HAN et al.
that of CB, but they all showed better catalytic effects
than 3% content of CB or FS.
studies suggest that the course of mass loss of AP con-
sists of several independent processes. Thus, it would be
possible to detect the products produced in each process
by selecting the heating rate and the upper limit of tem-
perature properly. An infrared spectroscopic approach
enables one to obtain direct information about the mo-
lecular structure and to assign to unknown products with
high-boiling temperature. Typical infrared spectra are
shown in Fig. 5 for the wave number from 800 to
4000 cm–1. All the measurements are conducted in a
flowing nitrogen atmosphere (40 mL min–1). The sam-
ple masses were about 1 mg and heated to 500°C using a
heating rate of 50°C s–1.
In Fig. 5a, the 3276 and 1424 cm–1 can be assigned
to N–H stretching vibration and N–H bending band in
the ammonia, the 2248 cm–1 can be related to N2O atmo-
sphere, the 1634 and 1599 cm–1 are belonged to NO2 at-
mosphere, the 1085 and 633 cm–1 are assigned to ClO–4
anion which occurred at 270°C. No C=O vibration peak
is found during the whole decomposition process of AP,
the appearance of N–H and ClO–4 vibration absorbance
peaks elucidates that the thermal decomposition of AP
is based on the proton transfer from ammonia cation to
perchloric acid anion.
However, in Fig. 5b some new absorption peak
is observed at 2345 (belonged to CO2), 2201 (be-
longed to CO), 1715 (belonged to HCHO), 1311 and
878 cm–1 (belonged to HNO3), which do not find in
the decomposition process of pure AP.
In Fig. 5c the absorbance peak of N–H stretching
vibration is not obvious but the absorbance peak that as-
signed to CO2 is very strong and there is not any new
peak different from that of AP with 5% CB. In Fig. 5d
there is not any new peak different from Fig. 5c.
Kinetics of decomposition of AP with 5% CB and 5%
FS additives
A specific feature of thermal decomposition of AP is
extremely sensitive to the action of various additives.
With the objection to obtain the kinetics of the
high-temperature decomposition of AP with addi-
tives, we studied the influences of four heating rates
on thermal decomposition of AP with CB and FS ad-
ditives. In order to make the comparison obviously,
we used 5% content of CB and FS. The basic equation
used to estimate the activation energy of AP-additive
mixtures decomposition is:
é AE ù
E
logb=-2.315+log
-0.4567
ê
ú
RF (a )
(Ozawa method [13])
RT
ë
û
where b is the programmed heating rate (°C min–1), E
is the activation energy, A is the pre-exponential fac-
tor and R is the gas constant, F(a) is fitted as a func-
tion of conversion degree (a) and T is the temperature
at a constant conversion degree, which in the TG
curve is the temperature at a=0.5. Thus, as the heating
rate is increased, the reaction peak shifts to higher
temperature and therefore an estimation of the activa-
tion energy may be made. The pre-exponential factor
A is deduced in the first order using the equation:
æ
ç
ç
è
ö
bE
2
RTmax
E
æ
ö
÷
÷
÷
ø
A=
exp
ç
RT
è
ø
The activation energy of AP with 5% CB is
slightly larger than that of AP with 5% FS. In the
presence of FS the activation energy of the thermal
decomposition reaction is reduced by 37% as shown
in Table 4. It is seen that the maximum rate constants
are determined by the following expressions:
Ignition temperature measurement
The ignition temperatures of pure AP, AP with
5% CB, AP with 5% FS, AP with 5% EFS and AP
with 5% C60 mixtures are shown in Table 5. The sam-
ple masses are about 1 g with a dimension of
1 cm×0.5 cm×0.5 cm during one experiment. The ex-
periments were carried out in a tube furnace and the
voltage was regulated to 172.5 V through a trans-
former with a voltage range of 0~250 V. The samples
were placed at a distance of 1 cm to the rear of the
tube furnace.
with CB, K=3.18·1016exp(–192300/RT) min–1
with FS, K=3.02·1015exp(–185800/RT) min–1
IR analysis
The infrared spectroscopic measurements of the gaseous
products were conducted under 1 atmosphere of nitro-
gen pressure. The results of the thermal decomposition
Table 4 Kinetic parameters for the thermal decomposition of AP-additive mixtures
Samples
Activation energy/kJ mol–1
Pre-exponential factor/min–1
Correlation coefficient; R
AP
293 [13]
192.3
AP+5% CB
AP+5% FS
3.18·1016
3.02·1015
0.986
0.999
185.8
554
J. Therm. Anal. Cal., 91, 2008