The influence of a compatibilizer on the thermal and dynamic mechanical properties ofPEEK/carbon nanotube composites

Abstract

The effect of polyetherimide (PEI) as a compatibilizing agent on the morphology,thermal, electrical and dynamic mechanical properties of poly(ether ether ketone)(PEEK)/single-walled carbon nanotube (SWCNT) nanocomposites, has been investigatedfor different CNT loadings. After a pre-processing step based on ball milling andpre-mixing under mechanical treatment in ethanol, the samples were prepared by meltextrusion. A more homogeneous distribution of the CNTs throughout the matrix isfound for composites containing PEI, as revealed by scanning electron microscopy.Thermogravimetric analysis demonstrates an increase in the matrix degradationtemperatures under dry air and nitrogen atmospheres with the addition of SWCNTs; thelevel of thermal stability of these nanocomposites is maintained when PEI is incorporated.Both differential scanning calorimetry and synchrotron x-ray scattering studies indicate aslight decrease in the crystallization temperatures of the compatibilized samples, andsuggest the existence of reorganization phenomena during the heating, which are favouredin the composites incorporating the compatibilizer, due to their smaller crystal size.Dynamic mechanical studies show an increase in the glass transition temperature of thenanocomposites upon the addition of PEI. Furthermore, the presence of PEIcauses an enhancement in the storage modulus, and hence in the rigidity of thesesystems, attributed to an improved interfacial adhesion between the reinforcementand the matrix. The electrical and thermal conductivities of these compositesdecrease with the incorporation of PEI. Overall, the compatibilized samples exhibitimproved properties and are promising for their use in industrial applications.