Chemistry Reference
In-Depth Information
Table 8.4 Viscosity (V
s
), gel time (t
gel
), and linear shrinkage (l
s
) of the
neat UPR, COPERMA, and UPR/COPERMA resins.
Sample
V
s
/mPa
s
t
gel
/min
l
s
/%
UPR
440
7-8
0.52
0.09
COPERMA
2680
430
—
UPR/COPERMA5
570
8-9
0.41
0.07
UPR/COPERMA10
680
9-10
0.31
0.06
UPR/COPERMA15
810
10-11
0.12
0.04
UPR/COPERMA20
950
11-12
0
On the other hand, the COPERMA resin did not generate rigid bio-plastics
using the curing procedure for general-purpose UPRs, as shown in the
experimental section. Therefore, it will be valuable to partially substitute
petroleum-based UPRs to create blends with this relatively new bio-resin.
8.3.4.1 Dynamic Mechanical Analysis
The DMA technique was employed to investigate the thermomechanical
properties of the obtained bio-materials. The results are shown in
Figure 8.20 and Table 8.5. The storage moduli at 35 1C of UPR/COPERMA5
and UPR/COPERMA10 were higher than that of neat UPR, while it was the
opposite for UPR/COPERMA15 and UPR/COPERMA20. A maximum increase
of 17.6% was observed for UPR/COPERMA5. The n
e
and M
c
values were
calculated according to eqn (4), and are presented in Table 8.5. The values of
E
0
used for the calculations were taken at approximately 40 1C above the T
g
in
these materials. The density of the UPR/COPERMA resins ranged from 1.099
to 1.103 g cm
3
. The n
e
values were in the range of 2270-2570 mol m
3
,
which corresponds to molar masses of 429-484 g mol
1
. With the addition
of COPERMA into UPR, the n
e
increased slightly, which was quite
different from the reduction caused by the incorporation of other reported
bio-additives.
11,12
This n
e
increase may lead to a pronounced effect on
the mechanical properties of the obtained polymers. The temperature
dependence of tan d is shown in Figure 8.20(b). The tan d curves showed
only a single T
g
, suggesting that phase separation in the obtained
UPR/COPERMA resins is not obvious. T
g
was determined from the peak of
tan d, as illustrated in Table 8.5. A slight increase was observed for
the bio-based resins. The maximum increase of about 3.4 1C was seen
for UPR/COPERMA15, which can be attributed to it having the maximum n
e
increase.
8.3.4.2 Thermogravimetric Analysis
Figure 8.21 shows TGA thermograms and their derivative curves for the
cured neat UPR and UPR/COPERMA polymer matrices. It can be seen that
