HIGH COMPRESSIVE STRENGTH PBO MICROCOMPOSITE FIBERS

PBO ORDERED POLYMER FIBERS CURRENTLY SHOW LOW COMPRESSIVE STRENGTH AS A RESULT OF MICROFIBRILLAR BUCKLING. FOSTER-MILLER PROPOSES TO SOLVE THIS PROBLEM BY PROCESSING PBO FIBERS INTO MICROCOMPOSITES, WHERE SPACES BETWEEN MICROFIBRILS ARE FILLED WITH SPECIALLY-SELECTED SECONDARY PHASE MATERIALS. PBO MICROCOMPOSITE FIBERS WILL EXCEED 200 KSI COMPRESSIVE STRENGTH FOR TWO REASONS: FIRST, PBO MICROFIBRILS WILL BE SUPPORTED AGAINST BUCKLING BY ENCAPSULATION WITHIN A MATRIX OF SECONDARY PHASE POLYMER RESIN. SECOND, PBO FIBERS WILL BECOME COATED DURING THE PROCESS WITH THIN SURFACE FILMS OF SECONDARY PHASE THAT SHRINK DURING HEAT-TREATMENT, PLACING THE FIBERS INTO RADIAL COMPRESSION AND INCREASING THEIR RESISTANCE TO BUCKLING. SECONDARY PHASE SURFACES OF PBO MICROCOMPOSITE FIBERS WILL INTERACT STRONGLY WITH THERMOPLASTIC MATRICES, PROTECT AGAINST ABRASION AND RESIST MOISTURE INCURSION AS A RESULT OF THEIR SPECIALLY-TAILORED CHEMISTRY. PHASE I OF THIS PROGRAM WILL DEMONSTRATE FEASIBILITY AND COMPARE THE EFFECTIVENESS OF SOL-GEL GLASS AND THERMOPLASTIC POLYIMIDE SECONDARY PHASES. IN PHASE II, WE WILL OPTIMIZE THE PROCESS AND EVALUATE PBO MICROCOMPOSITE FIBERS IN THERMOPLASTIC COMPOSITES.