SHELF-STABLE LOW TEMPERATURE CURE EPOXY FILMADHESIVE FOR ON-AIRCRAFT BONDED REPAIR

摘要

The objective of this Phase II SBIR program was to develop and test a prototype shelf-stablernaerospace epoxy film adhesive (SSEFA) to meet MIL-A-25463 requirements following storagernat temperatures up to 32℃ (90℉) for 12 months with brief temperature spikes up to 49℃rn(120℉). Following cure at 94℃ (200℉), the SSEFA must exhibit equivalent mechanicalrnproperties to current MIL-SPEC qualified film adhesives. Two approaches toward achievingrnthis objective were pursued; namely, using a thermally-triggered "smart catalyst" that reacts onlyrnupon heating to a predetermined "trigger" temperature and encapsulation of epoxy cure catalystrnwithin cross-linked gelatin microcapsules which is released upon demand via crushing orrnthermal release mechanisms. Microencapsulated epoxy resin cure accelerator was successfullyrnincorporated into prototype SSEFA test samples using commercial film adhesive productionrnequipment and these samples were characterized for shelf-stability at various temperatures andrnmechanical properties before and after cure at 49℃ (120℉) and 121℃ (250℉). The results ofrnour efforts to develop and improve the SSEFA will be described.