Nontoxic Resins Advance Aerospace Manufacturing
- Sunday, 01 November 2009
Originating Technology/NASA Contribution
A small pile of PETI-330 resinous powder PETI-330 is the first resin created specifically for high-temperature composites formed with resin transfer molding and resin infusion. Offering processability, toughness, and high-temperature performance, the resin has a low-melt viscosity and, when cured, a high glass transition temperature.
In the late 1980s, scientists and engineers at Langley Research Center began to develop technology for future commercial supersonic air travel, which could reduce travel time across the Pacific or Atlantic Ocean to less than half the time possible with modern subsonic jets. Although British Airways and Air France offered high-speed travel across the Atlantic on the Aérospatiale-BAC Concorde aircraft at speeds of about 1,350 miles per hour (Mach 2.05, or 2.05 times the speed of sound, depending on altitude), NASA hoped to develop quieter, more fuel-efficient, faster supersonic jets that would travel at Mach 2.4 and carry up to 300 passengers, 3 times the number on Concorde. Supported by a team of U.S. aerospace companies, the Agency’s High-Speed Research (HSR) program began to explore the possibility of making these supersonic passenger jets a reality.
For the new jets, the HSR program needed a structural material with higher temperature capability than Concorde’s aluminum alloy, which would not tolerate the aerodynamic heating at higher altitudes at sustained speeds above Mach 2.2. Because wind friction can cause the outer surface of an aircraft to reach a temperature of 177 °C (350 °F) at Mach 2.4, the HSR team investigated new materials that retained their mechanical integrity at 177 °C for 60,000 hours—the anticipated service life of a commercial supersonic aircraft.
Chemicals manufacturer Ube Industries Ltd., based in Ube City, Japan, has its North American headquarters, Ube America Inc., in New York. At the same time that Ube was seeking applications for a unique monomer (a small molecule that can be used as a building block for advanced high-performance polymers), Langley scientists Dr. John Connell, Paul Hergenrother (now retired), and Dr. Joseph G. Smith, Jr. were investigating these chemical building blocks that could impart specific physical, thermal, and mechanical properties into high-temperature polymers for the HSR program. Ultimately, NASA was seeking a partner in private industry that could provide materials and manufacturing capability for a high-temperature resin that met the property requirements for structural applications on supersonic aircraft. A colleague from the Japanese Aerospace Exploration Agency (JAXA), Dr. Rikio Yokota, introduced the two teams, and they formed an informal collaboration in which Ube provided a unique monomer to the Langley researchers for chemical evaluation. “We used Ube’s monomer to prepare over 50 resin formulations, measured properties, and honed in on the best performing material,” says Connell.
The monomer was a byproduct from the synthesis of another chemical used in the microelectronics industry. However, Connell explains, “This unique monomer was difficult and expensive to synthesize directly, so we collaborated with Ube to obtain the monomer and to investigate the effect of this monomer on polyimide matrix resins.” Although the HSR program was phased out in 1999, the Agency continued development with Connell’s team at Langley, who recognized that this material might fill a need in aerospace manufacturing for a high-temperature resin that could be easily processed.