Chemistry Reference
In-Depth Information
increase in thermostability was observed due to the incorporation of flexible
fatty chains into the rigid hydrophenanthrene units in the rosins. When
applied in a PU adhesive as a tackifier, an increase in the amount of tung oil
in GTRs led to an initial increase and then a decrease in both the miscibility
of the GTR with PU and the T-peel strength of the adhesives. The elongation-
at-break of the films increased monotonically, but their tensile strengths
initially increased and then decreased with increasing amounts of tung oil in
the GTRs.
5.5 Other Plant Oils
Corn oil is one of the cheapest commercially available vegetable oils and is
mainly used in food and livestock feed.
8
It contains an average number of
double bonds of 4.1 per triglyceride, which can be involved directly in the
synthesis of polymers. Epoxidation of corn oil is also interesting. Sun et al.
135
reported an enzymatic epoxidation of corn oil using hydrogen peroxide as an
oxygen donor and stearic acid as an active oxygen carrier in the presence of
Novozym 435. Epoxidized corn oil is also useful in renewable, bio-degradable
and non-toxic lubricants, polymer stabilizers, and intermediates. Epoxidation
is also an interesting modification of other plant oils like linseed oil. Epox-
idized linseed oil can be used as a bio-based plasticizer, a possible substitute
for phthalate in PVC.
136
Moreover, a 99.5% bio-derived highly flexible trans-
parent film with significant water resistance was obtained from epoxidized
linseed oil with a bio-based diacid cross-linker.
137
Euphorbia oil on the other
hand, is the only plant oil that possesses epoxy groups of its own. Therefore,
direct polymerization of euphorbia oil by ROP was carried out by Liu et al.
138
in liquid CO
2
, catalyzed by BF
3
OEt
2
. The resulting polymers were cross-
linked with T
g
values in the range
15.0 to
22.7 1C. Palaskar et al.
139
syn-
thesized a series of sunflower-oil-based polyols as PU precursors. While
Alemdar et al.
140
developed a sunflower-oil-based macro-initiator, which was
then styrenated using reversible addition-fragmentation chain transfer poly-
merization (RAFT) in the presence of phenacyl morpholine dithiocarbamate
(PMDC) as a chain-transfer agent. The resulting material gave transparent
films with good film properties. Kong et al.
141
synthesized two novel bio-based
poly(ether ester) polyols with high functionality and low viscosity from canola
oil by a simple, three-step reaction including epoxidation, hydroxylation and
transesterification. These canola-oil-based polyols were used for the pro-
duction of PUs with commercial petrochemical-derived diisocyanate. This
work established the production of polyols and their corresponding PUs from
vegetable oil starting materials with the glycerol backbone being removed
explicitly during the polyol synthesis reaction.
5.6 Conclusions
From the point of view of sustainable development, the utilization of plant
oils for polymer synthesis is promising, and much progress has been made
