Highly conducting poly(methyl methacrylate)/carbon nanotubes composites: Investigation on their thermal, dynamic-mechanical, electrical and dielectric properties

International audienceNanocomposites of poly(methyl methacrylate) (PMMA) containing various multi-walled carbon nanotubes (MWCNT) contents were prepared using melt mixing. Several techniques were employed to study the influence of the MWCNT addition on the thermal, mechanical, electrical and dielectric properties of the PMMA matrix. The electrical percolation threshold () was found to be 0.5 vol.% by performing AC and DC conductivity measurements. Significantly high conductivity levels () were achieved: exceeds 10 S/cm already at 1.1 vol.%, the criterion for EMI shielding ( > 10 S/cm) is fulfilled at 2.9 vol.%, and the highest loaded sample (5.2 vol.%) gave a maximum value of 0.5 S/cm. Dielectric relaxation spectroscopy measurements in broad frequency (10−10 Hz) and temperature ranges (-150 to 170 °C) indicated weak polymer-filler interactions, in consistency with differential scanning calorimetry and dynamic mechanical analysis findings. Weak polymer-filler interactions and absence of crystallinity facilitate the achievement of high conductivity levels in the nanocomposites

Influence of surface treatment of multiwall carbon nanotubes on the properties of polypropylene/carbon nanotubes nanocomposites

Nanocomposites based on polypropylene (PP) and surface modified multiwall carbon nanotubes (CNT) were prepared by melt mixing. For comparison, unmodified CNT were also used as fillers. The surface modification of CNT was done by treatment with a combination of anionic and cationic surfactants at different molar ratios using week and strong sonication power output during modification. The modification of nanotubes was done to improve the filler dispersibility in the PP matrix. However, the modification of the filler resulted only in small morphological differences of prepared composites, but the electrical conductivity of the samples depends on filler type and content. Mechanical and thermal properties of the nanocomposites were studied and the results are discussed in relation with the preparation parameters during the modification of CNT. © 2010 John Wiley & Sons, Ltd

A comparative study on the Electrical and mechanical behaviour of multi-walled carbon nanotube composites prepared by diluting a masterbatch with various types of polypropylenes

Polypropylene (PP) nanocomposites with multi-walled carbon nanotubes (CNT) were produced by a small-scale masterbatch melt dilution technique using five PP differing in melt flow index (MFI) and degree of maleination. PP used in a masterbatch has MFI = 12 (PP12), the others used PP which have MFI = 2 or MFI = 8. The state of CNT dispersion as assessed by melt rheological and morphological investigations indicated a better dispersion when using unmodified PP with MFI = 8 (PP8) and the masterbatch's PP12. Electrical conductivity results showed nanotube percolation at contents between 1.1 and 2.0 vol %, whereas lower values were obtained for the matrices with the best dispersion, i.e., PP8 and PP12. The dependencies of the relative Young's modulus on the CNT content showed that the maleinization improved the interfacial interactions between the components, especially in the case of maleated PP with MFI = 8 (PP-MA8), but the better dispersion was prevented by the incompatibility between polar groups of PP-MA and the nonpolar origin masterbatch PP12. © 2009 Wiley Periodicals, Inc

Thermal and electrical characterization of multi-walled carbon nanotubes reinforced polyamide 6 nanocomposites

In this study composites of polyamide 6 and multiwalled carbon nanotubes (MWCNT) were prepared by diluting a masterbatch using melt mixing. Differential scanning calorimetry was employed in order to investigate the influence of nanotubes on the thermal transitions of polyamide 6. Significant changes are reported on crystallization and glass transition by the addition of nanotubes. The results are discussed in terms of polymer-filler interactions. Dielectric relaxation spectroscopy measurements were performed to study both the electrical and dielectric properties of the nanocomposites. Percolation threshold is calculated to be at 1.7 vol.% MWCNT