ASTM D3849-22

Standard Test Method for Carbon Black—Morphological Characterization of Carbon Black Using Electron Microscopy

SIGNIFICANCE AND USE
4.1 Carbon black morphology significantly affects the transient and end-use properties of carbon black loaded polymer systems. A carbon black’s particle size distribution is its single most important property, and it relates to degree of blackness, rubber reinforcement, and ability to impart UV protection. For a given loading of carbon black, blackness, reinforcement, and UV protection increase with smaller particle size. Aggregate size and shape (structure) also affect a carbon black's end-use performance, as higher carbon black structure increases viscosity and improves dispersion. The stiffness (modulus) of elastomer systems becomes significantly higher with increasing structure. The preferred method for measuring carbon black morphology (for example, size and shape) is transmission electron microscopy (TEM), but due to the semi-quantitative nature of TEM, it is not suited for mean particle size (MPS) certification. While useful morphological information can be obtained from TEM measurements within a laboratory, due to their inherent between-laboratory variability, TEM generated values should not be used for specification purposes.  
4.2 Certification of carbon blacks for UV protection (weatherability) in certain plastics applications has historically been performed using TEM generated mean particle size values. ASTM Committee D24 has demonstrated that due to challenges with obtaining quantitative primary particle size data, particularly between laboratories, a qualification test based on surface area has been implemented, as detailed in Test Method B.  
4.3 Carbon black aggregate dimensional and shape properties are dependent upon the nature of the system in which the sample is dispersed, as well as the mixing procedure.
SCOPE
1.1 This test method covers (1) the morphological (for example, size and shape) characterization of carbon black from transmission electron microscope images which are used to derive the mean particle and aggregate size of carbon black in the dry (as manufactured) state, from CAB chip dispersion or removed from a rubber compound and (2) the certification of mean particle size using a correlation based on statistical thickness surface area measurements.  
1.2 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-May-2022
• ICS: 83.040.20 - Rubber compounding ingredients
• Technical Committee: D24 - Carbon Black
• Drafting Committee: D24.81 - Carbon Black Microscopy and Morphology

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D3849 − 22
Standard Test Method for
Carbon Black—Morphological Characterization of Carbon
1
Black Using Electron Microscopy
This standard is issued under the fixed designation D3849; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This test method covers (1) the morphological (for 3.1 Definitions:
example,sizeandshape)characterizationofcarbonblackfrom 3.1.1 General:
transmission electron microscope images which are used to
3.1.1.1 carbon black particle—a small spheroidally shaped,
derive the mean particle and aggregate size of carbon black in
paracrystalline,non-discretecomponentofanaggregate;itcan
the dry (as manufactured) state, from CAB chip dispersion or
only be separated from the aggregate by fracturing; carbon
removed from a rubber compound and (2) the certification of
black particle size is a distributional property; therefore, the
mean particle size using a correlation based on statistical
term particle size implies the mean value from multiple
thickness surface area measurements.
measurements.
1.2 The values stated in SI units are to be regarded as the 3.1.1.2 carbon black aggregate—a discrete, rigid colloidal
standard. The values in parentheses are for information only. entity that is the smallest dispersible unit; it is composed of
extensively coalesced particles; carbon black aggregate size is
1.3 This standard does not purport to address all of the
a distributional property; therefore, the term aggregate size
safety concerns, if any, associated with its use. It is the
implies the mean value from multiple measurements.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter- 3.1.1.3 statistical thickness surface area (STSA)—the exter-
mine the applicability of regulatory limitations prior to use.
nalspecificsurfaceareaofcarbonblackthatiscalculatedfrom
1.4 This international standard was developed in accor- nitrogenadsorptiondatausingthedeBoertheoryandacarbon
dance with internationally recognized principles on standard-
black-specific model.
ization established in the Decision on Principles for the
3.1.1.4 glow discharge—a plasma of ionized gas that is
Development of International Standards, Guides and Recom-
formed in a high-voltage field at pressures of about 3 to 20 Pa
mendations issued by the World Trade Organization Technical -3
(25 to 150 × 10 torr); an alternating current (a-c) glow
Barriers to Trade (TBT) Committee.
discharge using air is effective in cleaning and oxidizing the
surface of carbon substrates to improve the wetting character-
2. Referenced Documents
istics of polar vehicles containing pigment dispersions.
2
2.1 ASTM Standards:
3.1.1.5 substrate—athinfilmthatisusedtosupportelectron
D3349Test Method for Absorption Coefficient of Ethylene
microscopespecimens;evaporatedcarbonfilmsarecommonly
Polymer Material Pigmented with Carbon Black
used because of relatively good mechanical strength, stability,
D4483Practice for Evaluating Precision for Test Method
and conductivity.
StandardsintheRubberandCarbonBlackManufacturing
3.1.2 Aggregate Dimensional Properties from Image Analy-
Industries
sis:
D6556Test Method for Carbon Black—Total and External
3.1.2.1 area (A)—the two-dimensional projected area of the
Surface Area by Nitrogen Adsorption
carbon black aggregate image.
3.1.2.2 perimeter (P)—the total boundary length of an
1
This test method is under the jurisdiction ofASTM Committee D24 on Carbon
aggregate.
Black and is the direct responsibility of Subcommittee D24.81 on Carbon Black
Microscopy and Morphology.
3.1.2.3 volume (V)—anestimateofthevolumeofthecarbon
CurrenteditionapprovedJune1,2022.PublishedJuly2022.Originallyapproved
black aggregate using stereological principles.
in 1980. Last previous edition approved in 2014 as D3849–14a. DOI: 10.1520/
D3849-22.
3.1.3 Image Analysis:
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.1.3.1 dilation—the converse of erosion; this process is
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
accomplished by changing any OFF pixel to ON if it has
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. greaterthanapresetminimumofONneighbors,causingimage
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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...

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: D3849 − 14a D3849 − 22
Standard Test Method for
Carbon Black—Morphological Characterization of Carbon
1
Black Using Electron Microscopy
This standard is issued under the fixed designation D3849; 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
1.1 This test method covers (1) the morphological (for example, size and shape) characterization of carbon black from
transmission electron microscope images which are used to derive the mean particle and aggregate size of carbon black in the dry
(as manufactured) state, from CAB chip dispersion or removed from a rubber compound and (2) the certification of mean particle
size using a correlation based on statistical thickness surface area measurements.
1.2 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.
1.3 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.
1.4 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
2.1 ASTM Standards:
D3349 Test Method for Absorption Coefficient of Ethylene Polymer Material Pigmented with Carbon Black
D4483 Practice for Evaluating Precision for Test Method Standards in the Rubber and Carbon Black Manufacturing Industries
D6556 Test Method for Carbon Black—Total and External Surface Area by Nitrogen Adsorption
3. Terminology
3.1 Definitions:
3.1.1 General:
3.1.1.1 carbon black particle—a small spheroidally shaped, paracrystalline, non-discrete component of an aggregate; it can only
be separated from the aggregate by fracturing; carbon black particle size is a distributional property; therefore, the term particle
size implies the mean value from multiple measurements.
3.1.1.2 carbon black aggregate—a discrete, rigid colloidal entity that is the smallest dispersible unit; it is composed of
extensively coalesced particles; carbon black aggregate size is a distributional property; therefore, the term aggregate size implies
the mean value from multiple measurements.
1
This test method is under the jurisdiction of ASTM Committee D24 on Carbon Black and is the direct responsibility of Subcommittee D24.81 on Carbon Black
Microscopy and Morphology.
Current edition approved Nov. 1, 2014June 1, 2022. Published November 2014July 2022. Originally approved in 1980. Last previous edition approved in 2014 as
D3849 – 14.D3849 – 14a. DOI: 10.1520/D3849-14A.10.1520/D3849-22.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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D3849 − 22
3.1.1.3 statistical thickness surface area (STSA)—the external specific surface area of carbon black that is calculated from
nitrogen adsorption data using the de Boer theory and a carbon black-specific model.
3.1.1.4 glow discharge—a plasma of ionized gas that is formed in a high-voltage field at pressures of about 3 to 20 Pa (25 to
-3
150 × 10 torr); an alternating current (a-c) glow discharge using air is effective in cleaning and oxidizing the surface of carbon
substrates to improve the wetting characteristics of polar vehicles containing pigment dispersions.
3.1.1.5 substrate—a thin film that is used to support electron microscope specimens; evaporated carbon films are commonly
used because of relatively good mechanical strength, stability, and conductivity.
3.1.2 Aggregate Dimensional Properties from Image Analysis:
3.1.2.1 area (A)—the two-dimensional projected area of the carbon black aggregate image.
3.1.2.2 perimeter (P)—the total boundary lengt
...