Structure-Property Relationships in Thermoplastic Particulate- and Ceramic Whisker-Modified Epoxy Resins

Abstract

The mechanical behavior of several filler-modified epoxy resins was inves tigated. Modifications of matrix resin with thermoplastic particulates or ceramic whiskers were proposed as an alternative to rubber-toughening for improving the impact resistance of epoxy resins. Addition of 10 % by weight of untreated thermoplastic powders in an epoxy resin only slightly increased the impact energy of the epoxy resin. A reduction in flexural strength of this thermoplastic particulate-filled resin was observed. This is most likely due to poor particulate-matrix bonding. Dispersion of 10 % of ceramic whiskers in an epoxy resin improved appreciably the impact energy, flexural strength and modulus of the epoxy. The impact energy absorbed by a resin was enhanced by the approach of partic ulate/ whisker hybridization. A uniform dispersion of either particulates or whiskers in the epoxy matrix is essential to the achievement of balanced mechanical properties. Deforma tion and failure mechanisms in these composites were also examined using both SEM and instrumented impact testing.