High-Temperature Integral Tank Sealant

The Air Force has long utilized the integral fuel tank concept in the design of the airframes for its aircraft. These airframe designs require that the tanks have a sealant that will maintain the integrity of these structures under a wide range of environmental conditions. A particular need has been identified for sealants that will perform well in long-term service at air temperatures of 350 degrees Fahrenheit and fuel temperatures of 250 degrees Fahrenheit. Sealant materials that have been developed to date include fluoropolymer types that have poor adhesion and application properties and polythioether types that do not have the thermal stability required to meet the new high temperature requirements. TRI/Austin is developing a polymer system for sealants which offers the high temperature properties of the fluoropolymers with the good adhesion and application properties of the polythioethers. The polymer system developed during the Phase I research has demonstrated the feasibility of producing the desired material combination and the performance properties of the sealants prepared using this polymer indicate that improved high temperature fuel resistance properties can be achieved.