New Thermoplastic Elastomer Matrix Resins for Advanced Aircraft Sealants

Military aircraft require conductive sealants around fuel tanks and structural gaps to prevent fuel leaks, water ingress, corrosion and to provide electrical continuity. Limitations of conventional polyether and polysulfide-based sealants include: the slowness of cure below room temperature, solvent thinning and degradation at elevated temperature. A novel gap sealant based on conductive particle-filled, highly flexibilized thermoplastic elastomers (TPE) is proposed for this application. The rigid blocks have high polarity for fuel resistance, high temperature stability and metallic particle compatibility. The flexible soft blocks are selected from rubber precursors having inherent resistance to aviation fuel and glass transition temperatures below the proposed lower use temperature range. The novelty of the approach would stem from the mode of chemically linking the TPE components to achieve the desired property profile. The proposed sealant system should effectively protect aircraft structures from environmental damage and exhibit high electrical conductivity. TPE's will be formulated with electrically conductive fillers and rheological modifiers and tested for adhesion to aluminum and composites, electrical conductivity, fuel and water barrier properties, resistance to thermal and chemical degradation, and corrosion inhibiting properties. The physical performance will be compared to commercial sealants meeting MIL-S-81733.