Browsing by Author "Marat-Mendes, J. N."
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- Electrical properties of cork and derivatesPublication . Lança, M. C.; Neagu, E.R.; Dias, C. J.; Gil, Luís; Marat-Mendes, J. N.The electrical properties of natural cork, commercial cork agglomerates (for floor and wall covering) and a composite of cork/TetraPak® were studied. The composite was developed at LNEG/Portugal and is made of recycled cork and TetraPak® containers. Measurements of isothermal charge and discharge currents (ICC/IDC) and dielectric relaxation spectroscopy (DRS) were made. The isothermal currents characteristics and the samples electrical conductivity were investigated under different conditions (electric field, temperature and measuring atmosphere). Dielectric relaxation spectroscopy was used to quantify the changes in the permittivity with the samples conditioning. Both experimental techniques showed the strong influence of water content on the electrical properties of cork and its derivatives.
- Water content control to improve space charge storage in a cork derivativePublication . Lança, M. C.; Cunha, I.; Marques, J. P.; Neagu, E.R.; Gil, Luís; Dias, C. J.; Marat-Mendes, J. N.The influence of humidity content on the electrical and dielectric properties of a composite made from recycled TetraPak® containers and granulated cork was studied. The material components have been dried before preparation and after the composite was conditioned by keeping the samples in a dry environment (desiccator) or in an oven at high temperature (70oC in air). The differences observed in electrical properties (investigated by isothermal charge and discharge current measurement) and dielectric properties (measured using dielectric relaxation spectroscopy) show that the thermal treatment at high temperature is more efficient on removing water and slows down the re-absorption rate.