Low Carbon Nanotube Loading Research Articles

Structure-properties relationships in new polymer nanocomposites based on the renewable poly(butylene succinate) filled with low amounts of nanoparticles of 1-3D geometries

A series of polymer nanocomposites (PNCs) based on the renewable poly(butylene-succinate) (PBSu) reinforced with 1 wt% of different nanoparticles (NP), namely, silica (SiO2), montmorillonite (MMT), graphene oxide (GO) and carbon nanotubes (CNT), were synthesized and studied herein. The investigation focuses on both the direct and indirect NP effects on the interfacial interactions, thermal transitions, crystallinity, electrical and thermal conductivity, mechanical properties and molecular dynamics. For that, a sum of complementary techniques was employed, regarding both the structure and performance. The clearly direct effect is related to the promotion of crystal nucleation at the presence of both particles, related to the fillers’ dimensionality (aspect ratio) and the non-worth noting interfacial interactions. The degree of crystallinity of PBSu mildly increases, whereas the semicrystalline morphology (sizes, numbers, distributions of the crystals) is systematically denser in the PNCs. In agreement with previous findings on PBSu, the polymer cannot be preserved amorphous, at least by conventional methods. Consequently, the macroscopic properties, namely, the thermal diffusivity/conductivity as well as the mechanical performance were found connected to crystallinity, in particular, to the semicrystalline morphology (indirect filler effect). PBSu/CNT was surprisingly found electrically conductive, despite the low CNT loading, whereas the rest of the samples are insulating. The molecular dynamics map was constructed here for the first time, obviously only for the semicrystalline state. The cooperativity of PBSu chains drops in the PNCs, most probably, affected by the dense semicrystalline structures that seem to impose an increase in the free volume of the amorphous polymer fraction. Overall, the PBSu PNCs were found to offer potentials for wide range manipulation of properties, via relatively mild processing (synthesis, thermal treatments).

High‐strength and antistatic PET/CNTs bead foams prepared by scCO2 foaming and microwave sintering

AbstractThis paper reported the high strength and antistatic polyethylene terephthalate (PET) bead foam with a typical segregated structure prepared by supercritical carbon dioxide (scCO2) foaming and microwave selective sintering. Firstly, carbon nanotubes (CNTs) were coated on the surface of PET pellets, and then the composite foam with segregated structure was prepared via scCO2 foaming in a confined mold. The interfaces among PET foamed beads were further sintered by utilizing the selective heating behaviors of microwave, which greatly enhanced the interfacial strength and thus the overall mechanical strength of bead foam. The final composite foam showed an electrical conductivity of 0.004 S/m with an extremely low CNTs loading of 0.138 vol%, and its mechanical strength reached as high as 10.44 MPa, far superior to the composite without microwave treatment. Thus, the problem in the welding of PET bead foams and antistatic properties could be solved. The effect of the foaming conditions on the structure and properties of PET foam were systematically investigated, providing a novel method for the preparation of high strength and antistatic engineering plastics composite foam.

A novel interpenetrating segregated functional filler network structure for ultra-high electrical conductivity and efficient EMI shielding in CPCs containing carbon nanotubes

Inspired by the hierarchically dendritic structure of plant root and its extraordinary ability of grabbing soil, polyurethane (PU) fibers with such bio-mimic structure were fabricated by non-solvent induced precipitation under turbulent force to grab multi-walled carbon nanotubes (CNTs) in this work, forming interpenetrating segregated network (IPSN) with CNTs coated on hierarchically dendritic polyurethane (PU) fibers (HDPUFs) and filled into voids between entangled HDPUFs. Prepared CNT/PU composites illustrate an ultrahigh maximum CNT loading of 80 wt% with good flexibility, while only 10% could be achieved for common segregated structure. Meanwhile, a low percolation threshold of 0.25 wt% and a maximum conductivity of 25 S/cm is achieved. Benefiting from significantly reduced insulating polymer coating on CNTs, the electrical conductivity of CNT/HDPUF composites at low CNT loading (≤7 wt%) is orders of magnitude higher than that of CNT/PU composites containing randomly dispersed CNTs with similar filler content. Simultaneously, the specific electromagnetic interference (EMI) shielding efficiency (SE) of CNT/HDPUF composite reaches up to 10526.1 dB cm2/g thanks to their high electrical conductivity and low density, which has been rarely reported previously for CNT-based composites. This work provides a simple and low-cost method to fabricate thin, lightweight, and flexible composite with high filler content, high electrical conductivity and outstanding electromagnetic shielding performance.

Effect of the selective localization of carbon nanotubes and phase domain in immiscible blends on tunable microwave dielectric properties

In recent years, the immiscible polymer blend system has attracted much attention as the matrix of nanocomposites. Herein, from the perspective of dynamics, the control of the carbon nanotubes (CNTs) migration aided with the interface of polystyrene (PS) and poly (methyl methacrylate) (PMMA) blends was achieved through a facile melt mixing method. Thus, we revealed a comprehensive relationship between several typical CNTs migrating scenarios and the microwave dielectric properties of their nanocomposites. Based on the unique morphologies and phase domain structures of the immiscible matrix, we further investigated the multiple microwave dielectric relaxation processes and shed new light on the relation between relaxation peak position and the phase domain size distribution. Moreover, by integrating the CNTs interface localization control with the matrix co-continuous structure construction, we found that the interface promotes double percolation effect to achieve conductive percolation at low CNTs loading (~1.06 vol%). Overall, the present study provides a unique nanocomposite material design symphonizing both functional fillers dispersion and location as well as the matrix architecture optimization for microwave applications.

Carbon Nanotube/Poly(dimethylsiloxane) Composite Materials to Reduce Bacterial Adhesion.

Different studies have shown that the incorporation of carbon nanotubes (CNTs) into poly(dimethylsiloxane) (PDMS) enables the production of composite materials with enhanced properties, which can find important applications in the biomedical field. In the present work, CNT/PDMS composite materials have been prepared to evaluate the effects of pristine and chemically functionalized CNT incorporation into PDMS on the composite’s thermal, electrical, and surface properties on bacterial adhesion in dynamic conditions. Initial bacterial adhesion was studied using a parallel-plate flow chamber assay performed in conditions prevailing in urinary tract devices (catheters and stents) using Escherichia coli as a model organism and PDMS as a control due to its relevance in these applications. The results indicated that the introduction of the CNTs in the PDMS matrix yielded, in general, less bacterial adhesion than the PDMS alone and that the reduction could be dependent on the surface chemistry of CNTs, with less adhesion obtained on the composites with pristine rather than functionalized CNTs. It was also shown CNT pre-treatment and incorporation by different methods affected the electrical properties of the composites when compared to PDMS. Composites enabling a 60% reduction in cell adhesion were obtained by CNT treatment by ball-milling, whereas an increase in electrical conductivity of seven orders of magnitude was obtained after solvent-mediated incorporation. The results suggest even at low CNT loading values (1%), these treatments may be beneficial for the production of CNT composites with application in biomedical devices for the urinary tract and for other applications where electrical conductance is required.

Excellent electromagnetic interference shielding characteristics of a unidirectionally oriented thin multiwalled carbon nanotube/polyethylene film

In this study, we synthesized oriented multiwalled carbon nanotube (CNT)/polyethylene (PE) composite films and investigated their electromagnetic interference (EMI) shielding properties. The oriented CNT sheet structure was prepared by stacking CNT webs produced by a dry spinning technique with a CNT forest. In a near-field EMI attenuation measurement by a microstrip line method, composite films with a CNT fraction higher than 2 wt% showed a high attenuation that exceeded 50 dB at 10 GHz. This high attenuation was due to the enhanced magnetic anisotropy of the oriented CNTs and the encapsulated catalyst-derived cementite nanoparticles. This is the first report of high magnetic anisotropy in an oriented CNT structure for noise attenuation in a transmission line. In a far-field EMI shielding measurement by a coaxial tube method, the EMI shielding effectiveness (SE) significantly increased as the number of CNT web layers increased. A CNT/PE film with a high CNT fraction was found to have a high specific EMI SE of 0.6 dB/μm. The oriented CNT/PE composite film has great potential as a promising EMI material that demonstrates high shielding efficiency performance with low CNT loading.

Electrically Conductive CNT Composites at Loadings below Theoretical Percolation Values.

It is well established that dramatic increases in conductivity occur upon the addition of conductive filler materials to highly resistive polymeric matrices in experimental settings. However, the mechanisms responsible for the observed behavior at low filler loadings, below theoretical percolation limits, of even high aspect ratio fillers such as carbon nanotubes (CNT) are not completely understood. In this study, conductive composites were fabricated using CNT bundles dispersed in epoxy resins at diverse loadings, using different dispersion and curing protocols. Based on electron microscopy observation of the CNTs strands distribution in the polymeric matrices and the corresponding electrical conductivities of those specimens, we concluded that no single electron transfer model can accurately explain the conductive behavior for all the loading values. We propose the existence of two different conductive mechanisms; one that exists close to the percolation limit, from ‘low loadings’ to higher CNT contents (CNT % wt > 0.1) and a second for ‘extremely low loadings’, near the percolation threshold (CNT % wt < 0.1). The high conductivity observed for composites at low CNT loading values can be explained by the existence of a percolative CNT network that coexists with micron size regions of non-conductive material. In contrast, samples with extremely low CNT loading values, which present no connectivity or close proximity between CNT bundles, show an electrical conductivity characterized by a current/voltage dependence. Data suggests that at these loadings, conduction may occur via a material breakdown mechanism, similar to dielectric breakdown in a capacitor. The lessons learned from the data gathered in here could guide future experimental research aimed to control the conductivity of CNT composites.

Low loading carbon nanotubes supported polypyrrole nano metacomposites with tailorable negative permittivity in radio frequency range

Abstract Metacomposites with conductive polymer matrix toward negative permittivity have promising applications in energy storage devices and electromagnetic shielding. In this paper, carbon nanotubes (CNTs)/polypyrrole (PPy) nanocomposites with different loadings of CNTs have been synthesized using a surface-initiated polymerization (SIP) method. Scanning electron microscopy (SEM) results indicate that conductive networks have constructed inside the nanocomposites by CNTs and PPy granules. A frequency switch of permittivity from positive to negative in pure PPy and CNTs/PPy nanocomposites with low CNTs loading (1 wt%) is observed, which can be analyzed by the Lorentz model. Besides, all negative permittivity behavior in the test frequency range (10–1000 MHz) is found in CNTs/PPy nanocomposites with higher CNTs content which can be easily tuned by adjusting the CNTs loading. Negative permittivity is considered arising from the plasma oscillation of delocalized electrons in conductive networks and could be fitted by Drude model. Furthermore, the equivalent circuit models, ac conductivity and dielectric loss are discussed.

Biodegradation of Carbon Nanotube/Polymer Nanocomposites using a Monoculture.

The biodegradation rates of carbon nanotube (CNT)/ polymer nanocomposites (PNCs) containing poly-ε-caprolactone (PCL) were investigated using Pseudomonas aeruginosa, a microorganism commonly found in the environment. CNT/PCL nanocomposite mass loss profiles revealed that the rate of PCL matrix biodegradation decreased systematically as the CNT loading increased from 0.1 to 10% w/w. Addition of even a low CNT loading (<1% w/w) caused the CNT/PCL biodegradation rate constant to decrease by more than 50%. Similar trends in biodegradation rate were observed for both pristine and oxidized multiwall CNTs embedded in PCL. During PCL matrix biodegradation, CNT accumulation was observed at the surface of CNT/PCL nanocomposites and single particle inductively coupled-mass spectrometry experiments revealed no measurable CNT release to the culture fluid. Experimental data indicated that biodegradation proceeded as a result of biofilm formation on the CNT/PCL nanocomposites and decreased as a function of CNT loading due to the cytotoxicity of CNTs toward P. aeruginosa and the physical barrier presented by the surface-accumulated CNTs to the underlying PCL substrate. As the CNT loading in the CNT/PCL nanocomposites increased, the microbial proliferation of planktonic cells in the surrounding media also decreased as did the biodegradation rate of PCL samples present in the same reactors. Results from this study demonstrate that the inclusion of CNTs into polymer matrices could increase the environmental persistence of polymers in lakes, landfills, and surface waters.

Low-Cost Carbon Fillers to Improve Mechanical Properties and Conductivity of Epoxy Composites.

In recent years, low-cost carbons derived from recycled materials have been gaining attention for their potentials as filler in composites and in other applications. The electrical and mechanical properties of polymer composites can be tuned using different percentages and different kind of fillers: either low-cost (e.g., carbon black), ecofriendly (e.g., biochar), or sophisticated (e.g., carbon nanotubes). In this work, the mechanical and electrical behavior of composites with biochar and multiwall carbon nanotubes dispersed in epoxy resin are compared. Superior mechanical properties (ultimate tensile strength, strain at break) were noticed at low heat-treated biochar (concentrations 2–4 wt %). Furthermore, dielectric properties in the microwave range comparable to low carbon nanotubes loadings can be achieved by employing larger but manageable amounts of biochar (20 wt %), rending the production of composites for structural and functional application cost-effective.

Preparation and Performance of PVC/CNT Nanocomposite

ABSTRACTThe PVC/CNT nanocomposite was prepared with commercial poly(vinyl chloride) (PVC) beads and multiwall carbon nanotube (CNT). The comparative values of the electromagnetic interference shielding effectiveness (EMI SE) and electrical conductivity of PVC/CNT nanocomposite in the presence and absence of PVC beads were described. The results showed that the EMI SE values and electrical conductivity values of PVC/CNT nanocomposite had increased compared to those without PVC beads. After the addition of PVC beads, both values of the EMI SE and electrical conductivity had also increased with the increasing of the amount of PVC bead on the PVC/CNT nanocomposite, and the PVC/CNT nanocomposite in the presence of PVC bead showed high EMI SE value (22.6 dB at 4.0 wt% CNT loading in the presence of 70 wt% bead) and high conductivity value (5.31×10−2S cm−1 at 1.0 wt% CNT loading in the presence of 70 wt% bead) at low CNT loading. Thus, PVC beads effectively play a major role in enhancing the EMI SE value and electrical conductivity value of the nanocomposite. To check the bead region and solvent‐dried CNT region in the nanocomposite, morphological studies have been done and morphological studies of the PVC/CNT nanocomposite supported the two‐phase regions in the composite and the selective dispersion of the CNT in the solvent‐dried phase has been clearly observed.

Hotmelts with improved properties by integration of carbon nanotubes

With the aim of the development of conductive and mechanically improved adhesives, carbon nanotubes (CNTs) were dispersed by melt mixing into a non-reactive polyolefine based hotmelt adhesive. The composite materials, containing 0.5 to 5.0wt% multi-walled CNTs (MWNTs), showed electrical percolation at about 0.75wt%. Investigations of the mechanical properties using tensile tests resulted in a significant enhancement of Young's modulus up to 372% and nearly doubling of tensile strength at 5.0wt%. Even if the hotmelt material is highly elastic compared to typical thermoplastic matrices, the melt mixing resulted in suitable CNT dispersion. The melt viscosity increased with CNT loading, however near the observed electrical percolation threshold the processability was not notably reduced. Most important, next to conductivity at low CNT loadings, also a significant enhancement in the shear strength of bonded joints of AlMg3 up to values of 250% of the pure hotmelt could be obtained. The property profile can be tailored with CNT concentration, indicating the suitability of CNT addition into these hotmelt adhesives.

Indentation size effect and wear characteristics of spark plasma sintered, hard MWCNT/Al2O3 nanocomposites

Magnesia doped multiwalled carbon nanotube (CNT)/α-alumina nanocomposites have been fabricated by spark plasma sintering at 1500°C under 50 MPa in argon. Owing to combined grain refining effect of nanotube and magnesia, nanocomposites possessed smaller matrix grains and extensively lower matrix crystallites than pure alumina. Thermal expansion mismatch between matrix and filler rendered up to four times higher compressive lattice microstrain to the nanocomposites over pure alumina. Despite very low CNT loading (e.g. 0·13 wt-%), nanocomposites offered considerably higher hardness (as high as 24·42 GPa), negligible indentation size effect (Meyer exponent = 1·906 − 1·941) and enhanced elastic response over pure alumina. Up to 0·27 wt-% nanotube loading, much higher wear resistance was observed for the nanocomposites over pure alumina. The presence of uniformly dispersed and structurally intact nanotubes coupled with lower matrix grains and crystallites having compressive lattice strain were the key factors behind achieving such improved mechanical properties of the present nanocomposites.

Electrically conductive polypropylene nanocomposites with negative permittivity at low carbon nanotube loading levels.

Polypropylene (PP)/carbon nanotubes (CNTs) nanocomposites were prepared by coating CNTs on the surface of gelated/swollen soft PP pellets. The electrical conductivity (σ) studies revealed a percolation threshold of only 0.3 wt %, and the electrical conductivity mechanism followed a 3-d variable range hopping (VRH) behavior. At lower processing temperature, the CNTs formed the network structure more easily, resulting in a higher σ. The fraction of γ-phase PP increased with increasing the pressing temperature. The CNTs at lower loading (0.1 wt %) served as nucleating sites and promoted the crystallization of PP. The CNTs favored the disentanglement of polymer chains and thus caused an even lower melt viscosity of nanocomposites than that of pure PP. The calculated optical band gap of CNTs was observed to increase with increasing the processing temperature, i.e., 1.55 eV for nanocomposites prepared at 120 °C and 1.70 eV prepared at 160 and 180 °C. Both the Drude model and interband transition phenomenon have been used for theoretical analysis of the real permittivity of the nanocomposites.

Improved fracture toughness and integrated damage sensing capability by spray coated CNTs on carbon fibre prepreg

The development of a hierarchically engineered micro-nano hybrid composite system is described. A spray coating technique has been utilized as an effective way to deposit carbon nanotubes (CNTs) onto carbon fibre prepregs with good control of network formation and the potential for localization. Compared to more traditional approaches of introducing CNTs into epoxy matrices for enhancing composite properties, this technique has benefits in terms of its simplicity and versatility, as well as the potential for industrial scale-up. The effectiveness of the technique is demonstrated by the extremely low CNT loading (0.047wt.%) needed to significantly increase the Mode-I fracture toughness of the carbon fibre laminates by about 50%, which is so far the largest reported improvement for such extremely low concentrations of non-functionalized CNTs. In-situ damage sensing has also been presented for the monitoring of structural health of these nano-engineered composite laminates upon loading, and a systematic analysis of sensing signals is performed.

Alignment and Surface Modification of Multiwall Carbon Nanotubes Polymeric Composites

Polymer matrices add carbon nanotubes have significantly improved mechanical and electrical properties at very low carbon nanotube loading. That mechanical and electrical properties of aligned composites are better than those of random ones has been demonstrated in past studies. The non-conductive barriers of surface contaminants and weakly bound polymer layers will deform on the surface of composite resulted from the effects of micro gravity and oxidization. Addition of the adaptive plasma modification makes improvement in the surface properties of the composites is necessary. In this study, we actively align and network multiwall carbon nanotubes (MWCNTs) in a polymer matrix, then adopt O2/CF4radio frequency (RF) plasma to modify the surface of polymeric composite. MWCNTs were aligned using an AC electric field to elicit dipolar interactions among the nanotubes in a viscous matrix following immobilization by curing under continuous application of an anisotropic electric field, and the barriers of surface contaminants and weakly bound polymer layers can be reduced to the smallest degree or eliminated by RF plasma modification. Consequently, the MWCNTs polymeric composite amplify the flexural modulus, wear resistance, and electrical conductivity in the reality.

Effect of carbon nanotubes dispersion on morphology, internal structure and thermal stability of electrospun poly(vinyl alcohol)/carbon nanotubes nanofibers

The current work reports the effect of multi walled carbon nanotubes and single walled carbon nanotubes dispersion on morphological, structural and thermal degradation of electrospun poly(vinyl alcohol) (PVA)/carbon nanotubes (CNTs) dispersed in sodium dodecyl sulfate (SDS) (PVA/CNTs–SDS) composites nanofibers. (PVA/CNTs–SDS) nanocomposites fibers were elaborated using the traditional electrospinning process to disperse and align CNTs into the fibers, especially for low CNTs loading fraction: 0.3 and 0.7 wt%. The morphology of the electrospun fibers was studied using the scanning electronic microscopy. The average diameter of the fibers changes significantly after the incorporation of the CNTs in the PVA. Furthermore, Fourier transform infrared spectroscopy elucidated the effect of CNTs on the crystallization of the PVA which was confirmed by X-ray diffraction analysis. Thermogravimetric analysis showed that the thermal stability of the composite fibers depends on the loading fraction and on the type of carbon nanotubes.

A facile route to develop electrical conductivity with minimum possible multi‐wall carbon nanotube (MWCNT) loading in poly(methyl methacrylate)/MWCNT nanocomposites

AbstractToday, we stand at the threshold of exploring carbon nanotube (CNT) based conducting polymer nanocomposites as a new paradigm for the next generation multifunctional materials. However, irrespective of the reported methods of composite preparation, the use of CNTs in most polymer matrices to date has been limited by challenges in processing and insufficient dispersability of CNTs without chemical functionalization. Thus, development of an industrially feasible process for preparation of polymer/CNT conducting nanocomposites at very low CNT loading is essential prior to the commercialization of polymer/CNT nanocomposites. Here, we demonstrate a process technology that involves in situ bulk polymerization of methyl methacrylate monomer in the presence of multi‐wall carbon nanotubes (MWCNTs) and commercial poly(methyl methacrylate) (PMMA) beads, for the preparation of PMMA/MWCNT conducting nanocomposites with significantly lower (0.12 wt% MWCNT) percolation threshold than ever reported with unmodified commercial CNTs of similar qualities. Thus, a conductivity of 4.71 × 10−5 and 2.04 × 10−3 S cm−1 was achieved in the PMMA/MWCNT nanocomposites through a homogeneous dispersion of 0.2 and 0.4 wt% CNT, respectively, selectively in the in situ polymerized PMMA region by using 70 wt% PMMA beads during the polymerization. At a constant CNT loading, the conductivity of the composites was increased with increasing weight percentage of PMMA beads, indicating the formation of a more continuous network structure of the CNTs in the PMMA matrix. Scanning and transmission electron microscopy studies revealed the dispersion of MWCNTs selectively in the in situ polymerized PMMA phase of the nanocomposites. Copyright © 2012 Society of Chemical Industry

Aligned MWCNT-Reinforced Bulk Epoxy-Matrix Composites by Dielectrophoretic Force

Studies have proved that enhancing epoxy matrices by adding carbon nanotubes to form structural reinforcements has significantly improved mechanical properties at very low carbon nanotube loading. That mechanical properties of aligned composites are better than those of random ones has been demonstrated in past studies; however, alignment is not easy to achieve in carbon nanotube epoxy-matrix bulk composite by conventional techniques. In this study, epoxy-matrix bulk composites reinforced by aligned multi-walled carbon nanotubes (MWCNTs) are prepared using an RF electric field to elicit dipolar interactions among the nanotubes in a viscous matrix following immobilization by curing under continuous application of an anisotropic electric field and the fracture toughness is experimentally characterized later. The processes of actively aligned MWCNTs epoxy-matrix bulk composite were controlled as a function of CNT weight fraction, the frequency of dielectrophoretic field and processing time. Carbon nanotubes are not only aligned along the field but also migrate laterally to enhance thickness. Eventually, addition of nanotubes improved the mechanical properties of the MWCNT/epoxy bulk composites, and the increase in the flexural modulus and fracture toughness with the aligned nanotube composite is two times greater than the improvement for the randomly oriented composite.

ULTRASONIC AIDED EXTRUSION OF CNT- AND CNF-FILLED SBR COMPOUNDS AND PROPERTIES OF THEIR VULCANIZATES

Abstract Ultrasonically assisted single screw extrusion of styrene–butadiene rubber (SBR) compounds filled with multiwall carbon nanotubes (CNT) up to 20 phr and carbon nanofibers (CNF) up to 35 phr was carried out. The effects of ultrasonic amplitude on processing characteristics, rheology, extractable amount, vulcanization behavior, mechanical properties, abrasion, electrical resistivity, and morphology were investigated. Ultrasonically treated compounds showed an increase in viscosity and unextractable content in both CNT- and CNF-filled compounds. A decrease in the induction time of curing with amplitude was observed in CNT-filled compounds. However, the induction time of CNF-filled compounds showed more complex behavior with amplitude. The final cure torque, crosslink density, modulus, and tensile strength showed a maximum at an intermediate amplitude in filled vulcanizates. An increase in the glass transition temperature (Tg) and a decrease in tan δ at Tg with amplitude were observed in CNF- and CNT-filled vulcanizates. At the same time, tan δ in the range of 0–60 °C of these vulcanizates showed, respectively, a minimum and a continuous increase with amplitude. CNF-filled vulcanizates exhibited improved abrasion resistance with optimum results at an amplitude of 5.0 μm. The effect diminished with increasing CNF loadings. Improvements in abrasion resistance of CNT-filled vulcanizates were observed at certain amplitudes at low CNT loadings only. Ultrasonic treatment caused a significant reduction in the electrical percolation threshold of CNF- and CNT-filled vulcanizates. Atomic force microscope analysis showed a generation of unique CNT agglomerates by ultrasonic treatment, suggesting an increase of rubber–filler interaction. High resolution scanning electron microscopy analysis of vulcanizates showed better dispersion of ZnO by ultrasonic treatment.