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Vapour pressure

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Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
disregarded due to major methodological deficiencies
Study period:
15/06/2009 – 02/07/2009
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
unsuitable test system
Remarks:
The experimental method used for the vapour pressure determination was not suitable and the recommended range of 10+E2 to 10+E5 Pa was inappropriate for the test substance. Therefore, while the report from Chilworth Technology Ltd., (Report no. GLP102942AR1V1/09) is considered to be Klimisch 2 reliability rating it must be ignored. The second study carried out at LAUS is the suitable method for this kind of substance.
Qualifier:
according to guideline
Guideline:
EU Method A.4 (Vapour Pressure)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
isoteniscope
Key result
Temp.:
20 °C
Vapour pressure:
1.305 mBar
Remarks on result:
other: mean value

Full test results:

 Temp / °C Temp / K  P / mbar  ** P /Pa 
          Run 2
 *20  293.15  1.29  129
 65.0  338.15  7  700
 80.0  353.15  12  1200
 95.0  368.15  18  1800
 110.0  383.15  26  2600
 125.0  398.15  39  3900
          Run 3
 *20  293.15  1.32  132
 66.4  339.55  11  1100
 81.5  354.65  21  2100
 95.8  368.95  32  3200
 111.0  384.15  55  5500
 125.9  399.05  84  8400

*: Determined by extrapolation

**: Calculated

Run 1 was not reported due to potential crossover of notrogen into the sample vapour phase.

Result : 1.305 mbar at 20°C

Conclusions:
Result : 1.305 mbar at 20°C (mean value)
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Experimental starting date: 12 May 2010 and Experimental Completion test: 06 June 2010.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method A.4 (Vapour Pressure)
Deviations:
yes
Remarks:
OECD proposes a temperature range of 0 – 50 °C or 120 – 150 °C. This range was ex-tended in the experimental run as several test items were examined simultaneously, and other test items showed much higher vapour pressures.
GLP compliance:
yes (incl. QA statement)
Type of method:
effusion method: by loss of weight or by trapping vaporisate
Remarks on result:
other: The following estimated vapour pressures at 20°C and at 25°C were calculated from the regression equation: Vapour pressure at 20°C: 5.92 * 10-03 Pa Vapour pressure at 25°C: 9.55 * 10-02

The vapour pressure of 4,4'MDI Homopolymer was determined following EU A.4 by the effusion method (weight loss).

Vapour pressure was examined in eight experiments at different temperatures. Four tem-peratures could be evaluated as they showed reproducible weight loss. For these tem-peratures, 1/T was plotted against log (P).

Table: Vapour Pressures (Effusion Method)

Experiment

 T  P  Stand. Dev. P  RSD P
 No.  K  Pa  Pa  %
 4  321.5  7.43E-02  1.52E-02 20.5% 
 5 335.3   1.95E-01  1.29E-02  6.6%
 6 349.2  6.71E-01  1.19E-01  17.8%
 7 363.0  1.34E-00  1.97E-01  14.8%

In this table, E-03 represents * 10-3.

The graph 1/T vs. log (P) shows a straight line with a correlation coefficient of -0.996.

For the test item HPU7: 4,4'MDI Homopolymer, the following vapour pressures at 20 °C and at 25 °C were calculated from the regression equation:

Vapour pressure at 20 °C: 5.92 * 10-03 Pa

Vapour pressure at 25 °C: 9.55 * 10-03 Pa

Conclusions:
The following estimated vapour pressures at 20°C and at 25°C were calculated from the regression equation:
Vapour pressure at 20°C: 5.92 * 10-03 Pa
Vapour pressure at 25°C: 9.55 * 10-03 Pa

Description of key information

The experimental method used at Chilworth Technology Ltd. for vapour pressure determination was not suitable and the recommended ranges were inappropriate. Therefore, the study from Chilworth Technology Ltd., is considered to be Klimisch 3 reliability rating and it must be ignored.
The following estimated vapour pressures at 20°C and at 25°C were calculated from the regression equation:
Vapour pressure at 20°C: 5.92 * 10-03 Pa
Vapour pressure at 25°C: 9.55 * 10-03 Pa

Key value for chemical safety assessment

Additional information