Vinyl Ester Compatible High-Modulus Fiber System for Composite Laminates

An aqueous-based finish (sizing) was developed in Phase I to improve the carbon/vinyl ester interfacial bond. The finish is composed of a reactive coupling agent, a low viscosity vinyl ester resin, a free radical inhibitor, and a surfactant. The reactive finishes substantially improved the carbon/vinyl ester interface compared to unsized or FOE sized materials. Failure mode analysis shows that interfacial failure dominates the unsized and FOE sized materials, whereas resin cohesive failure dominates the reactive finished materials. The objective of the Phase II program is to develop an optimized aqueous emulsion finish formulation that is long lived and provides a strong, durable interface for Naval applications. Once optimized, finish compatibility with weaving and resin infusion processes will be determined, additional durability tests will be conducted, and a material property database will be constructed. A final objective is to license the finish technology to interested carbon fiber manufacturers and to conduct a life cycle cost analysis. An optimized vinyl ester compatible finish on carbon fibers will allow the Navy to fabricate cost effective lighter, stronger, stiffer, and more durable composite ships. Similar advantages will also be found in commercial composite vessels and land vehicles. These materials will also find applications in the medical, chemical processing, sporting goods, and aerospace industries.