Development of a toughened DGEBS/DDS system toward improved thermal and mechanical properties by the addition of a tetrafunctional epoxy resin and a novel thermoplastic

It was the object of the present article todiscuss the effect of the addition of a tetrafunctional resin,namely, tetraglycidyl-4,4-diaminodiphenylmethane (TGDDM),and of a novel 40:60 polyethersulfone:polyetherethersulfone(PES:PEES) copolymer on a blend constituted bya difunctional resin, diglycidyl ether of bisphenol S(DGEBS), and an aromatic ammine, 4,4-diaminodiphenylsulfone(4,4DDS). The formulated blends were fully characterizedin terms of the morphology and the viscoelasticand mechanical properties. The modification by the tetrafunctionalresin was proved to be a useful means to improvethe glass transition temperature and, therefore, to widen therange of the working temperature. The addition of the novelcopolymer resulted in a marked increase in toughness withoutnegatively affecting the thermal and elastic properties ofthe blend. TEM analysis, despite the high amount of thermoplasticused, showed a homogeneous morphology thatwould lead to the conclusion of the existence of a full-IPNnetwork. Moisture-uptake experiments were conductedboth on the blend and on the resins on their own. It wasshown that the combination of the difunctional resin withthe tetrafunctional led to a decrease of the percent of thewater absorbed