CONTROLLABLE REACTIVITY EPOXY RESINS FOR COMPOSITES REPAIRS

THIS PROJECT WILL DEVELOP RAPID CURING, HEAT RESISTANT, SOLVENTLESS NOVOLAC AND CYCLOALIPHATIC EPOXIES WITH CURING BASED ON TITANATE ESTERS AND METAL ACETYLACETONATE CATALYSTS FOR THE STRUCTURAL REPAIR OF THERMOSETTING COMPOSITES. THE CURE WILL BE CATIONIC ACID-TYPE POLYMERIZATION. THE REPAIR RESINS WILL BE BASED ON EPOXY CHEMISTRY KNOWN TO YIELD ADHESIVES AND PREPREGS FOR LONG TERM CONTINUOUS USE AT ELEVATED TEMPERATURES. ANALOGOUS MATERIALS HAVE BEEN SUCCESSFULLY USED FOR ROTATING ELECTRICAL MACHINERY SUCH AS AIRCRAFT GENERATORS IN THE F-15. NO AMINES OR CORROSIVE HALOGEN-CONTAINING COMPOUNDS WILL BE USED. THE REPAIR RESINS WILL BE BASED ON STABLE, TWO-PART SYSTEMS IN WHICH THE CATALYST PLUS EPOXY WILL BE IN ONE PART AND THE ACCELERATOR PLUS EPOXY IN THE SECOND PART. THE REACTIVITY CAN BE CONTROLLED BY THE TYPE AND AMOUNT OF THE ACCELERATOR. RHEOLOGICAL PROPERTIES CAN BE CONTROLLED WITH HEAT RESISTANT REACTIVE DILUENTS DEVELOPED FOR THE POLYMERIZATION CHEMISTRY. ADDITIONAL WORK USING DYNAMIC MECHANICAL ANALYSIS (DMA) AND DIFFERENTIAL SCANNING CALORIMETRY (DSC) WILL BE DONE AND RESULTS USED TO OPTIMIZE CURED MECHANICAL PROPERTIES OF THE REPAIR RESINS. A FINAL PHASE OF THIS PROGRAM WILL INVOLVE CONTACT WITH AIR FORCE REPRESENTATIVES TO DEVELOP THE RANGE OF APPLICATION REQUIREMENTS AND COMPOSITE SUBSTRATES FOR THIS TYPE OF REPAIR.