Microstructure and dielectric behaviour of carbon nanofibers-alumina nanocomposites

Abstract

Resumen del póster presentado al 8th International Workshop on Interfaces: "At the boundary between natural and synthetic materials", celebrado en Santiago de Compostela (España) del 26 de junio al 1 de julio de 2011.Carbon nanofibers-Alumina (CNF-Al2O3) nanocomposites are interesting materials because it is possible to design materials with a very wide range of the ac conductivity values. Depending on the amount of CNF the ac conductiviy of these materials ranges bemeen 10(-4) and 10(-14) s/cm and, therefore, they may flnd applications as dissipative materials. In this study, CNF-Al2O3 nanocomposites, in which CNF content was varied between 1 and 4% volume, were synthesized following processing routes: in one case the CNF were ball-milled before mixing with alumina and in the ofher case raw CUNF were used. Depending on thr CNF procesing different microstructures were obtained. In the composites with ball-milled CNF tke scanning electron microscopy images show a homogeneous dispersion of the CNF while in be composites with raw CNF the nanofibers ane highly agglomerated. These differences Ln the microstructure confer the composites dfferent behaviours of ac conductivity: with raw CNF it is not possible to get a fine-tuning of the ac conductivity and the composites present large steps in ac conductivity values in samples with different amount of CNF. On the other hand, the ball-milled CNF composites show reproducible and well-controlled ac conductivity values in a small range, between 8.10(-7) y 9.10(-8) s/cm, at frequencies below 1Hz. The present work reports on the importance of the processing of CNF in the microstructure and the ac conductivity behaviour of the final nanocomposite.Peer Reviewe