Chemistry Reference
In-Depth Information
Isocyanated soybean oil (ISO) was synthesized by a two-step reaction.
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Firstly, the triglyceride was brominated at the allylic positions by a reaction
with N-bromosuccinimide, and in the second step these brominated species
were reacted with AgNCO to convert them to isocyanate-containing trigly-
cerides. About 60-70% of the bromine atoms were replaced by NCO groups
while the double bonds remained intact. ISO can be used as chain extender
for low-molecular-weight unsaturated polyesters (UPEs).
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The results show
that UPEs can be chain extended with ISO to shorten the polyesterification
time substantially without alteration of the styrene solubility or gel time of
the polyesters.
Echeverri et al.
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focused on the photo-initiated cross-linking of maleated
soybean oil (MSO) glycerides with tri- and tetrafunctional thiols without
using any other reactive diluents, such as styrene, for the synthesis of
elastomeric networks. The materials exhibited properties that resembled
elastomers with T
g
values below room temperature, and flexural moduli in
the range 240-340 MPa.
Another interesting derivative of soybean oil is conjugated soybean oil
(CSO). The conversion of vegetable oils to their conjugated counterparts is
known to produce better drying oils which can prove to be valuable sub-
stitutes for the more expensive tung and castor oils. CSO has exceptional
drying properties and the resulting coatings exhibit good solvent resist-
ance. Catalysts based on homogeneous rhodium and ruthenium as well as
platinum have been developed for the isomerization of soybean oil and
other vegetable oils under mild conditions.
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CSO can be polymerized via
free-radical co-polymerization with many other monomers including divi-
nylbenzene
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or dicyclopentadiene.
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Recently, CSO has been used to
produce new type of co-polymer with acrylonitrile and dicyclopentadiene
initiated by azobisisobutyronitrile (AIBN). The resulting thermosets were
transparent and yellow.
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Additionally, polylactic acid (PLA) was reported
by Gramlich et al.
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to be compatible for reaction with CSO. PLA modified
with the reactive end-functional group N-2-hydroxyethylmaleimide (HEMI)
was first synthesized and then reactively blended with CSO. The two
components underwent a Diels-Alder reaction with high conversion,
coupling the two immiscible components. Blends of HEMI-PLA with 5 wt%
CSO resulted in a greater than 17-fold increase in elongation-at-break
compared to the PLA homopolymer. Valverde et al.
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synthesized a range of
bio-based rubbery thermosets by the cationic co-polymerization of CSO and
styrene with 1,5-hexadiene or isoprene as a flexible cross-linker. The
moduli of the products were in the range 0.064 to 0.414 MPa and 0.243 to
0.63 MPa when using 1,5-hexadiene and isoprene as cross-linkers, re-
spectively. On the other hand, the failure strain of the products was in the
range 66 to 189% and 78 to 138% when 1,5-hexadiene and isoprene were
used as cross-linker, respectively.
Further modification of ESO can generate different derivatives by using
different chemicals.
¨
zt¨rk et al.
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synthesized radically polymerizable
triglyceride-based monomers by the reaction of ESO with 4-vinyl benzene
