Chemistry Reference
In-Depth Information
Thermogravimetric analysis (TGA) is a convenient, and the most often used, method
to evaluate the thermal stability and degradation behaviours of polymers. The
temperatures at which 5 and 10% weight losses were incurred (
T
5%
and
T
10%
)
are
given in
Table 1.2
. It is noted that
T
5%
for the epoxy resins cured with CHDA and
BTCA were approximately 330 and 340 °C respectively. For the DER332/MMP
and DER332/MPA systems, the values of
T
5%
were approximately 312
and 320 °C
respectively. This result indicates that epoxies cured with a rosin-based curing agent
exhibited slightly lower thermal degradation temperatures compared to those of the
epoxies cured with commercial petroleum-based curing agents. The activation energy
of cure reaction for each curing system suggests that rosin-derived curing agents
had very similar curing reactivity and energy consumption to their petroleum-based
analogues.
Table 1.2 Comparison of thermal properties of epoxy resins cured with
different curing agents
E
a
(kJ/mol)
DMA (
o
C)
TGA (
o
C)
1
System
Kissinger
Ozawa
T
g
T
5%
T
10%
CHDA/DER332
74.8
75.6
113.7
330.3
351.2
MMP/DER332
73.3
76.9
123.6
312.1
334.9
BTCA/DER332
67.5
69.8
178.0
339.8
356.4
76.3-H
72.9-L
78.6-H
74.2-L
186.1
---
319.5
---
340.7
---
MPA/DER332
2
1
T
5%
and
T
10%
: temperatures of 5 and 10% degradation.
2
H and L represent the activation energy (
E
a
)
of the reactions occurring at the lower
and higher temperatures, respectively, during DSC scanning.
Reproduced with permission from X. Liu, W. Xin and J. Zhang,
Green Chemistry,
2009,
11
, 1018. 2009, Royal Society of Chemistry [6].
