The mechanical properties of continuous graphite fiber reinforced com posites containing filler modified epoxy matrix have been investigated. Modification of epoxy resin with either thermoplastic particulates or inorganic whiskers was proposed as an alternative to rubber-toughening for improving the impact resistance of fibrous compos ites. Addition of 5-15% by weight of thermoplastic powders in an epoxy resin increased the impact energy of the graphite-epoxy composites without sacrificing composite modu lus and strength properties. In the case of hybrid composites containing PVDF or PEEK thermoplastic particulates, the particle-matrix bonding was found to be relatively poor. This poor particle/matrix bonding did not appear to be detrimental to the impact energy absorbing capability of the fibrous composites. A uniform dispersion of either particulates or whiskers in the epoxy matrix was found to be essential to the achievement of balanced mechanical properties The failure mechanisms in various matrix-modified composites have also been evaluated based on their fracture morphologies as well as impact and flex ural properties.
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