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The introduction of thermo-reversible covalent bonds in the molecular network is a recent approach to prepare self-healing polymers upon a suitable thermal trigger. Among reversible reactions, Diels-Alder (D-A) cycloaddition is an ideal candidate for the synthesis of mendable polymers, such as epoxy resins, with improved operative life. The D-A adduct, referred to as 2Ph2Epo, was synthetized and crosslinked with a mixture of aliphatic and aromatic amines. The resin formulation aimed at reaching a compromise between the mending capability of cured material and its dimensional stability at high temperatures, required during healing cycles. The latter result was achieved by mixing the adduct with commercial DGEBA monomer. The ability of the adduct to give direct D-A and reverse D-A (r D-A) has been verified by FT-IR and rheological analysis on 2Ph2Epo. Mechanical tests were performed for assessing the self-healing efficiency of the crosslinked 2Ph2Epo/DGEBA system. The multiple healing feature of the system was proved. The hybrid epoxy resin is able to recover damages, still exhibiting the pristine stiffness, while the strength of the system decreases after progressing healing cycles. POLYM. ENG. SCI., 57:674-679, 2017. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Ceramic nanoparticles, that is, SiO2, TiO2, and Al2O3 nanoparticles, with increasingly high thermal conductivity (λ), represent good candidates for improving the thermophysical properties of epoxy resins. In this study, the influence of filler addition on the thermal, mechanical, and dielectric properties were investigated by means of differential scanning calorimetry, dynamic mechanical analysis, and dielectric spectroscopy to measure λ, storage and loss moduli, dielectric permittivity, and volume resistivity. Moreover, morphological investigations by scanning electron microscopy were performed to confirm the particle dispersion into the epoxy matrix. The results show that both the elastic modulus and glass-transition temperature increased with particle content. An enhancement of λ was also observed at high filler contents because of the formation of heat conductive pathways within the matrix. The nanocomposites' relative permittivity at 50 Hz was lower, whereas the dielectric loss was slightly higher compared with that of the neat epoxy matrix. A decrease in the relative permittivity with increasing frequency, both for the unfilled epoxy resin and epoxy-nanocomposites, was observed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]