Chemistry Reference
In-Depth Information
storage modulus than the resin cured with N-(4-carboxyphenyl)trimellitimide (NCPT),
suggesting that the former two possessed more rigid molecular structures than the
latter. The
T
g
of each cured epoxy was measured from the peak temperature in the
tan δ plot and is listed in
Table 1.3
. Compared with the DER6224/NCPT system,
the DER6224/RMID and DER6224/D-RMID systems exhibited much higher glass
transition temperatures. These results could probably be attributed to the large
hydrogenated phenanthrene ring in RMID and D-RMID, which seemed to impose
more restrictions on the chain segment movement.
The resins cured with rosin-derived imide-diacids exhibited significantly improved
thermal stability over those cured with the above rosin-derived anhydrides which,
demonstrated slightly lower thermal stability (approximately 20 °C lower) than the
resins cured with their petroleum-based aromatic or cycloaliphatic counterparts. In
this case, the thermal stability of epoxies cured with rosin-derived imide-diacid was
as good as that of the epoxy cured with NCPT (
Table 1.3
). It was noted that the
T
5%
for DER6224/NCPT, DER6224/RMID, and DER6224/D-RMID was 349.7, 363.1
and 355.4 °C, respectively. Also, the rosin-derived imide-diacids and their petroleum-
based analogues exhibited similar activation energies.
Table 1.3 Tensile properties and thermal stability
E
a
(kJ/mol)
T
g
(
°
C)
Strength
(MPa)
Modulus
(GPa)
T
5%
(
°
C)
Sample
NCPT/DER6224
81.68
106.5
50.2 (±3.5)
3.6 (±0.5)
349.7
RMID/DER6224
84.11
141.2
63.4 (±4.3)
4.6 (±0.3)
363.1
D-RMID/DER6224
88.07
151.8
57.9 (±3.8)
4.5 (±0.4)
355.4
Reproduced with permission from X. Liu, W. Xin and J. Zhang,
Bioresource
Technology,
2010,
101
, 2520. 2009, Elsevier [10].
