TOUGHENING OF EPOXY-RESINS WITH THERMOPLASTICS .2. TETRAFUNCTIONAL EPOXY-RESIN POLYETHERIMIDE BLENDS

A series of blends has been prepared by adding a polyetherimide (PEI), in varying proportions, to a tetrafunctional epoxy resin, tetraglycidyldiaminodiphenylmethane (TGDDM), cured with 4,4'-diaminodiphenylsulphone (DDS). All the materials exhibited two-phase morphologies which were characterised by dynamic mechanical thermal analysis and scanning electron microscopy. Addition of the thermoplastic gave a modest improvement in fracture properties (K1C and G1C), as determined by three-point bending experiments, although no obvious correlation with the marked morphological changes was observed.