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Administrative data

Endpoint:
relative self-ignition temperature (solids)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2019-01-09 - 2019-02-18
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019
Report date:
2019

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
EU Method A.16 (Relative Self-Ignition Temperature for Solids)
Version / remarks:
31 May 2008
Deviations:
yes
Remarks:
refer to 'Principles of method if other than guideline'
Principles of method if other than guideline:
The following deviations from the guideline were documented:
• The heating rate slightly deviated from the value stated in the guideline of 0.5 °C/min (0.57 °C/min). This is considered as uncritical as a nominal heating rate of 0.5 °C/min was adjusted at the instrument and only a minimal deviation was observed.
• For safety reasons the test was stopped before the test item or the oven temperature reached 400 °C. This is considered as uncritical as the stainless steel cube was completely empty.
GLP compliance:
yes (incl. QA statement)

Test material

1
Reference substance name:
Reaction product of Graphite, acid-treated and potassium permanganate
IUPAC Name:
Reaction product of Graphite, acid-treated and potassium permanganate
Test material form:
cream / paste
Specific details on test material used for the study:
Regarding the containing water, the sample can be seen as a paste (liquid) or as a powder (if dried). Freeze drying is not possible because it is not possible to remove the whole water. Strong van der Waals forces pull the layers more and more together keeping the water trapped.

Results and discussion

Relative self-ignition temperature (solids)
Remarks on result:
no self ignition observed under the test conditions

Any other information on results incl. tables

Temperature Data

The temperatures which were measured in the experiment are presented in the following table. As many values were recorded, only the values every 60 minutes (until the ZPA3 was stopped) are presented.

 Time [min.]  Temperature (test item) [°C]  Temperature (oven) [°C]
 5 Start  15.9  17.8
 60  25.8  44.3
 120  43.5  79.7
 180  60.1  114.1
 240  92.9  151.4
 265 End  150.5  165.4

Observation

At approx. 162.3°C the test item expanded explosively out of the oven and spread out powdery all over the oven and the fume hood. Therefore, the test was manually stopped for safety reasons. After the measurement (cooling down of the oven) the cube was inspected and was completely empty.

Results and Discussion

The self-ignition temperature of test item was determined by placing the test item into a stainless steel cube and heating from room temperature to the nominal oven temperature of 400 °C until the test item expanded explosively out of the oven at approx. 162.3°C and spread out powdery all over the oven and the fume hood, the test was manually stopped.

As stated by the sponsor the sample contains, process-related, water. Regarding the containing water, the sample can be seen as a paste (liquid) or as a powder (if dried). Freeze drying is not possible because it is not possible to remove the whole water. Strong van der Waals forces pull the layers more and more together keeping the water "trapped".

The observations above can be explained by when the test item is stored for a long time, the material becomes more and more solid (without losing water), as the strong van der Waals forces pull the layers together more and more, keeping the water "trapped". This is an explanation for the explosive expandation of the test-item. The loss of water needs some more time and temperature to get the water completely out of the sample and this is an abrupt process because of the "trapped" water.

After cooling down the stainless steel cube was completely empty.

Therefore, no Relative Self Ignition Temperature could be stated. Heating above 160 °C should be avoided.

Applicant's summary and conclusion

Conclusions:
No Relative Self Ignition Temperature could be stated. Heating above 160 °C should be avoided.
Executive summary:

The self-ignition temperature of the test item was determined in a GLP-study according to EU method A.16 by placing the test item into a stainless steel cube and heating from room temperature to the nominal oven temperature of 400 °C until the test item expanded explosively out of the oven at approx. 162.3°C oven temperature and spread out powdery all over the oven and the fume hood, the test was manually stopped.

Regarding the containing water the sample can be seen as a paste (liquid) or as a powder (if dried). Freeze drying is not possible because it is not possible to remove the whole water. Strong van der Waals forces pull the layers more and more together keeping the water "trapped".

The observations above can be explained by when the test item is stored for a long time, the material becomes more and more solid (without losing water), as the strong van der Waals forces pull the layers together more and more, keeping the water "trapped". This is an explanation for the explosive expandation of the test-item. The loss of water needs some more time and temperature to get the water completely out of the sample and this is an abrupt process because of the "trapped" water.

After cooling down the steel cube was completely empty.

Therefore, no Relative Self Ignition Temperature of Graphene oxide, reaction product of Graphite, acid-treated and potassium permanganate could be stated. Heating above 160 °C should be avoided.

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