Browsing by Author "Elizetxea, C."
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Item Analysis of the conditions to manufacture a MWCNT buckypaper/benzoxazine nanocomposite(2012-02-28) Chapartegui, M.; Barcena, J.; Irastorza, X.; Elizetxea, C.; Fernandez, M.; Santamaria, A.; POLIMEROS; EXTREMAT; COMPOSITEA study of the requirements necessary to fabricate novel MWCNT buckypaper/benzoxazine nanocomposites, based on rheological results, is presented. Best conditions to infiltrate the resin, without any diluents, in the buckypaper are selected from viscosity data obtained under time-temperature cycles. Infiltration results are analyzed using SEM microphotographs. The nanocomposite is obtained after an adequate curing process of the benzoxazine impregnated buckypaper. The mechanical and electrical properties of the nanocomposite are investigated. The obtained electrical conductivity values are several orders of magnitude larger than the values reported for conventional CNT/polymer nanocomposites.Item Composites con refuerzos naturales para aplicaciones en automoción y construcción(2010) Elizetxea, C.; Gurmendi, U.; Pijoan, T.; POLIMEROS; Tecnalia Research & InnovationThe assumption of the future exhaustion of the crude reserves world-wide and the increasing environmental concerns is leading to consider, more and more insistently, the use of regenerable raw materials for the design and development of new vehicle components. The main objective of this project consists on the evaluation of pine powder and corn powder as reinforcement for different PP resins. A compatilibization study has been defined and set-up in order to combine these two reinforcements with three different resins based on PP. A final material selection has been carried out to produce an automotive prototype part.Item In-situ polymerized continuous fiber thermoplastic composite manufactured through liquid molding processes(European Conference on Composite Materials, ECCM, 2014) De La Calle, A.; García-Arrieta, S.; Elizetxea, C.; POLIMEROSComposites with APA6 thermoplastic matrix were manufactured, reinforced with glass and carbon fabrics and, at different weights and percentages. For this purpose semi-industrial equipment specifically designed for this process was used. When the values of fiber weights and percentages where optimized, a complete mechanical characterization was carried out. For example, for PA6+GF was obtained, with modulus 30% higher than those obtained by traditional injection processes, with the same fiber volume, as well as PA6+CF composites.Item Nanocomposites in multifuctional structures for spacecraft platforms(2012) Marcos, J.; Mendizabal, M.; Elizetxea, C.; Florez, S.; Atxaga, G.; Del Olmo, E.; Tecnalia Research & Innovation; POLIMEROS; EXTREMATThe integration of functionalities as electrical, thermal, power or radiation shielding inside carrier electronic boxes, solar panels or platform structures allows reducing weight, volume, and harness for spacecraft. The multifunctional structures represent an advanced design approach for space components and subsystems. The development of such multifunctional structures aims the re-engineering traditional metallic structures by composites in space, which request to provide specific solutions for thermal conductivity, EMI-EMC, radiation shielding and integration. The use of nanomaterials as CNF and nano-adds to reinforce composite structures allows obtaining local solutions for improving electrical conductivity, thermal conductivity and radiation shielding. The paper summarises the results obtained inof three investigations conducted by Tecnalia based on carbon nanofillers for improving electro-thermal characteristics of spacecraft platform, electronic substrates and electronics boxes respectively.Item Natural fibre composites for automotive applications(2005) Rubio, A.; Elizetxea, C.; Calleja, N.; Gaztelumendi, I.; Gaballah, I.; Mishra, B.; Solozabal, R.; Tanaka, M.; POLIMEROS; Centros PRE-FUSION TECNALIA - (FORMER)The main advantage of the use of composite materials is related to their intrinsic lightweight. In this way, labour and transport costs will be strongly decreased, and the total weight of the manufactured part will be minimised. The reduction of weight implies a considerable reduction of fuel consumption with the consequent respect to the environment. Although glass fibres, as plastics, are not intrinsically harmful to the environment, some of their products can be dangerous or, at least, environment "unfriendly". The health hazards of dealing with glass fibres have been already mentioned. A second drawback of these materials regards their recyclability because it requires costly separation procedures. It is clear that from this point of view natural fibre offer more possibilities for a complete recyclability allowing the development of «eco-waste» technologies and products. This work has been carried out within the European Growth Project G5RD-CT1999-00147 "Eco-Efficient Technologies and Products based on Natural Fibre Composites-ECOFINA".Item Specific rheological and electrical features of carbon nanotube dispersions in an epoxy matrix(2010-05) Chapartegui, M.; Markaide, N.; Florez, S.; Elizetxea, C.; Fernandez, M.; Santamaría, A.; POLIMEROSThe rheological analysis of epoxy pre-polymer/MWCNT dispersions indicates that a physical network is formed. This is destroyed with an imposed shear, giving a viscoplastic and shear thinning behavior. Such destruction is not reflected in dynamic viscoelastic experiments, due to the very rapid recovery of the MWCNT network in the pre-polymer matrix. This responds to the observed lower electrical than rheological percolation threshold. Electrical conductivity results fulfill electron hopping/tunnelling mechanism, which implies a tube-tube distance close to 5. nm. However, rheological percolation requires nanotubes should touch each other, since no polymer chains are implied in the network.