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Particle size distribution (Granulometry)

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Reference
Endpoint:
particle size distribution (granulometry)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
19 August 2019 to 12 September 2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 110 (Particle Size Distribution / Fibre Length and Diameter Distributions - Method A: Particle Size Distribution (effective hydrodynamic radius)
Deviations:
no
Qualifier:
according to guideline
Guideline:
ISO 13320 (Particle size analysis - Laser diffraction methods)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
Laser scattering/diffraction
Type of particle tested:
agglomerate
Type of distribution:
mass based distribution
Specific details on test material used for the study:
No further details specified in the study report
Mass median aerodynamic diameter:
>= 210.9 - <= 215.9 µm
Geometric standard deviation:
>= 2.046 - <= 2.076
Key result
Percentile:
D10
Mean:
>= 62.8 - <= 64.7 µm
St. dev.:
0.798
Key result
Percentile:
D50
Mean:
>= 194 - <= 199 µm
St. dev.:
1.7
Key result
Percentile:
D90
Mean:
>= 377 - <= 390 µm
St. dev.:
5.78
No.:
#1
Size:
>= 0.01 - <= 6.72 µm
Distribution:
0 %
No.:
#2
Size:
>= 7.64 - <= 40.1 µm
Distribution:
>= 0.04 - <= 4.32 %
No.:
#3
Size:
>= 45.6 - <= 186 µm
Distribution:
>= 5.43 - <= 46.68 %
No.:
#4
Size:
>= 211 - <= 666 µm
Distribution:
>= 54.1 - <= 100 %
No.:
#5
Size:
>= 756 - <= 3 500 µm
Distribution:
100 %

Full Test Results

 

Run 1

Run 2

Run 3

Run 4

Run 5

Average

STDVP

%STDVP

VWM

211

214

213

208

213

212

N/A

N/A

Mode

254

263

262

258

260

259

N/A

N/A

d10

64.7

64.6

64.3

62.8

64.0

64.1

0.798

1.25

d50 (Median)

197

199

197

194

197

197

1.70

0.863

d90

379

390

387

377

389

385

5.78

1.50

MMAD

213.6

215.9

214.5

210.9

214.3

213.8

1.652

0.8

GSD

2.046

2.062

2.061

2.066

2.076

2.062

0.010

0.5

All particle size results are in μm

0.20 % by volume of sample was seen to be < 10.00 μm

During analysis the optimum dispersion speed 3000 rpm was not strong enough to disperse some of the larger particles through the laser diffraction system because the particles were blocking the inlet of tubing. As a result, data for these particles may not appear in the distribution profile.

Definitions

VWM : volume weighted mean

d10 : 10 % of the test item is less than this particle size

d50 : 50 % of the test item is less than this particle size

d90 : 90 % of the test item is less than this particle size

GSD : geometric standard deviation of the lognormal particle size distribution

MMAD : mass median aerodynamic diameter

Average : calculated from the entirety of the data captured in each run and not a simple arithmetic mean

STDVP : standard deviation of the population

% STDVP : percentage standard deviation of the population

The coefficient of variation for d50 is less than 3 %; d10 and d90 are less than 5 %. Thus repeatability of the characteristic particles in the size distribution is within the acceptable limits as per the ISO 13320-1 test standard.

Conclusions:
0.20 % by volume of sample was seen to be < 10.00 μm
Executive summary:

Particle size distribution analysis was carried out on test substance CAS 577978-76-8. To characterise the particle size distribution of the test item. The analysis was conducted initially using a visual microscope and then undertaken using a Laser Diffraction Particle Size Analyser. This procedure allows for a clearer understanding of the particle characterisation of the test material, such as sample clusters and agglomeration. 

For the optical microscope analysis the test item was observed under 3 conditions:

Direct observation

Under a microscope at 100 x magnification

Under a microscope at 400 x magnification

Standard visual observation

Test item observed to be agglomerated to form large clumps. Several attempts to mechanically break up the clumps without producing particulate fractures were unsuccessful.

Observation at 100 x magnification

The particles appeared to be irregular / amorphous shapes. The smallest individual

particle size was approximately 16 μm and the largest individual size was approximately

3520 μm. Particles and clumps greater than 3500 μm were also observed, therefore sieve

analysis was applied for further analysis.

Observation at 400 x magnification

The test item was observed to be made up of agglomerated particles.

Approximately 102 g of test item could not be transferred to the sieve due to the size of the clumps, as they would not fit through the container collar.

62.1% by weight of the test substance was ≤3550 μm.

Solubility and dispersibility analysis of particle size analysis was carried out in order to select a suitable dispersant. Following this analysis silicon oil was selected for the full solubility and dispersibility testing.

The best dispersant for the laser diffraction analysis is the liquid in which the solubility of the test item is less than 20 mg per litre and in which the test item is well dispersed. The test item proved to be insoluble and well dispersed in silicon oil. Therefore silicon oil was used as the dispersant for the final test.

Laser diffraction particle size analysis was conducted to determine the particle size distribution of Epoxy Resin (CAS 577978-76-8). The test item was initially observed to determine whether sieving of the material was required. A method development for the particle size analysis on the material was then undertaken to obtain the correct parameters for the formal analysis. The method development was employed to identify the most appropriate optical properties for the material, the correct dispersant, dispersion pressures and sample compatibility.

Once these parameters were obtained the test item was then analysed using the Malvern Mastersizer 3000 Laser Diffraction Analyser.

The test was conducted in accordance with ISO 13320:2009 “Particle Size Analysis – Laser Diffraction Methods”, 2009 and CIPAC MT 187 “Particle Size Analysis by Laser Diffraction”, Handbook K, 2007 and took into consideration the OECD guideline 110.

Using the identified parameters, the particle size was analysed over the range 0.01 μm to 3500 μm.

During analysis the optimum dispersion speed 3000 rpm was not strong enough to disperse some of the larger particles through the laser diffraction system because the particles were blocking the inlet of tubing. As a result, data for these particles may not appear in the distribution profile.

The coefficient of variation for d50 is less than 3 %; d10 and d90 are less than 5 %. Thus repeatability of the characteristic particles in the size distribution is within the acceptable limits as per the ISO 13320-1 test standard.

0.20 % by volume of sample was seen to be < 10.00 μm.

Description of key information

0.20 % by volume of sample was seen to be < 10.00 μm

Additional information