High performance PEEK/carbon nanotube composites compatibilized with polysulfones-II. Mechanical and electrical properties

The mechanical and electrical properties of poly(ether ether ketone) (PEEK)/single-walled carbon nanotube (SWCNT) composites with polysulfones as compatibilizers have been analyzed. Dynamic mechanical studies reveal that these composites exhibit considerably higher storage modulus and glass transition temperature than non-compatibilized samples. Tensile tests indicate a non-linear growth in the Young's modulus and strength with increasing SWCNT loading, related to changes in the degree of crystallinity of the composites. The moduli of samples with very low CNT content exceed the predictions by the rule of mixtures, whilst at higher concentrations fall slightly below the theoretical values. The addition of the polysulfones increases the stiffness and toughness of the composites, attributed to an improved filler dispersion and stronger matrix-reinforcement interfacial adhesion. Fractography analyses suggest that these compatibilizers favor the ductile deformation of the matrix. The electrical and thermal conductivities of the composites decrease slightly in the presence of the polysulfones, albeit are well above the values of pure PEEK. Enhanced properties are found for samples including wrapped laser-grown SWCNTs. The overall mechanical performance of the compatibilized composites is suitable for use in lightweight structural applications, particularly for the aeronautic industry. (C) 2010 Elsevier Ltd. All rights reserved.