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International audienceThis study aims to present structural and dielectric comparisons between two epoxy polymers. These polymers are realized by curing diglycidyl ether of bisphenol A (DGEBA) resin with either aliphatic 1,3-diaminopropane (PDA) or aromatic 4,4′-diaminodiphenyl sulfone (DDS) hardeners. They are called DGEBA/PDA and DGEBA/DDS. Several complementary techniques have been used in the present study. The structural analysis was performed using grazing incidence X-ray reflectometry. It reveals the presence of a locally ordered nanostructure in the DGEBA/DDS polymer and an amorphous character for the DGEBA/PDA one. Dielectric characterization was carried by means of dielectric relaxation spectroscopy (DRS), thermally stimulated depolarization current (TSDC) and time domain spectroscopy (TDS). DRS measurements performed over wide ranges of temperature (−80 to 160 °C) and frequency (10−1–106 Hz) showed the presence of dipolar γ and α relaxations in both polymers. Nevertheless, the interfacial Maxwell–Wagner–Sillars (MWS) relaxation appeared only in DGEBA/DDS. This can be related to the local nanostructure within this polymer, which can give rise to interfaces. Relaxation parameters were deduced from the best fits of experimental data with the Havriliak–Negami model. The calculated fragility index indicates that DGEBA/DDS is more fragile than DGEBA/PDA. The loss factor ε′′(f) was calculated from the isothermal discharging current measurements, using Hamon approximation. Thanks to this ε′′ calculation an interfacial relaxation was revealed in the frequency range of 10−3–10−1 Hz for each investigated polymer

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Bacterial contamination and biofilm formation generate severe problems in many fields.

The influence of heat treatment on the appearance and the evolution of the space charge repartition within an epoxy resin polymer material is investigated. The space charge measurements were made using the thermal step method (TSM) and the thermally stimulated depolarization currents (TSDC) method. The results obtained show the behaviour of the space charge density after heat treatment and, in particular, it can be concluded that the charges are stabilized in deep levels.© 2001 Society of Chemical Industry