^{Aircraft Canopies}

^{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 220°F and 300°F, respectively. Wind tunnel testing of aircraft windshield showed that the transparency surface temperatures varied from 200°F to 500°F. Therefore, high Tg canopy systems are needed to fully utilize advanced weapon systems. Conventional processing techniques for thick high Tg polymers have encountered a coloration problem.

We have developed a supermicrocellular foaming technique to process transparent samples using biphenyl endcapped poly(acrylene ether) polymers. The cell sizes of the supermicrocellular foam are smaller than the wavelength of visible light (0.4-0.7 mm) so the majority of light can be transmitted through the material. Transparent thick components can be processed since the struts are within submicron thick. Our current Phase II research focuses on optimizing the processing technique and scale up the products. Surface coatings of ATC, C742 and hard coating will then be applied. A series of SEM, optical, environmental and mechanical tests will be performed to examine the complex shape supermicrocellular foams processed. The proposed technique will result in high Tg canopies with ultra-light-weight yet considerably higher fracture toughness.

The proposed ultra-lightweight supermicrocellular foams processed from biphenyl endcapped poly(acrylene ether) are expected to have many commercial applications including aircraft canopies, windscreens, windows for commercial aircraft, outerspace structures, sensor covers, lenses, ground (such as trucks, buses, trains) and surface (ships, boats) vehicles, stores with ballistic resistant windows, viewing windows for ovens, etc.