Development of an epoxy system characterized by low water absorption and high thermomechanical performances

Abstract

Water absorption and thermomechanical properties of epoxy systems based on multifunctional dicyclopentadiene epoxy novolac resin Tactix556 cured with 4,4Ј diaminodiphenilsulfone (4,4ЈDDS) as curing agent has been studied. The base system was modified by the addition of a novel 40 : 60 PES : PEES (Polyethersulphone : Polyetheretheresulphone) amine-ended copolymer to improve toughness properties. The effect of thermoplastic addition on water adsorption was studied by gravimetric experiments. The viscoelastic properties of the resulting blend were analyzed by means of dynamic mechanical thermal analysis. The formulated systems were compared with a system based on tetraglycidyl-4,4Јdiaminodiphenylmethane resin (MY721) cured with 4,4Ј diaminodiphenilsulfone. The use of Tactix556 resin showed that water uptake values were minimized while retaining high glass transition temperatures, and toughness values were found in the same range of standard toughened matrices used for aerospace composites.

Study of cathodic protection shielding under coating disbondment on pipelines

“…The next peak is located at 4623 cm −1 , which is a combination band of the second overtone of epoxy ring stretching with the fundamental C H stretching at 2873 cm −1 [27]. The results are well consistent with others' [27][28][29][30][31][32][33][34].…”

Carbon nanotube-reinforced glass fiber epoxy composite laminates exposed to hygrothermal conditioning

“…Previous studies have reported that water exists in two forms when absorbed by the epoxy matrix, i.e., highly mobile-free water molecules (around 3600 cm -1 ) and water molecules attached to the epoxy network through hydrogen bonding (around 3300 cm -1 ) [56,57]. The FTIR spectra of conditioned GFRP composites with varying immersion times, i.e., 15, 30, and 90 days have been compared with the unaged specimen as shown in Fig.…”

Infrared Spectroscopy - Materials Science, Engineering and Technology

“…Water deteriorates thermomechanical properties (Tg, modulus, yield strength, toughness...), and adhesion, it induces chemical degradation of the network and also generates stresses because of swelling (Nogueira et al, 2001;Cotugno et al, 2001;Blanco et al, 2006;Ji et al, 2006;Xiao & Shanahan, 2008). Significant efforts have been done to elucidate the interactions of water with epoxy/amine networks and the diffusion mechanisms operating during water uptake, and many different techniques have been used: from the fast and easy gravimetry to more complex techniques such as NMR spectroscopy (Zhou & Lucas 1999) or fluorescence (Mikes et al, 2003).…”

“…The position of the bands of this molecule is particularly sensitive towards interactions like hydrogen bonding, which originates displacements towards lower wavenumbers (< 3600 cm -1 ), enabling the distinction between free water, hydrogen bonded and intramolecular hydrogen bonding (Socrates, 1994). When absorbed in epoxy resins, two types of water are found: highly mobile free water molecules (≈ 3600 cm -1 ) and water bounded to specific sites through hydrogen bonding (≈ 3300 cm -1 ) (Blanco et al, 2006;Cotugno et al, 2005;Grave et al, 1998). Signals can also be observed in the near infrared range: at 5215 cm -1 resulting from the combination of asymmetric stretching and bending and in the range 7800 -6000 cm -1 hydroxyl vibrations are also found.…”