Dispersion of Carbon Nanotubes into Thermoplastic Polymers using Melt Mixing

Abstract. This paper presents melt mixed composites where two ways of introducing nanotubes in polymer matrices were used. In the first case, commercially available masterbatches of nanotube /polymer composites are used as the starting material which are diluted by the pure polymer in a subsequent melt mixing process (masterbatch dilution method) while in the other case nanotubes are directly incorporated into the polymer matrix. As an example of the masterbatch dilution method, composites of polycarbonate with MWNT are presented which are produced using different melt mixing equipments. The lowest percolation threshold was found at about 0.5 wt % MWNT using a Brabender PL-19 single screw extruder. The nanotube dispersion as observed by TEM investigations is quite homogeneous. The direct incorporation method is discussed in composites of polycarbonate with MWNT and SWNT. The nanotube addition significantly changes the stress-strain behavior of the composites: modulus and stress are increased; however, elongation is reduced especially above the percolation concentration