Processing of High Tg Polymers for Aircraft Canopies using a Supermicrocellular Foaming Technique

Current fighter canopy systems are fabricated using acrylics and polycarbonates which have low use temperatures, up to 220F and 300F, respectively. Wind tunnel testing of aircraft windshield showed that the transparency surface temperatures varied from 200F to 500F. Therefore, high Tg canopy systems are needed to fully utilize advanced weapon systems. Conventional processing techniques for high Tg polymers have encountered a coloration problem as the specimen become thicker. We propose a supermicrocellular foaming technique using the principle thermodynamic instability to process aircraft canopy system. The cell size of a supermicrocellular foram (submicrons) is smaller than the wavelength of visible light (0.4-0.7) so the majority of light will be transmitted through the material without being deflected.