Civil Engineering Reference
In-Depth Information
where
f
(
a
) is a function depending on the kinetic model obeyed by the
reaction and
A
is a pre-exponential factor in the Arrhenius expression for
the rate constant,
E
is the apparent activation energy,
R
is the gas constant,
and
T
is the absolute temperature.
Figure 21.
Comparison of mass loss curves for dehydration using conventional TG at 5°K
min
-1
with CRTA methods.
[14]
)] versus
I/T
for various functions of a should be linear with the slope of
E
/
R
. The
activation energy can then be obtained from a single CDRC experiment. It
is apparent then that the general shape of the experimental curve,
Assuming the term ln(
A
/
C
) is a constant, plots of ln[
f
(
α
α
versus
T
contains useful information concerning the actual dehydration
mechanism. A number of model functions, for
f
(
α
) is given in Table 1.
