Under an Air Force Research Laboratory Small Business Innovation Research (SBIR) Phase II contract, TRI/Austin has developed a resin system that cures rapidly using UV light.
Delays in repairing battle-damaged aircraft can have a significant impact on the quest for air domination. A method to quickly repair the aircraft in the field provides the opportunity to fly additional operational sorties and further contribute to wartime objectives. Traditional resins used for aircraft repair are difficult to deploy in the field because of the requirement for a high temperature thermal cure. Airframe structures act as heat sinks, making it difficult to obtain uniform temperature profiles and properties. Thermal cure temperatures can be as high as 150degC and require as much as 24 hours for cure. Some resins also require low-temperature storage, which may not be available in the field.
TRI/Austin material scientists, John W. Bulluck and Brad A. Rix, were awarded U.S Patent No. 7,144,544 for the development of a UV light curable formulation for repairing composite materials. “We chose an acrylate based chemistry because of fast reaction rates and the ability to meet demanding mechanical and thermal property requirements of the application”, noted John Bulluck, the Materials Development Division Manager. “We were able to achieve glass transition temperatures higher than 155oC, which surpasses some military-approved thermally cured epoxies. Cure times are also quite fast - on the order of minutes instead of hours.” The resin can be used with UV transparent fibres made of quartz or glass.
TRI/Austin teamed with Abaris Training, which specializes in the repair of advanced composites, in order to develop easy-to-use field procedures. Michael J. Hoke, president of Abaris Training, indicated that “the chief advantages of this resin system include the ability to quickly patch the skin without applying heat and to repair large areas without exotherm problems.”
The patent was assigned to TRI/Austin, Inc’s. parent company, Texas Research International, Inc.
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