Complementary effects of multiwalled carbon nanotubes and conductive carbon black on polyamide 6

This article introduces a newly innovative idea for preparation of superconductive ternary polymeric composites of polyamide 6 (PA6), conductive carbon black (CCB), and multiwalled carbon nanotubes (MWCNTs) with different weight ratios by a melt‐mixing technique. The complementary effects of CCB and MWCNTs at different compositions on rheological, physical, morphological, thermal, and dynamic mechanical and electrical properties of the ternary composites have been examined systematically. We have used a novel formulation to produce high‐weight fraction ternary polymer composites that show extremely higher conductivity when compared with their corresponding binary polymer composites at the same carbon loading. For example, with an addition of 10 wt % MWCNTs into the CCB/PA6 composite preloaded with 10 wt % CCB, the electrical conductivity of these ternary composites was about 5 S/m, which was 10 times that of the CCB/PA6 binary composite (0.5 S/m) and 125 times that of the MWCNT/PA6 binary composite (0.04 S/m) at 20 wt % carbon loading. The incorporation of the MWCNTs effectively enhanced the thermal stability and crystallization of the PA6 matrix in the CCB/PA6 composites through heterogeneous nucleation. The MWCNTs appeared to significantly affect the mechanical and rheological properties of the PA6 in the CCB/PA6 composites, a way notably dependent on the MWCNT contents. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1203–1212, 2010     

Structural and morphological studies on the deformation behavior of polypropylene/multi‐walled carbon nanotubes nanocomposites prepared through ultrasound‐assisted melt extrusion process

Structural and morphological behavior under stress–strain of polypropylene/multi‐walled carbon nanotubes (PP/MWCNTs) nanocomposites prepared through ultrasound‐assisted melt extrusion process was studied by means of optical microscopy, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, small angle X‐ray scattering (SAXS), and wide angle X‐ray scattering (WAXS). A high ductile behavior was observed in the PP/MWCNT nanocomposites with low concentration of MWCNTs. This was related to an energy‐dissipating mechanism, achieved by the formation of an ordered PP‐CNTs interphase zone and crystal oriented structure in the undeformed samples. Different strain‐induced‐phase transformations were observed by ex situ SAXS/WAXS, characterizing the different stages of structure development during the deformation of PP and PP/MWCNTs nanocomposites. The high concentration of CNTs reduced the strain behavior of PP due to the agglomeration of nanoparticles. A structural pathway relating the deformation‐induced phase transitions and the dissipation energy mechanism in the PP/MWCNTs nanocomposites at low concentration of nanoparticles was proposed. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 475–491     

Rheological and electrical properties of polypropylene/MWCNT composites prepared with MWCNT masterbatch chips

Melt compounded PP/MWCNT (polypropylene/multi-walled carbon nanotube) composites were prepared by diluting highly concentrated masterbatch chips. Maleic anhydride grafted polypropylene (PP-g-MAH) was used as a compatibilizer to promote dispersion and interaction of MWCNTs. Rheological properties were investigated with respect to the MWCNT and compatibilizer loadings, and related to morphological and electrical properties. As the MWCNT loading was increased, shear viscosity and yield stress were increased at low shear rate region because of increased interaction between MWCNT particles. When the MWCNT loading was low, MWCNT dispersion was improved by the PP-g-MAH compatibilizer because MWCNTs were wetted sufficiently due to the presence of the compatibilizer. However, rheological and electrical properties of highly concentrated MWCNT composites with the compatibilizer were not improved compared with PP/MWCNT composites without the compatibilizer because the compatibilizer did not provide sufficient wrapping of MWCNT particles. Electrical and morphological properties of PP/MWCNT composites were correlated with the rheological properties in steady and dynamic oscillatory shear flows.     

Ethylene–acrylic acid copolymer induced electrical conductivity improvements and dynamic rheological behavior changes of polypropylene/carbon black composites

The experimental data reveal that the addition of ethylene–acrylic acid copolymer (EAA) into carbon black (CB)/polypropylene (PP) composites can improve the electrical conductivity of CB/PP composites by two to six orders of magnitude at a comparatively low CB content (φ), and when φ = 2.5 vol %, 60/40 of PP/EAA is an optimum for electrical conductivity improvement. The dynamic rheological data show that with increasing φ there are apparent rheological percolations for CB/PP composites. A modified Kerner–Nielson equation can be used to describe the correlation between electrical percolation and dynamic viscoelastic percolation. The addition of EAA into CB/PP composites leads to apparent changes in dynamic rheological behaviors. When φ = 2.5 vol %, a rheological percolation appears in CB/PP/EAA (CPE) composites with increasing EAA content. The similar rheological behaviors correspond to the similar morphological structures for CPE composites with φ = 5.0 vol %. The appearance of bumps in the van‐Gurp–Palmen plots corresponds to the formation of network structure in CB/PP and CPE composites, and the more perfect the networks, the higher the amplitude of the bumps. All data indicate that the van‐Gurp–Palmen plot is sensitive to the formation of filler particle networks or cocontinuous phase which spans the whole composite. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1762–1771, 2009     

Dissolution of MWCNTs by using polyoxadiazoles,and highly effective reinforcement of their composite films

Nonmodified multiwalled carbon nanotubes (MWCNTs)/sulfonated polyoxadiazole (sPOD) nanocomposites are successfully prepared by a facile solution route. The pristine MWCNTs are dispersed in a sPOD solution, and the mixtures are fabricated into thin films by solution casting. The homogeneous dispersion of nanotubes in the composites is confirmed by transmission electron microscopy. The mechanical properties, thermal stability, and electrical conductivity are investigated. Tensile strength, elongation at break, and tensile energy to break are shown to increase by more than 28, 45, and 73%, respectively, by incorporating up to 1.0 wt % pristine MWCNTs. The experimental values for sPOD/MWCNTs composite stiffness are compared with Halpin‐Tsai and modified Halpin‐Tsai predictions. The storage modulus is found to increase up to 10% at low CNT loading. The composite films, which have an outstanding thermal stability, show an increase of up to 57 °C in the initial degradation temperature. The addition of 1.0 wt % MWCNTs increases the electrical conductivity of the sPOD matrix by two orders of magnitude. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Preparation of conductive PTFE nanocomposite containing multiwalled carbon nanotube via latex heterocoagulation approach

Conductive poly(tetrafluoroethylene) (PTFE) composites containing surface-modified multiwalled carbon nanotubes (MWCNTs) were prepared by a simple heterocoagulation process in water. Two different types of MWCNT were used and compared: carboxylated MWCNT and cetyltrimethyl ammonium bromide (CTAB)-stabilized MWCNT. Aqueous PTFE dispersion was mixed with the well-dispersed MWCNT dispersions and they were heterocoagulated with the aid of a flocculant, polyaluminum chloride at an elevated temperature. After particle growth and successive stabilization step, particulated PTFE/MWCNT composites were prepared in the size range of 10–100 μm. The MWCNT-containing PTFE composites have improved thermal stability and electrical conductivity. Importantly, the percolation threshold for the electrical conductivity was achieved at a low concentration of MWCNT using this heterocoagulation process.     

Semiconductive bionanocomposites of poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) and MWCNTs for neural growth applications

Bionanocomposites of poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (P3HB3HHx) (13 % by mol of HHx) with multiwalled carbon nanotubes (MWCNTs) were prepared to obtain semiconductive nanocomposites for potential applications as scaffolds for nerve repair. The effect of the polymer/nanotube interface on the composite properties was studied using oxidized (oxi‐MWCNTs) and surface modified MWCNTs with low‐molecular weight P3HB3HHx (pol‐MWCNTs), in a ratio from 0.3 to 1.2 wt % for each type of MWCNTs employed. Morphology and conductive properties of the composites indicated a good interaction between pol‐MWCNTs and the polymer matrix. Composites with improved conductivity were obtained with only 0.3 wt % of pol‐MWCNTs added. However, agglomeration and lower conductivity was observed for samples with oxi‐MWCNTs. Cell viability studies carried out with neurospheres showed that samples with 1.2 wt % of pol‐MWCNTs are not cytotoxic and, in addition favors the neurospheres growth on the composite surface. Considering the electrical properties and biological behavior, nanocomposites of P3HB3HHx and pol‐MWCNTs are promising substrates for the regeneration of nerve tissue. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 349–360     

Synthesis and Characterization of Multi‐Walled Carbon Nanotube/Polythiophene Composites

Multi‐walled carbon nanotube (MWCNT)/polythiophene (PTh) composites have been prepared by in situ chemical oxidative polymerization. PTh is synthesized onto the sidewalls of the MWCNTs, which play a role as hard templates for PTh to produce one‐dimensional nanostructures. The morphology and structures of the MWCNT/PTh composites are characterized by High‐resolution transmission electron microscopy, x‐ray diffraction, and Fourier transform infrared spectrometry. Their electrical property and thermal stability are determined using vector network analyzer and thermal gravimetric analyzer. Moreover, the mechanism of MWCNT/PTh nanowire formation is described. The studies show that the composites are nanowires with core‐shell structure, in which the outer shells and inner cores are formed by PTh and MWCNTs, respectively. The addition of MWCNTs does not change the backbone structure of PTh and affect the amorphous condition of PTh very slightly, however, it improves the electrical conductivity and thermal stability of PTh.     

Melt flow behavior of polypropylene composites filled with multi-walled carbon nanotubes during extrusion

Polypropylene (PP) composites filled with multi-walled carbon nanotubes (MWCNTs) were prepared using a twin-screw extruder. The melt flow properties of the composites were measured with a capillary rheometer in a temperature range from 180 to 230 °C and at various apparent shear rates varying from 100 to 4000 s⁻¹. The results showed that the melt shear stress increased almost linearly while the melt shear viscosity decreased almost linearly with increasing shear rates in a bi-logarithmic coordinate system. The melt shear flow followed the power law relationship and the dependence of the melt shear viscosity on temperature obeyed the Arrhenius equation. The relationship between the melt shear viscosity and the MWCNT weight fraction was roughly linear under the investigated range of temperature or shear rate.     

Morphology,microhardness, and electrical properties of composites based on polypropylene,montmorillonite, and polypyrrole

The morphology, microhardness, and electrical properties of composites consisting of conductive polypyrrole (PPy) dispersed into a nonconductive polypropylene matrix (PP) as pure component or in form of a sodium montmorillonite/PPy (MMT/PPy) composite have been studied. For comparison, also PP/MMT composites were studied. All types of composites were processed by compression molding or by melt mixing followed by compression molding into plates, which were used for characterization. Scanning electron microscopy and transmission electron microscopy was used to examine the morphology of the prepared materials. The investigation of electrical and dielectric properties was done by dielectric relaxation spectroscopy in a wide frequency range and was related to the composite composition and processing method. The analysis of the conductivity as a function of temperature indicated that the charge transfer mechanism could be described by the variable range hopping model in three dimensions. The microhardness of PP/MMT/PPy composites with different content of MMT or PPy was determined and the creep rate has been estimated. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 407–423, 2009     

Melt‐crystallization mechanism of poly(ethylene terephthalate)/multi‐walled carbon nanotubes prepared by in situ polymerization

A series of poly(ethylene terephthalate)/multi‐walled carbon nanotubes (PET/MWCNTs) nanocomposites were prepared by in situ polymerization using different amounts of multi‐walled carbon nanotubes (MWCNTs). The polymerization of poly(ethylene terephthalate) (PET) was carried out by the two‐stage melt polycondensation method. The intrinsic viscosity (IV) of the composites is ranged between 0.31 and 0.63 dL/g depending on the concentration of the MWCNTs. A decrease of IV was found by increasing MWCNTs content. This is due to the reactions taking place between the two components leading to branched and crosslinked macromolecules. These reactions are, mainly, responsible for thermal behavior of nanocomposites. The melting point of the nanocomposites was shifted to slightly higher temperatures by the addition till 0.55 wt % of MWCNTs while for higher concentration was reduced. The degree of crystallinity in all nanocomposites was, also, reduced by increasing MWCNTs amount. However, from crystallization temperature, it was found that MWCNTs till 1 wt % can enhance the crystallization rate of PET, whereas at higher content (2 wt %), the trend is the opposite due to the formation of crosslinked macromolecules. From the extended crystallization analysis, it was proved that MWCNTs act as nucleating agents for PET crystallization. Additionally, the crystallization mechanism due to the existence of MWCNT becomes more complicated because two mechanisms with different activation energies are taking place in the different degrees of crystallization, depending on the percentage of MWCNT. The effect of molecular weight also plays an important role. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1452–1466, 2009     

Structural and mechanical behavior of polypropylene/ maleated styrene‐(ethylene‐co‐butylene)‐styrene/sisal fiber composites prepared by injection molding

Hybrid composites consisting of isotactic poly(propylene) (PP), sisal fiber (SF), and maleic anhydride grafted styrene‐(ethylene‐co‐butylene)‐styrene copolymer (MA‐SEBS) were prepared by melt compounding, followed by injection molding. The melt‐compounding torque behavior, thermal properties, morphology, crystal structure, and mechanical behavior of the PP/MA‐SEBS/SF composites were systematically investigated. The torque test, thermogravimetric analysis, differential scanning calorimetric, and scanning electron microscopic results all indicated that MA‐SEBS was an effective compatibilizer for the PP/SF composites, and there was a synergism between MA‐SEBS and PP/SF in the thermal stability of the PP/MA‐SEBS/SF composites. Wide‐angle X‐ray diffraction analysis indicated that the α form and β form of the PP crystals coexisted in the PP/MA‐SEBS/SF composites. With the incorporation of MA‐SEBS, the relative amount of β‐form PP crystals decreased significantly. Mechanical tests showed that the tensile strength and impact toughness of the PP/SF composites were generally improved by the incorporation of MA‐SEBS. The instrumented drop‐weight dart‐impact test was also used to examine the impact‐fracture behavior of these composites. The results revealed that the maximum impact force (F_max), impact‐fracture energy (E_T), total impact duration (t_r), crack‐initiation time (t_init), and crack‐propagation time (t_prop) of the composites all tended to increase with an increasing MA‐SEBS content. From these results, the incorporation of MA‐SEBS into PP/SF composites can retard both the crack initiation and propagation phases of the impact‐fracture process. These prolonged the crack initiation and propagation time and increased the energy consumption during impact fracture, thereby leading to toughening of PP/MA‐SEBS/SF composites. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1214–1222, 2002     

Significant enhancement of electrical and thermal conductivities of polyethylene carbon nanotube composites by the addition of a low amount of silver nanoparticles

Electrically and thermally conductive high‐density polyethylene composites filled with hybrid fillers, multiwall carbon nanotubes (MWCNTs) and silver nanoparticles (Ag‐NPs), have been prepared in the melt state. The investigation of their electrical and thermal conductivities while comparing with high‐density polyethylene/MWCNT binary composites shows that the addition of only 3 vol% of Ag‐NPs does not reduce the electrical percolation threshold (P_c) that remains as low as 0.40 vol% of MWCNTs but leads to an increase in the maximum dc electrical conductivity of PE/MWCNT composites by two orders of magnitudes. Moreover, the association of both Ag‐NPs and carbon nanotube particles improved our composite's thermal conductivity. Copyright © 2014 John Wiley & Sons, Ltd.     

Noncovalent functionalization of multiwalled carbon nanotubes using graft copolymer with naphthalene and its application as a reinforcing filler for poly(styrene‐co‐acrylonitrile)

A new compatibilizer, poly(vinyl benzyloxy ethyl naphthalene)‐graft‐poly(methyl methacrylate), for poly(styrene‐co‐acrylonirile) (SAN)/multi‐walled carbon nanotubes (MWCNTs) composites was synthesized. It has been identified that naphthalene unit in backbone of compatibilizer interacts with MWCNTs via π? π interaction and that the PMMA graft of the compatibilizer is miscible with the SAN matrix. When a small amount of compatibilizer was added to SAN/MWCNT composites, MWCNTs were more homogeneously dispersed in SAN matrix than the case without compatibilizer, indicating that the compatibilizer improves the compatibility between SAN and MWCNTs. As a consequence, mechanical and electrical properties of the composites with compatibilizer were largely improved as compared with those of composites without compatibilizer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4184–4191, 2010     

Isothermal crystallization kinetics of polypropylene/POSS composites

Polypropylene (PP)/octavinyl polyhedral oligomeric silsesquioxane (POSS) composites were prepared by two different processing methods: reactive blending and physical blending, and the crystallization behavior of PP and PP/POSS composites was studied by means of differential scanning calorimetry and polarized optical microscope. The results showed that the crystallization of PP in PP/POSS composites was strongly influenced by the different processing methods. POSS particles can act as effective nucleating agent, accelerating the crystallization of PP. The crystallization rate increased more dramatically for the reactive blending composite due to the stronger nucleating effect of PP grafted POSS. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1762–1772, 2008     

Multifunctional poly(2,5‐benzimidazole)/carbon nanotube composite films

The AB‐monomer, 3,4‐diaminobenzoic acid dihydrochloride, was recrystallized from an aqueous hydrochloric acid solution and used to synthesize high‐molecular‐weight poly(2,5‐benzimidazole) (ABPBI). ABPBI/carbon nanotube (CNT) composites were prepared via in situ polymerization of the AB‐monomer in the presence of single‐walled carbon nanotube (SWCNT) or multiwalled carbon nanotube (MWCNT) in a mildly acidic polyphosphoric acid. The ABPBI/SWCNT and ABPBI/MWCNT composites displayed good solubility in methanesulfonic acid and thus, uniform films could be cast. The morphology of these composite films was studied by X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. The results showed that both types of CNTs were uniformly dispersed into the ABPBI matrix. Tensile properties of the composite films were significantly improved when compared with ABPBI, and their toughness (～200 MPa) was close to the nature's toughest spider silk (～215 MPa). The electrical conductivities of ABPBI/SWCNT and ABPBI/MWCNT composite films were 9.10 × 10^?5 and 2.53 × 10^?1 S/cm, respectively, whereas that of ABPBI film was 4.81 × 10^?6 S/cm. These values are ～19 and 52,700 times enhanced by the presence of SWCNT and MWCNT, respectively. Finally, without acid impregnation, the ABPBI film was nonconducting while the SWCNT‐ and MWCNT‐based composites were proton conducting with maximum conductivities of 0.018 and 0.017 S/cm, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1067–1078, 2010     

Isothermal crystallization kinetics of polypropylene with silane functionalized multi‐walled carbon nanotubes

Multi‐walled carbon nanotubes (MWNTs) were functionalized with a silane coupling agent. The MWNTs were first coated with inorganic silica by a sol‐gel process and then grafted with 3‐methacryloxypropyltrimethoxysilane (3‐MPTS). The effect of raw MWNTs and silane‐functionalized MWNTs on the crystallization behavior of poly(propylene) (PP) was investigated by means of polarized optical microscopy, differential scanning calorimetry, and wide‐angle X‐ray diffraction. Results obtained from isothermal crystallization experiments indicate that 3‐MPTS functionalization affects the crystallization and melting behavior of PP/MWNTs composites remarkably, which can be attributed to the fact that 3‐MPTS functionalization of MWNTs leads to a uniform dispersion of MWNTs in PP matrix resulting in the good nucleating effect of MWNTs. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1616–1624, 2007     

Synthesis of metal (Fe or Pd)/alloy (Fe–Pd)‐nanoparticles‐embedded multiwall carbon nanotube/sulfonated polyaniline composites by γ irradiation

Composites of multiwall carbon nanotubes (MWCNTs) and sulfonated polyaniline (SPAN) were prepared through the oxidative polymerization of a mixture of aniline, 2,5‐diaminobenzene sulfonic acid, and MWCNTs. Fe, Pd, or Fe–Pd alloy nanoparticles were embedded into the MWCNT–SPAN matrix by the reduction of Fe, Pd, or a mixture of Fe and Pd ions with γ radiation. Sulfonic acid groups and the emeraldine form of backbone units in SPAN served as the source for the reduction of the metal ions in the presence of γ radiation. The existence of metallic/alloy particles in the MWCNT–SPAN matrix was further ascertained through characterization by high‐resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, thermogravimetric analysis, and conductivity measurements. HRTEM pictures clearly revealed the existence of Fe, Pd, and Fe–Pd nanoparticles of various sizes in the MWCNT–SPAN matrices. There were changes in the electronic properties of the MWCNT–SPAN–M composites due to the interaction between the metal nanoparticles and MWCNT–SPAN. Metal‐nanoparticle‐loaded MWCNT–SPAN composites (MWCNT–SPAN–M; M = Fe, Pd, or Fe–Pd alloy) showed better thermal stability than the pristine polymers. The conductivity of the MWCNT–SPAN–M composites was approximately 1.5 S cm^?1, which was much higher than that of SPAN (2.46 × 10^?4 S cm^?1). Metal/alloy‐nanoparticle‐embedded, MWCNT‐based composite materials are expected to find applications in molecular electronics and other fields. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3355–3364, 2006     

Studies on fracture behaviors of immiscible polypropylene/ethylene‐co‐vinyl acetate blends with multiwalled carbon nanotubes

Immiscible polypropylene/ethylene‐co‐vinyl acetate (PP/EVA) blends with two different compositions, one (PP/EVA = 80/20) exhibits the typical sea‐island morphology and the other (PP/EVA = 60/40) exhibits the cocontinuous morphology, were prepared with different contents of f‐MWCNTs. The fracture behaviors, including notched Izod impact fracture and single‐edge notched tensile (SENT) fracture, were comparatively studied to establish the role of f‐MWCNTs in influencing the fracture toughness of PP/EVA blends. Our results showed that, for PP/EVA (80/20) system, f‐MWCNTs do not induce the fracture behavior change apparently. However, for PP/EVA (60/40) system, the fracture toughness of the blend increases dramatically with the increasing of f‐MWCNTs content. More severe plastic deformation accompanied by the fibrillar structure formation was observed during the SENT test. Furthermore, SENT test shows that the significant improvement in fracture toughness of PP/EVA (60/40) with f‐MWCNTs is contributed to the simultaneous enhancement of crack initiation energy and crack propagation energy, but largely dominated by crack propagation stage. Further results based on crystalline structures and morphologies of the blends showed that a so‐called dual‐network structure of EVA and f‐MWCNTs forms in cocontinuous PP/EVA blends, which is thought to be the main reason for the largely improved fracture toughness of the sample. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1331–1344, 2009     

Uncross‐linked polypropylene (PP)/ethylene‐propylene‐diene (EPDM)/multi walled carbon nanotube (MWCNT) and dynamically vulcanized PP/EPDM/MWCNT nanocomposites

In this study, relatively large amounts of polypropylene (PP), ethylene‐propylene‐diene (EPDM), and multi‐walled carbon nanotube (MWCNT) were melt‐mixed with and without DCP. Dynamically vulcanized PP/EPDM (TPV)/MWCNT nanocomposites were prepared by two methods: the MWCNTs were added either before or after the dynamic vulcanization of the blends. The effects of composition, rotor speed, and dynamic vulcanization on their surface resistivity were investigated. The surface resistivity of uncross‐linked PP/EPDM/MWCNT nanocomposites increases with increasing the content of EPDM. At PP/EPDM (70/30 wt%) nanocomposite with 1.5 phr MWCNT, slightly lower surface resistivity is obtained by increasing the rotor speed during mixing. However, for PP/EPDM (50/50 wt%) and PP/EPDM (30/70 wt%) nanocomposites, surface resistivity decreases with increasing the rotor speed from 30 to 60 rpm. But further increase in rotor speed (90 rpm) leads to an increase of surface resistivity. When the MWCNTs were added after the dynamic vulcanization of the blends, the surface resistivity of TPV70/MWCNTnanocomposite is lower than that of uncross‐linked PP/EPDM/MWCNT nanocomposite. However, when the MWCNTs were added before the dynamic vulcanization of the blends, the surface resistivity of TPV70/MWCNT nanocomposite is >10¹² Ω/square. Copyright © 2010 John Wiley & Sons, Ltd.