Browsing by Keyword "A. Nanocomposites"
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Item Microstructural study of vapour grown carbon nanofibre/copper composites(2008-05) Barcena, Jorge; Maudes, Jon; Coleto, Javier; Baldonedo, Juan L.; Gomez de Salazar, Jose M.; Tecnalia Research & Innovation; PRINTEX; MercadoVapour grown carbon nanofibres from different manufacturers have been incorporated into copper in order to obtain metal-matrix composites with high volume fraction of reinforcement. The manufacturing route involved copper deposition by the electroless plating technique and further hot-pressing of the composite powders. A material with porosity less than 1% was obtained. The microstructure was investigated by scanning electron microscopy and transmission electron microscopy. After hot-pressing the carbon nanofibres were seen to be homogeneously dispersed in the matrix and showed a random planar distribution. Despite the poor wetting between copper and carbon, the Cu/C interface formed was continuous. The matrix was composed of grains in the nanometric range, suggesting that the nanofibres act as grain growth inhibitors.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.