Processing and property investigation of single-walled carbon nanotube (SWNT) buckypaper/epoxy resin matrix nanocomposites

Due to their extraordinary high modulus and strength, single-walled carbon nanotubes (SWNTs) are considered by many researchers as the most promising reinforcement materials for use in high performance composites. However, fabricating SWNT-reinforced composites with good tube dispersion and high SWNT loading is a great challenge since SWNTs have a strong tendency to form bundles or ropes and rapidly increase the viscosity during processing. In this research, a new method was developed to fabricate nanocomposites with preformed SWNT networks and high tube loading. SWNTs were first dispersed in water-based suspension with the aid of surfactant and sonication. Through a filtration process, SWNTs were fabricated into thin membranes called buckypapers to form networks of SWNT ropes. The tube/resin impregnation of the produced buckypaper was realized by infiltrating acetone diluted epoxy resin (Epon 862/EPI Cure W system) along the thickness direction. A hot press molding process was used for curing to produce the final nanocomposites of multiple layer buckypapers with high SWNT loading (up to 39 wt%). Dynamic mechanical analysis (DMA) results show that the storage moduli of the resulting nanocomposites were as high as 15 Gpa. The DMA results also indicate that the nanotubes had a strong influence on the composites damping properties. The through thickness permeability of the resulting buckypapers with nanoscale pore structure was also measured. AFM and SEM observations show that the SWNTs have a good dispersion in the buckypaper and nanocomposites. The research results show that the proposed buckypaper/resin infiltration approach is capable of fabricating nanocomposites with controllable nanostructure and high SWNT loading, which are important for developing high performance nanotube-based composites. q 2004 Elsevier Ltd. All rights reserved.