The objective of this proposal is to demonstrate the feasibility of a halogen free nanocomposite vinyl ester system that will provide low flammability composites. The nanocomposite system proposed will be based on commercially available vinyl ester resins and thus should not result in a significant increase to raw material costs. Layered silicate based nanocomposites are a relatively new class of materials with properties that are unattainable with conventional microscale reinforcements. In fact, even at low concentrations layered silicates have been shown to provide an increase in modulus, heat distortion temperature, impact strength and fire retardance. One of the key drawbacks in these systems is a dramatic increase in viscosity when the silicate is well dispersed. This viscosity increase negates the ease of processability for void-free composites that is key to the utilization of vinyl esters in many composite applications. For this reason, one main thrust of this proposal will be to introduce the dispersed silicate reinforcements into the vinyl ester in such a way as to preserve the ease of processability.Vinyl ester resins are important matrix resins for thermoset polymer matrix composites. The low room temperature viscosities of the vinyl ester - styrene mixtures coupled with tailorable cure schedules, low cost and excellent mechanical properties make them prime candidates for composites in transportation, infrastructure and marine applications. Flame retardant vinyl ester composites are currently utilized by the Navy as well as in many private industry products. In fact, of the 60 million lbs. of vinyl ester sold into the North American market in 2000, 10% (6 million lbs) were flame retardant with an annual growth rate of 4%.2 The current flame retardant technology is dependant on brominated resins. The bromine content provides for a lower heat release rate, however the smoke generation is high and the carbon monoxide generation is even higher than in non-halogenated resins. Another disadvantage of the brominated systems is that the smoke generated during combustion could be both toxic and corrosive. For these reasons, although brominated vinyl esters are currently the best technology available, improvements are still desired. Our proposed non-halogenated, processable nanocomposite vinyl ester resin will provide a significant improvement to the current state of the art.
Keywords: Composite, RTM, VARTM, Pultrusion, Nanocomposite, silicate, Flame retardant, vinyl ester
