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Particle size distribution (Granulometry)

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Endpoint:
particle size distribution (granulometry)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Qualifier:
according to guideline
Guideline:
ISO 13320 (Particle size analysis - Laser diffraction methods)
GLP compliance:
no
Other quality assurance:
ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)
Type of method:
Laser scattering/diffraction
Type of particle tested:
aggregate
Type of distribution:
counted distribution
Key result
Percentile:
D10
Mean:
17 µm
St. dev.:
0
Remarks on result:
other: dispersed in air, % by volume
Remarks:
Std.dev. not given
Key result
Percentile:
D50
Mean:
58 µm
St. dev.:
0
Remarks on result:
other: dispersed in air, % by volume
Remarks:
Std.dev. not given
Key result
Percentile:
D90
Mean:
121 µm
St. dev.:
0
Remarks on result:
other: dispersed in air, % by volume
Remarks:
Std.dev. not given
Key result
Percentile:
D10
Mean:
2.2 µm
St. dev.:
0
Remarks on result:
other: dispersed in water
Remarks:
Std.dev. not given
Key result
Percentile:
D50
Mean:
12 µm
St. dev.:
0
Remarks on result:
other: dispersed in warter
Remarks:
Std.dev. not given
Key result
Percentile:
D90
Mean:
65 µm
St. dev.:
0
Remarks on result:
other: dispersed in water
Remarks:
Std.dev. not given
Conclusions:
Carbon black (PrintexG) forms micrometer-sized aggregates when dispersed in water and air; D50 of 12 µm and 58 µm, respectively
Executive summary:

Carbon black (PrintexG) forms micrometer-sized aggregates when dispersed in water and air; D50 of 12 µm and 58 µm, respectively

Endpoint:
particle size distribution (granulometry)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Qualifier:
according to guideline
Guideline:
ISO 13320 (Particle size analysis - Laser diffraction methods)
GLP compliance:
no
Other quality assurance:
ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)
Type of method:
Laser scattering/diffraction
Type of particle tested:
aggregate
Type of distribution:
counted distribution
Key result
Percentile:
D10
Mean:
10 µm
St. dev.:
0
Remarks on result:
other: dispersed in air, % by volume
Remarks:
Std.dev. not given
Key result
Percentile:
D50
Mean:
32 µm
St. dev.:
0
Remarks on result:
other: dispersed in air, % by volume
Remarks:
Std.dev. not given
Key result
Percentile:
D90
Mean:
82 µm
St. dev.:
0
Remarks on result:
other: dispersed in air, % by volume
Remarks:
Std.dev. not given
Key result
Percentile:
D10
Mean:
4.8 µm
St. dev.:
0
Remarks on result:
other: dispersed in water
Remarks:
Std.dev. not given
Key result
Percentile:
D50
Mean:
13 µm
St. dev.:
0
Remarks on result:
other: dispersed in warter
Remarks:
Std.dev. not given
Key result
Percentile:
D90
Mean:
80 µm
St. dev.:
0
Remarks on result:
other: dispersed in water
Remarks:
Std.dev. not given
Conclusions:
Carbon black (Printex 25) forms micrometer-sized aggregates when dispersed in water and air; D50 of 13 µm and 32 µm, respectively
Executive summary:

Carbon black (Printex 25) forms micrometer-sized aggregates when dispersed in water and air; D50 of 13 µm and 32 µm, respectively

Endpoint:
particle size distribution (granulometry)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Qualifier:
according to guideline
Guideline:
ISO 13320 (Particle size analysis - Laser diffraction methods)
GLP compliance:
no
Other quality assurance:
ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)
Type of method:
Laser scattering/diffraction
Type of particle tested:
aggregate
Type of distribution:
counted distribution
Key result
Percentile:
D10
Mean:
5.7 µm
St. dev.:
0
Remarks on result:
other: dispersed in air, % by volume
Remarks:
Std.dev. not given
Key result
Percentile:
D50
Mean:
21 µm
St. dev.:
0
Remarks on result:
other: dispersed in air, % by volume
Remarks:
Std.dev. not given
Key result
Percentile:
D90
Mean:
56 µm
St. dev.:
0
Remarks on result:
other: dispersed in air, % by volume
Remarks:
Std.dev. not given
Key result
Percentile:
D10
Mean:
4.9 µm
St. dev.:
0
Remarks on result:
other: dispersed in water
Remarks:
Std.dev. not given
Key result
Percentile:
D50
Mean:
13 µm
St. dev.:
0
Remarks on result:
other: dispersed in warter
Remarks:
Std.dev. not given
Key result
Percentile:
D90
Mean:
80 µm
St. dev.:
0
Remarks on result:
other: dispersed in water
Remarks:
Std.dev. not given
Conclusions:
Carbon black (Printex 90) forms micrometer-sized aggregates when dispersed in water and air; D50 of 13 µm and 21 µm, respectively
Executive summary:

Carbon black (Printex 90) forms micrometer-sized aggregates when dispersed in water and air; D50 of 13 µm and 21 µm, respectively

Endpoint:
particle size distribution (granulometry)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Qualifier:
according to guideline
Guideline:
ISO 13320 (Particle size analysis - Laser diffraction methods)
GLP compliance:
no
Other quality assurance:
ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)
Type of method:
Laser scattering/diffraction
Type of particle tested:
aggregate
Type of distribution:
counted distribution
Key result
Percentile:
D10
Mean:
6.1 µm
St. dev.:
0
Remarks on result:
other: dispersed in air, % by volume
Remarks:
Std.dev. not given
Key result
Percentile:
D50
Mean:
18 µm
St. dev.:
0
Remarks on result:
other: dispersed in air, % by volume
Remarks:
Std.dev. not given
Key result
Percentile:
D90
Mean:
39 µm
St. dev.:
0
Remarks on result:
other: dispersed in air, % by volume
Remarks:
Std.dev. not given
Key result
Percentile:
D10
Mean:
5.6 µm
St. dev.:
0
Remarks on result:
other: dispersed in water
Remarks:
Std.dev. not given
Key result
Percentile:
D50
Mean:
13 µm
St. dev.:
0
Remarks on result:
other: dispersed in warter
Remarks:
Std.dev. not given
Key result
Percentile:
D90
Mean:
84 µm
St. dev.:
0
Remarks on result:
other: dispersed in water
Remarks:
Std.dev. not given
Conclusions:
Carbon black (Printex 95) forms micrometer-sized aggregates when dispersed in water and air; D50 of 13 µm and 18 µm, respectively
Executive summary:

Carbon black (Printex 95) forms micrometer-sized aggregates when dispersed in water and air; D50 of 13 µm and 18 µm, respectively

Endpoint:
particle size distribution (granulometry)
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Qualifier:
according to guideline
Guideline:
other: ASTM methods
Principles of method if other than guideline:
Carbon Black and amorphous silica were subjected to uniaxial compression, mixing into rubbers, and intense ultrasonication. Initial and processed states were compared by TEM/ AIA.
GLP compliance:
no
Type of method:
microscopic examination
Type of particle tested:
aggregate
Conclusions:
For industrial aciniform aggregates, breakdown of aggregates with liberation of nodules is not an issue in severe mechanical treatment. Aggregate structures that are able to withstand these intense mechanical forces are unlikely to be broken down in a biologic system in which forces are very weak by comparison.

Description of key information

Carbon black aggregates are the smallest dispersible units measuring ~ 80 to ~800 nm. Aggregate structures are able to withstand intense mechanical forces. As a result of the fusion of their source (primary) particles, the aggregates do not break down to release their source constituent or primary particles, even after severe mechanical treatment or in lung fluid (Albers et al. 2015; Creutzenberg et al. 2012; Gray and Muranko 2006; IARC 2010; Levy et al. 2012).

Particle size distributions were measured for representative carbon black samples with high (Printex 90 and 95) and low surface area (Printex 25 und G) to cover the particle size range found for industrially manufactured carbon black.

 Result (diameter) d10  d50  d90
Printex 25  10 µm  32 µm   82 µm
Printex G 17 µm   58 µm  121 µm
Printex 90   5.7 µm  21 µm  56 µm
 Printex 95 6.1 µm   18 µm  39 µm

 

References:

Albers P, Maier M, Reisinger M, Hannebauer B, Weinand R (2015) Physical boundaries within aggregates – differences between amorphous, para-crystalline, and crystalline structures. Crystal Research and Technology 50(11):846-865 doi:10.1002/crat.201500040;

Creutzenberg O, Bellmann B, Korolewitz R, et al. (2012) Change in agglomeration status and toxicokinetic fate of various nanoparticles in vivo following lung exposure in rats. Inhal Toxicol 24(12):821-30 doi:10.3109/08958378.2012.721097;

Gray CA, Muranko H (2006) Studies of robustness of industrial aciniform aggregates and agglomerates--carbon black and amorphous silicas: a review amplified by new data. J Occup Environ Med 48(12):1279-90;

Levy L, Chaudhuri IS, Krueger N, McCunney RJ (2012) Does carbon black disaggregate in lung fluid? A critical assessment. Chem Res Toxicol 25(10):2001-6 doi:10.1021/tx300160z;

Additional information

Primary particles are formed only within the first milliseconds of carbon black production in the production chamber, then they coalesce and fuse with other primary particles to form covalent bonds which result in strongly bonded aggregates. Typically, primary particles therefore do not physically exist in carbon black once it has left the production chamber and the aggregate is the discrete entity with well-defined physical boundaries, i.e., the particle. Typically, carbon black is shipped and placed on the market in the form of pellets (i.e., compressed agglomerates) to facilitate handling and to reduce the generation of dust. The size of pellets generally falls between 0.1 and several micrometers. The true sizes of agglomerates of carbon black as put on the market is challenging to measure because pre-measurement treatment of test samples, for example, by stirring or sonication, leads to the disintegration of the agglomerate particles to aggregates or smaller-sized agglomerates (Gray and Muranko 2006).

Although measurement of mean particle sizes has historically been performed using TEM, this is not a suitable method for obtaining quantitative particle size data, especially because dimensional and shape properties of carbon black aggregates are dependent upon the nature of the system in which the sample is dispersed, as well as the mixing procedure. Measuring primary particle size distributions using TEM is technically not possible.

Reference:

Gray CA, Muranko H (2006) Studies of robustness of industrial aciniform aggregates and agglomerates--carbon black and amorphous silicas: a review amplified by new data. J Occup Environ Med 48(12):1279-90;