Page 58 - 《橡塑技术与装备》英文版2026年2期

HINA R&P TECHNOLOGY AND EQUIPMENT

Figure 5 Linear relationship between T i , T p , and T f of the sample and the heating rate

-1
observed that as the proportion of PPO in the sample gradually A is the pre-exponential factor, with units of s ; R is the molar
increases, the characteristic curing temperature generally gas constant; and Ea is the apparent activation energy, J/mol.
exhibits a decreasing trend. This implies that in composite Using the Kissinger equation (Equation (5)) and the
material systems, increasing the content of PPO leads to a Crane equation (Equation (6)), the apparent activation
reduction in the temperature threshold required for curing, energy Ea and reaction order n of the curing reaction can be
possibly due to the better chemical reactivity of PPO. determined. According to the data analysis in Table 3, as the
Table 2 Curing characteristic temperature of the sample proportion of PPO in the blend system increases, the reaction
Sample T gel T cure T treat order does not show a significant trend, and the overall kinetic
1 # 88.1 143.8 184.4
2 # 83.3 138.8 182.9 behavior tends towards first-order reaction characteristics. This
3 # 77.1 124.8 134.5
kinetic characteristic suggests good compatibility between
PPO and BNE-200. It indicates that the amount of PPO used
3.3.3 Calculation of curing kinetic parameters will reduce the Ea of the epoxy mixture. A comparison of the
of test samples data between Sample 2# and Sample 3# reveals that when the
The DSC non-isothermal curing kinetic equation is
PPO content is higher, it is mainly PPO that is curing. When
derived from equation (2), and the n-order curing kinetic the PPO content is 60%, the calculated Ea value is the lowest,
model can be described by equation (3). By combining it with
at 75.89 kJ/mol, which is 18.9% lower compared to BNE-200.
the Arrhenius equation (equation (4)), the Kissinger equation
Table 3 Apparent activation energy and reaction order of
(equation (5)) can be obtained. the samples
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d a =k . f(a) (2) Sample Apparent activation energy E a (kJ·mol ) Reaction order n
d t 1 # 83.81 0.93
n
f(a)=(1-a) (3) 2 # 76.32 0.92
E a #
k=A . e R(T+273.15) (4) 3 75.89 0.92
β AR E a
In 2 =In - (5) Under isothermal conditions, there exists a functional
T p E a RT p
dlnβ E a relationship between the degree of cure α and time t, as
1 =- nR (6)
#
d expressed in equation (7). Taking sample 2 as an example, by
T p
-1
7
In equations (2) to (5): d α /d t represents the curing rate; α substituting E a =76.32 kJ/mol, A=7×10 s , and n=0.92 into
denotes the degree of cure; t stands for reaction time, measured equation (7), the time required for the curing system to cure
in minutes; k is the chemical reaction rate constant; T is the under isothermal conditions can be calculated and predicted
thermodynamic temperature, expressed in degrees Celsius; β (equation (8)). 1
] (7)
is the heating rate, measured in degrees Celsius per minute; T p α=1−[1−(1−n)Ate - E a RT 1-n
9.1797×10 3
6
is the peak temperature during curing, also in degrees Celsius; α=1−[1−5.6×10 te T ] 12.5 (8)

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