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

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Abstract
It was the object of the present article to discuss 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 by a difunctional resin, diglycidyl ether of bisphenol S (DGEBS), and an aromatic ammine, 4,4′‐diaminodiphenylsulfone (4,4′DDS). The formulated blends were fully characterized in terms of the morphology and the viscoelastic and mechanical properties. The modification by the tetrafunctional resin was proved to be a useful means to improve the glass transition temperature and, therefore, to widen the range of the working temperature. The addition of the novel copolymer resulted in a marked increase in toughness without negatively affecting the thermal and elastic properties of the blend. TEM analysis, despite the high amount of thermoplastic used, showed a homogeneous morphology that would lead to the conclusion of the existence of a full‐IPN network. Moisture‐uptake experiments were conducted both on the blend and on the resins on their own. It was shown that the combination of the difunctional resin with the tetrafunctional led to a decrease of the percent of the water absorbed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 268–273, 2003