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Thermomechanical and morphological properties of blends of epoxy monomers and hydroxyl and epoxy functionalized hyperbranched polyesters have been studied. Different properties of the blends were found by changing the cure cycles (a precure step followed by a postcure at higher temperature). All the blends showed phase separation with a particulate morphology. Through the addition of the hydroxyl-ended modifiers, rather than the epoxy-ended, an increase of the viscosity and of the reactivity of the uncured blends was obtained. The blends containing the epoxy functionalized polymer showed some liquid-liquid transitions in the rheological traces, probably because of the phase separation phenomena. POLYM. ENG. SCI., 46:1502-1511, 2006.

It was the object of the present article to discuss the effect of the addition of a tetrafunctional resin, namely, tetraglycidyl-4,4Ј-diaminodiphenylmethane (TG-DDM), 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, 4,4Ј-diaminodiphenylsulfone (4,4ЈDDS). 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.

Abstract:In this article we present the results of a study on the properties of a blend containing a 40:60 amine-ended copolymer, poly(ether sulfone)-poly(ether ether sulfone), with a system composed of diglycidyl ether of biphenol S and 4,4Ј-diaminodiphenyl sulfone (4,4Ј-DDS). Five formulations, which varied in amounts of modifier, were characterized through dynamic thermal mechanical analysis and fracture mechanics studies. The morphology of the blends was studied by transmission electron microscopy (TEM). The addition of thermoplastics enhanced the toughness of the system, resulting in an increase in the glass-transition temperature as a function of the amount of thermoplastics. No phase-separated morphology was detected by TEM analysis, leading to the conclusion that the formation of a homogeneous semi-IPN network occurred between the thermoplastics and the thermoset.

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