchaser’s sampling regimens or from a specifically identified part.
8.2 The test specimens are in the form of granules or pieces cut from an article such as pipe, jacket, film, molding, etc. Soiled
articles must be washed, and printed articles, such as films, are wiped clean with a suitable solvent.
9. Conditioning
9.1 Conditioning is unnecessary.
10. Procedure
10.1 Place the muffle furnace in a fume hood or under a vent hood.
10.2 Set the controller indicator to 600°C and let it stabilize from 600 to 610°C.
D4218 − 20
10.3 Mark an aluminum weighing dish with an identifying impression on the tab.
10.4 Place the dish on the screen in the muffle furnace and burn off the surface oil for 2 min, as indicated by timer.
10.5 Transfer the Using the tongs, transfer the dish to the desiccator and let it cool for at least 2 min.
10.6 Weigh the dish accurately on the analytical balance. Record the results as W .
10.7 Add about 1 g of specimen and reweigh the dish and contents accurately. Record the results as W .
10.8 Place the Using the tongs, place the weighed dish and contents into the muffle furnace and set the interval timer for 3 min.
If there are no known ashable fillers, then this time is sufficient. If there are other or additional fillers that will oxidize further, then
follow the procedure at 10.11 to obtain a more complete pyrolysis.
10.9 After the elapsed time, using the tongs, remove the dish from the muffle furnace and place it in the desiccator to cool for
at least 2 min. Longer cooling periods do not affect the test.
10.10 Reweigh the dish and remaining carbon black accurately. Record the results as W .
10.11 If ashable miner
...