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Oxidising properties

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Endpoint:
oxidising solids
Type of information:
experimental study
Adequacy of study:
key study
Study period:
11-20 Jul 2005
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method A.17 (Oxidising Properties (Solids))
GLP compliance:
yes (incl. QA statement)
Remarks:
Hess. Ministerium fur Umwelt, ländlichen Raum und Verbraucherschutz, Wiesbaden, Germany
Contact with:
powdered cellulose
Sample tested:
reference mixture as specified
Remarks:
barium nitrate - cellulose, 50-55% barium nitrate
Parameter:
maximum burning rate
Result:
1 mm/s
Remarks on result:
other: burning time over 200 mm: 200-201 s
Sample tested:
test mixture as specified
Remarks:
test item - cellulose, 60% test item
Parameter:
maximum burning rate
Result:
1.56 mm/s
Remarks on result:
other: burning time over 200 mm: 128 s
Remarks:
The indications of oxidising properties can be considered "false positive": the higher burning rate of the mixtures of test item with cellulose compared to the reference mixtures of barium nitrate with cellulose was not caused by oxidizing properties of the test item but by the combustibility of the melted test item in the porous materials cellulose or kieselguhr.

Two tests mixtures with the test item and cellulose 2:1 burned down in 72, 60 and 65 s on the surface but not the inner material. The test mixture in the middle of the cone remained unaffected.
Two tests mixtures with barium nitrate/cellulose 2:1 burned down completely in 88, 95 and 90 s. Also the inner material of the cone burned down completely.
Due to this burning behavior (cone of the mixture with the test item did not burn down completely) the full test was performed, despite the fact that the test mixture with test item burned down quicker.
Four tests were performed for the reference mixture with 40, 50, 55, and 60 wt.% oxidizer. The results are shown in the following table.

Barium nitrate (%)

Burning time over 200 mm (s)

Burning rate (mm/s)

40

257

0.78

50

200

1.00

55

201

1.00

60

217

0.92

The highest burning rate 1.00 mm/s was found for the mixture with 50 and 55 % oxidizer. All reference mixtures burned down completely.

Mixtures of the test item with cellulose were prepared in 10 %-increments between 10 and 80 wt.% test item and tested. The concentration of 90 wt.% test item was not used due to the fact that for a concentration with 80 wt.% of test item and for the pure test item the mixture could not be ignited with a flame, the test mixture melted. Additional tests with 55, 65 and 100 wt. % test item were performed. The following table shows the results.

Test item (%)

Burning time over 200 mm (s)

Burning rate (mm/s)

10

212

0.94

20

208

0.96

30

215

0.93

40

218

0.92

50

187

1.07

55

148

1.35

60

128

1.56

65

142

1.41

70

433

0.46

80

The test item could not be ignited with a flame, melting

-

90

Due to the fact that the mixture with 80 % of test item could not be ignited, no test was performed

-

100

The test item could not be ignited with a flame, the test item melted

-


For the test mixtures containing 10-55 wt.% the pile did not burn down completely. The pile only burned on the surface. In inner material of the pile remained unaffected. For the test mixtures containing 60- 70wt.% the pile burned down completely.
Six tests were performed for the mixtures with the highest burning rates of 55, 60 and 65 wt.% of test
item.

Test

t(s)

V(mm/s)

t(s)

V(mm/s)

t(s)

V(mm/s)

t(s)

V(mm/s)

t(s)

V(mm/s)

t(s)

V(mm/s)

55%

153

1.31

155

1.29

150

1.33

158

1.27

161

1.24

148

1.35

60%

140

1.43

136

1.47

130

1.54

137

1.46

128

1.56

144

1.39

65%

160

1.25

143

1.40

151

1.32

145

1.38

155

1.29

142

1.41


The highest burning rate 1.56 mm/s was found for the mixture with 60 % test item.
The maximum burning rate of the mixtures of the test item and cellulose (1.56 mm/s) was higher than the maximum burning rate of the reference mixture of cellulose and barium nitrate (1.0 mm/s).
Due to the fact that the maximum burning rate of the mixture of the test item and cellulose was higher than the maximum burning rate of the reference mixture of cellulose and barium nitrate, additional tests in an inert atmosphere (argon) with a glowing coil as ignition source were performed in order to prevent a false positive result.
Additional experiments in an inert atmosphere (Argon) with a concentration of 60 wt. % of the test item showed no flame and no combustion, when the ignition source (glowing coil) was applied. Only the flameless decomposition of the test mixture accompanied with the release of volatile decomposition products was observed.
Reference mixtures of barium nitrate (50, 55 wt.%) and cellulose could be ignited with a flame. In the case of the reference mixture glowing sparks were observed.
Reference mixture with 50 wt.% oxidizer burned down with a flame completely (200 mm) in approximately 300 s (0.67 mm/s) or burned with a flame for 160 mm in approximately 345s (0.46 mm/s), respectively.
A reference mixture with 55 wt.% oxidizer burned with a flame for 50 mm in approximately 60 s (0.83 mm/s).

Additional experiments of test item with kieselguhr and of barium nitrate (55 wt.%) with kieselguhr were performed. The pile only burned on the surface. In inner material of the pile remained unaffected. The following table shows the results.


Test item (%)

Burning time over 200 mm

Burning rate (mm/s)

30

The test item could be ignited with a flame, after burning for approximately 2 s the flame extinguished

-

50

The test item could be ignited with a flame, after burning for 5-10 s the flame extinguished

-

60

150 s

1.33

60

The mixture burned 60 mm within 60 s

1.00

60

The mixture burned:

20 mm in 20 s, 45 mm in 35 s, 85 mm in 65 s,

15 mm in 15 s, 35 mm in 35 s

1.00-1.40

70

90 s

2.22

100

The test item could not be ignited with a flame and melted

-

Barium nitrate (%)

Burning time over 200 mm

Burning rate (mm/s)

55

The test item could not be ignited with a flame, no reaction was observed

-


For the pure test item the test item melted when a flame was applied as ignition source. The melt did not burn due to the limited surface of the melt.
Mixtures of test item (60 and 70 wt.%) with Kieselguhr showed a propagating combustion. For lower concentrations of test item only a local combustion was observed. Due to the fact that Kieselguhr is an inert substance and does not burn it has to be concluded from this test, that the melted test item sustained the combustion if soaked in a porous material. In mixture with Kieselguhr the melted test item was soaked in the porous Kieselguhr and let to an increase of the free surface, which sustained the combustion.
From these tests it can be concluded that also in mixture with cellulose the melted test item was soaked in the porous structure of the cellulose and sustained the combustion. The higher burning rate of the mixtures of test item with cellulose compared to the reference mixtures of barium nitrate with cellulose was not caused by oxidizing properties of the test item but by the combustibility of the melted test item in the porous materials cellulose or Kieselguhr.



Endpoint:
oxidising solids
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
25 Aug - 15 Sep 1993
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
EU Method A.17 (Oxidising Properties (Solids))
GLP compliance:
yes
Remarks on result:
not measured/tested
Remarks:
This test was not carried out due to the associated EC A 10 test result (substance melts when approached by the ignition source)
Endpoint:
oxidising solids
Type of information:
other: expert statement
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: reliable scientific analysis
Qualifier:
according to guideline
Guideline:
EU Method A.17 (Oxidising Properties (Solids))
GLP compliance:
no
Remarks on result:
other: see "Any other information on results incl. tables"

Evaluation of available experimental results:

Kieselguhr is an inert substance and does not burn. In mixture with kieselguhr the molten test item was soaked up by the porous kieselguhr and led to an increase of the free surface which sustained the combustion (like a candlewick).
From these tests it can be concluded that also in the mixture with cellulose the molten test item was soaked into the porous structure of the cellulose and sustained the combustion. The higher burning rate of the mixtures of test item with cellulose compared to the reference mixtures of barium nitrate with cellulose was not caused by oxidizing properties of the test item but by the combustibility of the melted test item in the porous materials cellulose or kieselguhr.
The burning behaviour of the mixture of the test item with cellulose in an inert argon atmosphere showed, that this mixture itself did not burn. For the burning process the oxygen from the surrounding atmosphere is necessary. This test indicates as well that the primarily result is a false positive and the test item has no oxidizing properties.
Within the former study performed by U. Heinz the mixtures of imidacloprid and kieselguhr did not burn. The reason for this finding may be that the used materials were not completely dried: Heinz (2003) gives no data regarding drying of kieselguhr. The kieselguhr material used by Smeykal (2005) was dried by treating at 50 °C under vacuum (1E-03 hPa) until the weight was constant.



Description of key information

The substance demonstrated no oxidizing properties in the sense of the consolidated version of Guideline 67/548/EEC Annex V, Method A. 17.

Key value for chemical safety assessment

Oxidising properties:
non oxidising

Additional information

In an additional expert evaluation it was confirmed that the indications of oxidising properties can be considered "false positive": the higher burning rate of the mixtures of test item with cellulose compared to the reference mixtures of barium nitrate with cellulose was not caused by oxidizing properties of the test item but by the combustibility of the melted test item in the porous materials cellulose or kieselguhr.

In an earlier experiment it was determined that the substance did not support combustion in the sense of EC A.17, on the basis of the test result obtained as stipulated in associated EC Test Guideline A 10 - substance melted when approached by the ignition source. Although the result is methodologically insufficient as such, it supports the outcomes obtained later.

Justification for classification or non-classification

The available data on oxidising properties of the test substance do not meet the criteria for classification according to Regulation (EC) 1272/2008 and are therefore conclusive but not sufficient for classification: it was experimentally proven that that the substance demonstrated no oxidising properties (EU Method A.17). The substance is not an oxidising solid according to Regulation (EC) 1272/2008 (CLP).