170
N. Takada et al. / Journal of Fluorine Chemistry 92 (1998) 167±171
measured with a platinum resistance thermometer with a
precision of Æ0.01 K.
converted into thermal conductivity using the following
empirical equation.
S a
ꢀ
3.6.2. Viscosity
bS c
Viscosity was measured at 296 K with an Ubbelode-type
automatic viscometer. The temperature was maintained
constant within 296.00 Æ 0.01 K. No kinetic energy correc-
tion was necessary. The viscometer was calibrated with a
standard liquid of o-xylene. The viscosity values of o-xylene
used were 0.809 mPa s at 293.15 K, 0.708 mPa s at
303.15 K, and 0.625 mPa s at 313.15 K [22]. The ¯ow time
of each sample was measured at 296.00 K and converted
into dynamic viscosity. The experimental uncertainty was
Æ4%.
whwere ꢀ is the thermal conductivity (mW/mdK) and S is
the detected heat ¯ux (mV)
In this study, measurements were performed on a relative
basis. The equipment constants, a, b, and c, were calibrated
against seven reference gases (H2, CH4, air, N2, Ar, CO2 and
CFC-11), whose reference thermal conductivity values were
collected from reliable data sources [24±30]. The validity of
the calibration curve was examined by HCFC-141b. The
gaseous thermal conductivity of HCFC-141b obtained in
this study agreed with the result by the transient hot-wire
method [31] to within 3%. Judging from this result and the
reproducibility of measurement, the uncertainty of thermal
conductivity obtained was estimated to be less than 4%.
3.6.3. Specific volume
Speci®c volume was measured at 296 K with a Lipkin±
Davison type pycnometer made of glass immersed in a
water bath. First, the volume of the pycnometer containing
about 5 cm3 was determined with degassed pure water.
Next, the sample was charged into the pycnometer and
the mass was determined using an AEU-210 Shimadzu
electronic balance with a precision of Æ0.1 mg. The pycno-
meter was immersed in the water bath and the temperature
of the thermostated water bath was measured with a mer-
cury thermometer with a precision of Æ0.02 K. The weight
of the sample was determined by buoyancy effects. The
experimental uncertainty was Æ0.01%.
3.6.6. Specific heat
Speci®c heat (Cp) was measured at 296.00 K by differ-
ential scanning calorimetry (DSC) using a Perkin±Elmer
DSC 2 [32]. Three DSC scans of the sample, the blank
(empty pan), and the standard (sapphire disc about 40 mg)
were measured under the same conditions. Speci®c heat was
calculated from the difference in DSC signals at the ®nal
temperature (296 K) under consideration of sample size,
standard Cp value, scanning rate (10 K/min), and correction
of pan size. The experimental uncertainty was Æ2%.
3.6.4. Surface tension
Surface tension was measured by means of a Cahn 2000
electrobalance based on the ring method of de Nouy. The
force was measured in a Pyrex glass vessel with a jacket for
circulating thermostated water at 296 K Æ 0.02 K. The
mean circumference (L) of the platinum ring was
5.956 cm. Force was measured with the Cahn 2000 electro-
balance with a precision of Æ0.1 mg. Surface tension (T)
was calculated by the following equation:
Acknowledgements
We wish to thank Mr. Shinichiro Katayama (Toray
Research Center) and Mr. Tadaaki Yako (Sumika Analysis
Service) for their cooperation in the experiment. We would
also like to thank Dr. Kunio Okuhara (RITE) and Mr.
Minoru Akiyama (RITE) for their many useful comments.
This investigation was supported by the New Energy and
Industrial Technology Development Organization (NEDO).
m g F
T
2000 L
where m is maximum mass on a mg basis, g is acceleration
due to gravity 979.7 cm/s2, and F is a correction factor [23].
The experimental uncertainty was Æ0.1 mN/m.
References
[1] J. Molina, S. Rowland, Nature (London) 249 (1974) 810.
[2] A. Sekiya, S. Misaki, Chemtech 26 (1996) 44.
[3] A. Suga, Y. Mochizuki, Y. Gotoh, H. Ito, M. Takahashi, S.
Yamashita, M. Aoyagi, A. Sekiya, S. Kondo, T. Hakuta, Chem.
Exp. 8 (1993) 205.
3.6.5. Gaseous thermal conductivity
The gaseous thermal conductivity of n-C4F9OMe was
measured by the steady state coaxial cylinder method using
a calorimeter (Setaram, C-80D) in the same manner as
described in previous reports [6,8], where the data of
(CF3)3COMe and (CF3)3COEt were reported. After being
¯ushed with sample gas twice, the co-axial cylinder cell,
which was heated up to the measuring temperature (708C),
was ®lled up with a sample gas. After the cell reached
thermal equilibrium, constant energy (100 mW) was sup-
plied to the heater for 1 h. The detected heat ¯ux was
[4] N. Takada, T. Abe, A. Sekiya, Proc. of 15th ISFC, Vancouver,
Canada, 1997 P(2)176.
[5] N. Takada, Y. Mochizuki, E. Fujimoto, T. Iwasaki, A. Sekiya, Proc.
of The 20th Fluorine Conf. of Japan, Nagoya, 1995, p. 107.
[6] N. Takada, H. Yamamoto, S. Matsuo, Y. Tanaka, A. Sekiya, Proc. of
The 21st Fluorine Conf. of Japan, Sappro, 1997, p. 54.
[7] S. Matsuo, Y. Tanaka, M. Ohue, N. Takada, H. Yamamoto,
A. Sekiya, Abstr. of AIRAPT-16 and HPCJ-38, Kyoto, 1997,
p. 153.