Study On The Preparation Of Vopor-grown Carbon Nanofibers And Properties Of Carbon Nanofibers Reinforced Epoxy Resin Composites

For the purposes of mass production and application of carbon nanofibers (CNFs), the preparation process of CNFs has been investigated. The morphology, microstructure of CNFs have been discussed. The effects of CNFs as fillers into polymer matrix on its mechanical and electrically performance have also been preliminarily studied.Pure CNFs with uniform diameter distribution have been successfully prepared by chemical vapor deposition method, using benzene as carbon source, ferrocene as catalyst precursor, hydrogen as carrier gas, and sulfur-containing compound (thiophene) as growth promoter. The chemical vapor deposition method which allows three-dimensional dispersion of catalyst particles and in which the catalyst introduced can easily be controlled, is thought to be promising as an industrial process for growing CNFs.The products generally have two microscopical forms —filmy and bulk forms. Through SEM and TEM observations, it is found that the former one contain mainly fasciculies of multi-walled and even single-walled carbon nanotubes with diameter of 2-50nm, while the later one are mainly pure nanofibers with diameter of 50-100nm. This result is also been ascertained by Raman spectrometry. It can be proposed that, if the reaction conditions are optimized to prohibit the growth of outer layer pyrocarbon, then the pure and high quality multi-walled carbon nanotubes with diameter of 5-15nm and even single-walled carbon nanotubes can be prepared by the present chemical vapor deposition method.It is experimentally found that four main factors, pyrogenation temperature, volatility of catalyzer, fraction of thiophene and hydrogen flux affect the yield and diameter of CNFs. Sulfur has a dramatic effect on the growth of CNFs, and the addition of small amount of S into the reaction can cause a higher yield of CNFs and obtaining a much more uniform diameter distribution. Preferable process parameters are decided with the endeavor of obtaining high yields of CNFs with controllable diameter.Carbon nanofibers are generally used as reinforcement and electrically conductive filler in polymer composites. Through experiments, it is also found that the mechanical performance and electrical conductivity of epoxy polymer has been dramatically improved by adding additional carbon nanofibers into the polymer. It is also found that surface treatment of carbon nanofibers can lead to better fiber distribution in the matrix.