Reaction mass of 1,3-dimethyl-1,1,3,3-tetraphenyldisiloxane and 1,3,3,5-tetramethyl-1,1,5,5-tetraphenyltrisiloxane and 1,3,3,5,5,7-hexamethyl-1,1,7,7-tetraphenyltetrasiloxane

Vapour pressure

Link to relevant study record(s)

Reference

Endpoint:

vapour pressure

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Sept-Oct 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 104 (Vapour Pressure Curve)

Qualifier:

according to guideline

Guideline:

EU Method A.4 (Vapour Pressure)

GLP compliance:

yes (incl. QA statement)

Type of method:

effusion method: Knudsen cell

Key result

Test no.:

#4

Temp.:

75 °C

Vapour pressure:

0.01 Pa

Key result

Test no.:

#5

Temp.:

90 °C

Vapour pressure:

0.035 Pa

Key result

Test no.:

#6

Temp.:

105 °C

Vapour pressure:

0.109 Pa

Key result

Test no.:

#7

Temp.:

120 °C

Vapour pressure:

0.355 Pa

Key result

Test no.:

#8

Temp.:

135 °C

Vapour pressure:

1 Pa

Key result

Temp.:

20 °C

Vapour pressure:

0 Pa

Remarks on result:

other: calculated based on measured values at higher temperature

Key result

Temp.:

25 °C

Vapour pressure:

0 Pa

Remarks on result:

other: calculated based on measured values at higher temperature

Vapour pressure was examined at eight different temperatures. Five temperatures could be evaluated as they showed reproducible weight loss. For these temperatures, 1/T was plotted against log (p).

Vapour Pressures (Effusion Method)

Experiment	T	Mean p	Standard Deviation P	RSD p
No.	K	Pa	Pa	%
4	348.2	9.99E-03	3.11E-04	3.1%
5	363.2	3.48E-02	9.16E-03	26.3%
6	378.2	1.09E-01	1.13E-02	10.4%
7	393.2	3.55E-01	4.21E-02	11.8%
8	408.2	1.00E+00	1.31E-01	13.0%

RSD = Relative Standard Deviation

 

The graph 1/T vs. log (P) shows a straight line with a correlation coefficient of - 0.9998.

 

For the test item, the following vapour pressures at 20 °C and at 25 °C were calculated from the regression equation:

Vapour pressure at 20 °C:                        2.65* 10^-05Pa

Vapour pressure at 25 °C:                        4.95* 10^-05Pa

Conclusions:

Vapour pressure at 20 °C: 2.65E-05 Pa
Vapour pressure at 25 °C: 4.95E-05 Pa

Executive summary:

The vapour pressure of the test item was determined at eight different temperatures (30, 45, 60, 75, 90, 105, 120 and 135 °C) according to OECD 104 resp. EU A.4 using the effusion method (weight loss).

Experiment 1 - 3 (nominal temperature 30 – 60 °C) showed only a poor reproducible weight loss. When visible contaminations, caused by explosive evaporation of the test item, were observed, the cells were meticulously cleaned and weighed. This weight was used as initial weight for the subsequent measurements. To avoid bias, these measurements were not used for calculations.

Five experiments (nominal temperature 75 - 135 °C) could be evaluated as they showed relevant and reproducible weight loss. All evaluated experiments showed good repeatability, giving relative standard deviations of less than 27 % (limit value from the guideline 30 %) and good correlation.

Therefore, the result of the test can be considered valid.

Description of key information

The vapour pressure of the test item was determined at eight different temperatures (30, 45, 60, 75, 90, 105, 120 and 135 °C) according to OECD 104 resp. EU A.4 using the effusion method (weight loss).

Five experiments (nominal temperature 75 - 135 °C) could be evaluated as they showed relevant and reproducible weight loss. All evaluated experiments showed good repeatability, giving relative standard deviations of less than 27 % (limit value from the guideline 30 %) and good correlation.

Therefore, the result of the test can be considered valid.

For the test item, the following vapour pressures at 20 °C and at 25 °C were calculated from the regression equation:

Vapour pressure at 20 °C:                        2.65E-05 Pa

Vapour pressure at 25 °C:                        4.95E-05Pa

Key value for chemical safety assessment

Vapour pressure:

0 Pa

at the temperature of:

20 °C