Chemistry Reference
In-Depth Information
with clay platelets, and the much higher modulus for clay platelets than
flexible polymer chains. However, the T
g
of the polymer, which was below
room temperature, was further decreased with increased clay loading, and
these polymers are best suited to non-structural applications.
9.9 Conclusions
The current major commercial application of EVO is as a stabilizer and
plasticizer. EVO has already shown versatility as an epoxy monomer material
resource and a variety of epoxy thermoset polymers ranging from flexible
rubbers to rigid plastics have been synthesized from different EVOs by a
number of different polymerization methods. Some of these thermoset
polymers have possessed comparable properties to their petroleum-based
counterparts and have shown promise as replacements or supplements to
commercially available epoxy monomer materials.
However, the inherently fewer reactive internal epoxy groups and flexible
carbon chain structures in EVOs have prevented their application as high-
performance thermoset polymers for structural applications. A remaining
opportunity is as a supplement for petroleum-based commercial epoxy
monomers, as matrix materials for coatings, composites or as nanocompo-
sites. The future trend in this area will be to increase the percentage of
bio-based content whilst optimizing overall performance through structure-
property studies. Developing new, VO-derived epoxy monomers with higher
reactivity and oxirane functionality will provide an opportunity to expand the
use of EVOs as green materials. As novel VO-based epoxy resins, EGSs have
shown improved properties than other EVO structures but only when the
saturated content is reduced. They are currently at an experimental stage
towards commercialization.
The versatility of epoxy formulations not only depends on the epoxy
monomer, but also on the combined effect of the curing agent, co-monomer,
and polymerization conditions. Effective EVO curing systems with short poly-
merization times and lower curing temperatures are highly desired. EVO will
be of continued interest with regard to environmental and renewable/
sustainable efforts through industrial applications, but only if the materials
meet customer performance requirements in terms of reactivity, compatibility
and polymer mechanical, thermal, and environmental stability properties with
minimal or no tradeoffs, and at a competitive cost. This chapter has sum-
marized the issues of reactivity, compatibility, and properties as a function
of EVO chemical structure. The continuing challenge is to create new cost-
effective EVO-derived structures that improve upon existing performance levels.
References
1. H. Q. Pham and M. J. Marks, in Encyclopedia of Polymer Science Tech-
nology, ed. H. F. Mark, John Wiley & Sons, 2004, vol. 9, p. 678.
