Papers by Keyword: Cork

Abstract: A carbon molecular sieve for the purification of a gas mixtures containing O2, N2 and CO2, CH4 was produced from a waste granulated PET by means of a single carbonisation step at 973 K. Activated carbon materials presenting good adsorption capacity and some selectivity for O2/N2 and CO2/CH4 were prepared from granulated PET and cork oak with pore mouth narrowing using CVD from benzene. The diffusion coefficients of O2, N2, CO2 and CH4 in these materials were calculated and are comparable to published values determined on Takeda 3A and on a carbon molecular sieve prepared from PET textile fibres by means of carbonisation and subsequent CVD with benzene. However, the selectivities were not quite as good as those given by Takeda 3A. However, taking into account that this is a first attempt at producing CMS from PET, the results are encouraging, and it is to be expected that further development of the experimental procedure will result in new materials with improved performance.

Abstract: This study presents an experimental characterization of cork storage modulus used to model the vibration response of bars built using alternate layers of cork and steel. In the experimental setup, the specimen was suspended from a fixed support by two thin lines while a shaker was suspended from a mobile support by metallic chains. The shaker was connected to the bar specimen through a force transducer imposing a dynamical deformation that propagates through the specimen. An accelerometer in the opposite extremity of the bar measures the corresponding vibration response and the cork storage modulus is then obtained from the first peak of this frequency response. The proposed methodology successfully characterized the storage modulus of the cork material used in the multilaminated periodic bars. The results obtained illustrate a satisfactory correlation between

Abstract: Activated carbons are materials extensively used to remove a variety of pollutants in different media. The porous structure, the surface chemistry and the type of adsorptive determine the potential of activated carbons as an adsorbent material. However, in a more global perspective it is necessary to consider other factors such as the economical viability of production and reuse. This last factor depends on the capacity of regeneration of the activated carbons after each application. Following this guideline, the objective of this work was to evaluate the capacity of regeneration of some specific activated carbons prepared from cork oak wastes, used in the adsorption of phenolic compounds in the liquid phase. Simultaneously, the performance of our carbons are compared with the behaviour of a commercial carbon (Norit SX plus). The experimental procedure consists in the adsorption of one phenolic compound, followed by the regeneration of the adsorbent, succeeding a series of adsorption/regeneration processes. The methods of regeneration used were simple washing with distilled water under magnetic stirring, washing with ultrasound and thermal regeneration under inert atmosphere. The performance of the activated carbons was strongly dependent on their nature and the regeneration method applied.

Abstract: Activated carbons have been prepared by physical activation in CO2 of commercial byproduct kraft lignin (as received, after de-ashing and after impregnation with NaCl) and natural cork. The results obtained show that the presence of natural inorganic impurities increases the reactivity of cork and lignin significantly and also results in limiting values for the micropore volume and in widening of the micropore size. Pure de-ashed lignin is exceptionally non-reactive but allows microporous activated carbons to be obtained which have very narrow micropore widths of ~0.5-0.6nm. When the de-ashed lignin is impregnated with NaCl similar micropore volumes and widths can be obtained but in a considerably shorter time (~30min instead of ~8h) which would result in a considerable energy saving and is therefore a promising procedure for the production of microporous activated carbons from low-cost kraft lignin.

Abstract: Lately the electrical and dielectric properties of cork and some cork-based materials (commercial and non-commercial) have been studied in order to understand their ability to store electrical charge. The main problem found so far is related to the water content in cork, only of a few % weight, but large enough to influence greatly the conductivity of cork and, consequently, the charge storage capability. To overcome this problem cork has been combined with hydrophobic materials. In this work a commercial wax (paraffin wax) was used to produce a cork/paraffin composite by hot pressing. After milled and mixed natural cork, TetraPak® containers waste and paraffin were pressed to make plaques of a new composite. Different concentrations of cork, TetraPak® and paraffin, different granules size, different temperature and pressure were used to produce the samples. The electrical properties of the new composite were measured by the isothermal charging and discharging current method and the results compared to previously ones obtained for natural cork and other derivative products. The new composite has shown to have lower conductivity than the commercial agglomerate, which makes it a better material for charge storage.

Abstract: Cork is a natural cellular material which has been used for centuries, in natural and agglomerate forms, mainly for applications related to the wine, the automotive and the construction industries. It is a very durable and ecological material, used for thermal, acoustic and vibrating insulation as well as packaging, among others. This paper highlights some of the aspects of a topic of great interest, not much explored yet, which consists of the study of the dynamic mechanical behaviour of innovative structures incorporating cork, dedicated to energy-absorption. Experimental and numerical tests, using the finite element method software LS-DYNA™, were performed in order to evaluate the effects of filling agglomerate cork inside thin-walled metallic tubes, with variable geometries and thicknesses, impacted uniaxially at quasi-static and high strain rates. Some relevant comparisons were carried out and the results obtained allowed concluding that cork might be a viable energy-absorbing material for application in some metallic structures subjected to impact loadings.

Abstract: Electrical properties of natural cork, commercial cork agglomerates (for floor and wall coverings) and a recently developed composite of cork/TetraPak® were studied. Measurements of isothermal charge and discharge currents were made for natural cork samples in different directions (axial, radial and tangential cuts). The isothermal current characteristics and the samples conductivity were investigated under different conditions (electric field, temperature and environmental conditions: in air at ambient relative humidity (RH), dry air and vacuum), also the samples could be or not conditioned (dried in vacuum or in a P2O5 atmosphere at room temperature). From these results the influence of water on the electrical properties of natural cork could be seen. In order to compare the three different cork materials a preliminary study was made. Isothermal charge and discharge currents and conductivity after 1h charging were measured and compared for different electric fields and temperature in air at ambient RH.