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Vapour pressure

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Reference
Endpoint:
vapour pressure
Type of information:
experimental study
Adequacy of study:
key study
Study period:
04.01.2005 - 13.01.2005
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 104 (Vapour Pressure Curve)
Version / remarks:
adopted on 27 July 1995 and EU test method A.4 [Directive 92/69/EEC, Official Journal L 383 A 1992] with the vapour pressure balance
Deviations:
no
Principles of method if other than guideline:
A sample of the test item is heated in a small furnace, placed in an evacuated bell jar. The furnace is
covered by a lid which carries small holes of known diameters, The vapour of the substance,
escaping through one of the holes, is directed onto a balance pan of highly sensitive balance which is
also enclosed in the evacuated bell jar. The momentum of the vapour jet acts as a force on the
balance.

Procedure:
Apparatus:
Vapour pressure balance: Netzsch Typ 433 (Netzsch)
Pressure measurement: Combivac 1T 230 (Leybold)
Vacuum pump: Trivac B, Typ D 25 B (Leybold)
Molecular vacuum pump: Turbovac 450 (Leybold)
Temperature regulation: Netzsch 41 0 (Netzsch)
Parameters:
Degassing: 180 min at 30 °C (vacuum)
Cross-section blende na. 1 : 6.0089 mm² (starting at -10 "C)
Vacuum at initial temperature: 4 * 10 E-7 hPa
Initial temperature: -10 "C
Holding time: 10 min
Heating rate: 1 °C/min
Final temperature: 30 "C
GLP compliance:
yes
Type of method:
effusion method: vapour pressure balance
Specific details on test material used for the study:
Supplier: Evonik Röhm GmbH, Germany
Batch No.0011141123
Purity: 99.4
%
Impurities: 0.46% water
ca. 300 ppm methacrylic acid
Key result
Temp.:
20 °C
Vapour pressure:
0.002 hPa

The sample was degassed under vacuum. The rneasurements started at the initial temperature and the temperature was increased stepwise.

  Temperature [°C] Inverse temperature x 1000 [K -1]  Vapour pressure (*) [hPa]     
  -10  3.800  0.000058   
  3.661  0.00010   
  3.595  0.00034   
  10  3.532  0.00069   
  15  3.470  0.0010   
  20  3.411  0.0015   
  25  3.354  0.0026   
  30  3.299  0.0054   
         
Calculated pressure:  20  3.411  0.0015   

(*) Mean value of triplicate measurements

Due to the tendency of the test item to sublimate at higher temperatures the determination of the vapour pressure started below room temperature at -10°C.

The vapour pressure of Methacrylamide at 20°C was interpolated graphically in the log p vs 1/T plot. It corresponds to the measured value at 20 °C of 1.5 * 10E-3 hPa.

Conclusions:
The vapour pressure of Methacrylamide was determined according to OECD guideline no. 104 [adopted an 27 July 1995 and EU test method A.4
[Directive 92/69/EEC, Official Journal L 383 A 1992 with the vapour pressure balance method.
Vapour pressure was 1.5 x 10 E-3 hPa at 20 °C
Executive summary:

The vapour pressure of Methacrylamide was determined according to OECD guideline no. 104 [adopted on 27 July 1995 and EU test method A.4 [Directive 92/69/EEC, Official Journal L 383 A 1992] with the vapour pressure balance method. The vapour pressure was determined to be 1.5 x 10 E-3 hPa at 20 °C

Description of key information

The vapour pressure of Methacrylamide was determined according to OECD guideline no. 104 [adopted on 27 July 1995 and EU test method A.4 [Directive 92/69/EEC, Official Journal L 383 A 1992] with the vapour pressure balance method. The vapour pressure was determined to be 0.0015 hPa at 20 °C

Key value for chemical safety assessment

Vapour pressure:
0.15 Pa
at the temperature of:
20 °C

Additional information