Sealants – Gap Fillers

Topic #: AF1998-193
Sponsor: AF ML
Status:Phase II completed
Need: Durable and easy to use gap filler for LO technologies.
Operational Gap: Current systems are two component making it more difficult to use.
Specifications:Minimize density. Quick cure

A durable one component conductive gap filler/sealant is proposed as a new material for aircraft the employ low observable (LO) technologies. This material will combine the durability of a polysulfide with the ease of use of a one component system. No mixing will be required and waste will be minimized. Conductive fillers will be investigated for incorporation into the matrix resins. Various conductive loading levels will be considered. In the proposed heat activated system, the gap-filler material is briefly heated prior to application. This initial heat activation liberates a latent curing agent, which will remain active after delivery to the substrate. Cure will continue after application to the substrate, and complete cure will be achieved in approximately 5 minutes to 24 hours depending on catalyst concentration. Density of the gap-fillers will be minimized in order to achieve weight savings on aircraft. Additionally, the functionality of the proposed system is expected to have improved bond strength to aluminum and epoxy/carbon fiber composites. Characterization of conductivity and radar observability will be determined for the candidate products.