Chemistry Reference
In-Depth Information
UPR/COPERMA resins became rougher as the COPERMA-resin content in-
creased from 10 to 20 wt%.
The increased roughness suggests that all constituents of UPR and
COPERMA are not homogeneously mixed at the molecular level, which may
result from the incompatibility of the petroleum-based UPR and COPERMA,
probably generated by the large difference in acid group numbers. As
mentioned above, the increase of cross-link density would lead to a de-
creasing toughness of the resulting thermosets, while a rougher surface
corresponds to the dissipation of more impact energy, due to shear de-
formation during crack propagation.
10,11,14,15,18,23
Hence, although the
slight increase in cross-link density (Table 8.5) decreases the toughness of
the UPR/COPERMA polymer matrix a little bit, the increase in roughness
leads to a pronounced toughening effect and compensates for the loss of
toughness caused by the increase of n
e
. When the roughness effect over-
whelms the n
e
effect on toughness, the impact strength of UPR/COPERMA
resin begins to increase. This is the reason why an increase in toughness was
observed from UPR/COPERMA10 to UPR/COPERMA20.
All of the samples tested were transparent or quasi-transparent from the
visual inspection of the impact test samples [Figure 8.24(f)], indicating no
obvious phase separation of ingredients in the material. This agreed well
with the DMA results. When the content of COPERMA resin was increased
from 0 to 5 wt%, the samples were transparent and almost colorless. How-
ever, as the content of COPERMA resin was increased from 10 to 20 wt%, the
samples were not as transparent as the pure UPR and UPR/COPERMA5 and
the color of them changed to light yellow. These results agree with the SEM
observations of surface roughness changes of the UPR/COPERMA samples.
8.4 Conclusions
Currently the development of oil-based UPRs from natural oils or their
derivates is widely advocated due to the requirements of ''green'' chemistry
all around the world. In this chapter, novel oil-based UPRs including
TOPERMA resin, DCPD-UPR-TO resin, and UPR/COPERMA blends have been
successfully fabricated by functionalizing plant oil triglycerides or blending
with petroleum-based UPRs. These materials show promise for applications
as engineering plastics and in composite fields. In the development of
DCPD-UPR-TO polymers, the method employed was not only a simple
blending method, but also involved the chemical modification of UPE via a
Diels-Alder reaction between C
ΒΌ
C bonds on polyester and TO conjugated
trienes. This method avoids the occurrence of phase separation in the re-
sultant polymer matrix, up to a TO content of 7.4 wt%. Moreover, by the
incorporation of highly functionalized COPERMA into UPR, we obtained a
bio-based UPR blend with physical, mechanical, and thermal properties that
were comparable to, or even slightly better than, those of neat UPR. There-
fore, blending a high-functionality UE monomer with petroleum-based UPR
is an effective approach to fabricate a high-performance bio-based UPR for
