Aggregation Of Multi-walled Carbon Nanotubes Research Articles

Stability of multi-walled carbon nanotube+laponite hybrid particles in aqueous suspensions

Abstract Aggregation of multi-walled carbon nanotube (NT) + laponite hybrid particles in aqueous suspensions under continuous stirring at different values of mass ratio of laponite and NTs, X = m L / m NT , was investigated using Photometric Dispersion Analyser. It has been found that NTs + laponite suspension at X = 1 is the most stable in respect to variation of pH and electrolytes concentration. Addition of electrolytes (KCl, CaCl 2 and AlCl 3 ) destabilized the suspension with formation of large quickly sedimenting flocs. Also the strength of flocs and the reversibility of aggregation of NT + laponite nanoparticles as a function of the shear rate have been determined. From time dependencies of the degree of aggregation in hybrid NTs + laponite suspensions, the critical coagulation concentrations (CCC) for KCl (CCC 1 = 5 × 10 −3 M), CaCl 2 (CCC 2 = 10 −3 M) and AlCl 3 (CCC 3 = 10 −5 M) for the NTs + laponite complex suspension were estimated. The ratio of CCC 1 /CCC 2 ≈ 5 is very close to the CCC z 2.5 = 5.66 criterion. It is an evidence of aggregation of NT + laponite hybrid particles in the secondary minimum.

High resolution and dynamic imaging of biopersistence and bioreactivity of extra and intracellular MWNTs exposed to microglial cells

Multi-walled carbon nanotubes (MWNTs) are increasingly being developed both as neuro-therapeutic drug delivery systems to the brain and as neural scaffolds to drive tissue regeneration across lesion sites. MWNTs with different degrees of acid oxidation may have different bioreactivities and propensities to aggregate in the extracellular environment, and both individualised and aggregated MWNTs may be expected to be found in the brain. Before practical application, it is vital to understand how both aggregates and individual MWNTs will interact with local phagocytic immune cells, the microglia, and ultimately to determine their biopersistence in the brain. The processing of extra- and intracellular MWNTs (both pristine and when acid oxidised) by microglia was characterised across multiple length scales by correlating a range of dynamic, quantitative and multi-scale techniques, including: UV–vis spectroscopy, light microscopy, focussed ion beam scanning electron microscopy and transmission electron microscopy. Dynamic, live cell imaging revealed the ability of microglia to break apart and internalise micron-sized extracellular agglomerates of acid oxidised MWNTs, but not pristine MWNTs. The total amount of MWNTs internalised by, or strongly bound to, microglia was quantified as a function of time. Neither the significant uptake of oxidised MWNTs, nor the incomplete uptake of pristine MWNTs affected microglial viability, pro-inflammatory cytokine release or nitric oxide production. However, after 24 h exposure to pristine MWNTs, a significant increase in the production of reactive oxygen species was observed. Small aggregates and individualised oxidised MWNTs were present in the cytoplasm and vesicles, including within multilaminar bodies, after 72 h. Some evidence of morphological damage to oxidised MWNT structure was observed including highly disordered graphitic structures, suggesting possible biodegradation. This work demonstrates the utility of dynamic, quantitative and multi-scale techniques in understanding the different cellular processing routes of functionalised nanomaterials. This correlative approach has wide implications for assessing the biopersistence of MWNT aggregates elsewhere in the body, in particular their interaction with macrophages in the lung.

Effect of the degree of crystallinity on the electrical properties of MWCNT filled poly (ethylene-co-ethyl acrylate)/LDPE blend composites prepared by melt mixing

Poly(ethylene-co-ethyl acrylate) (EEA)/multiwalled carbon nanotubes (MWCNTs) master batches are prepared via melt mixing to investigate the effect that blending low density polyethylene (LDPE) into the master batch has on their electrical properties. Blending LDPE into the EEA/MWCNT master batches with a relatively low ratio of LDPE to EEA improves the electrical conductivity and lowers the percolation threshold as a result of the increase in the dielectric constant of EEA/LDPE blend resin and a better dispersion of MWCNTs. The electrical conductivity of the blend composite peaks at 20% LDPE and is inversely proportional to the degree of crystallinity of the composite. The average size and the number of the MWCNT aggregates decreases after LDPE blending, thus the better distribution is obtained for the MWCNTs without disturbing the formation of conducting paths caused by the presence of crystallites.

DNA-Assisted Solubilization of Carbon Nanotubes and Construction of DNA-MWCNT Cross-Linked Hybrid Hydrogels.

A simple method for preparation of DNA-carbon nanotubes hybrid hydrogel based on a two-step procedure including: (i) solubilization of multi-walled carbon nanotubes (MWCNT) in aqueous solution of DNA, and (ii) chemical cross-linking between solubilized MWCNT via adsorbed DNA and free DNA by ethylene glycol diglycidyl ether is reported. We show that there exists a critical concentration of MWCNT below which a homogeneous dispersion of MWCNT in hybrid hydrogel can be achieved, while at higher concentrations of MWCNT the aggregation of MWCNT inside hydrogel occurs. The strengthening effect of carbon nanotube in the process of hydrogel shrinking in solutions with high salt concentration was demonstrated and significant passivation of MWCNT adsorption properties towards low-molecular-weight aromatic binders due to DNA adsorption on MWCNT surface was revealed.

Study of the influence of multiwalled carbon nanotubes (12–14 nm) on the main target tissues of the bivalve Modiolus modiolus

The reaction of bivalves Modiolus modiolus to pulse (for 24 and 48 h) exposure with multiwalled carbon nanotubes (MWCNTs) (12–14 nm, MWNT concentration in sea water of 100 mg/L) is manifested in the ingestion of MWCNT aggregates formed in seawater despite their rapid sedimentation from the water column to the bottom of the aquariums. After 24 h, the MWCNT aggregates are observed in the intestinal lumen (size of 10 to 150 μm) and in the tubules of the digestive gland (10 to 50 μm). After 48 h, only large aggregates in contact with mucus and desquamated epithelium fragments are detected in the lumen of the intestine. The smallest aggregates seem to be inside epithelial cells. In the intestine, digestive gland, and gills, MWCNT aggregates induce histopathological changes in the epithelium (erosion, necrosis, trend towards increased vacuolization of the cells) and swelling of the connective tissue. In the gill epithelium after 48 h, patterns morphologically corresponding to apoptosis are observed. Despite significant organ damage, no change in the cellular composition of the hemolymph in mussels exposed to the MWCNTs is found.

Dispersion of Multiwall Carbon Nanotubes in Organic Solvents through Hydrothermal Supercritical Condition

Multiwall carbon nanotube (MWCNT) composite materials require careful formulation of processing methods to ultimately realize the desired properties. Until now, controlled dispersion of MWCNT remains a challenge, due to strong van der Waals binding energies associated with the MWCNT aggregates. In the present study, an effort has been made to disperse MWCNTs in organic solvents like dichloromethane, ethanol, isopropyl alcohol, and hexane through hydrothermal reaction. Dichloromethane is considered the best solvent for the dispersion of MWCNTs. The characterizations were carried out to find the dispersion design, particle size, and stabilization, which clearly indicate that the desired properties of MWCNTs have been achieved.

Identifying contact-mediated, localized toxic effects of MWCNT aggregates on epithelial monolayers: a single-cell monitoring toxicity assay

Aggregates of multiwalled carbon nanotubes (MWCNT) impair the barrier properties of human airway cell monolayers. To resolve the mechanism of the barrier alteration, monolayers of Calu-3 human airway epithelial cells were exposed to aggregated MWCNT. At the cell-population level, trans-epithelial electrical resistance (TEER) was used as an indicator of barrier competence, caspase activity was assessed with standard biochemical assays, and cell viability was investigated by biochemical techniques and high-throughput screening (HTS) technique based on automated epifluorescence microscopy. At cell level, the response to MWCNT was investigated with confocal microscopy, by evaluating cell death (calcein/propidium iodide (PI)), proliferation (Ki-67), and apoptosis (caspase activity). At the cell-population level, exposure to aggregated MWCNT caused a decrease in TEER, which was not associated with a decrease in cell viability or onset of apoptosis even after an 8-d exposure. In contrast, confocal imaging demonstrated contact with MWCNT aggregates triggered cell death after 24 h of exposure. In the presence of a natural surfactant, both TEER decrease and contact-mediated toxicity were mitigated. With confocal imaging, increased proliferation and apoptosis were detected in Calu-3 cells next to the aggregates. Contact-mediated cytotoxicity was recorded in two additional cell lines (BEAS-2B and A549) derived from human airways. Similar results were confirmed by adopting two additional MWCNT preparations with different physico-chemical features. This indicates MWCNT caused localized damage to airway epithelial monolayers in vitro and altered the apoptotic and proliferative rate of epithelial cells in close proximity to the aggregates. These findings provide evidence on the pathway by which MWCNT aggregates impair airway barrier function, and support the use of imaging techniques as a possible regulatory-decision supporting tool to identify effects of aggregated nanomaterials not readily detected at cell population level.

Electrical percolation, morphological and dispersion properties of MWCNT/PMMA nanocomposites

Nanocomposites of poly (methyl methacrylate) (PMMA) and carbon nanotubes have a high potential for applications where conductivity and low specific weight are required. This piece of work concerns investigations of the level of dispersion and morphology on the electrical properties of in situ polymerized nanocomposites in different concentrations of multi-walled carbon nanotubes (MWCNT) in a PMMA matrix. The electrical conductivity was measured by the four point probe. The morphology and dispersion was analyzed by Transmission Electron Microscopy (TEM) and Small Angle X-ray Scattering (SAXS). The correlation between electrical conductivity and the MWCNT amount, presented a typical percolation behavior, whose electrical percolation threshold determined by power law relationship was 0.2 vol. (%) The exponent t from the percolation power law indicated the formation of a 3D network of randomly arranged MWCNT. SAXS detected that the structures are intermediate to disks or spheres indicating fractal geometry for the MWCNT aggregates instead of isolated rods. HR-TEM images allowed us to observe the MWCNT individually dispersed into the matrix, revealing their distribution without preferential space orientation and absence of significant damage to the walls. The combined results of SAXS and HR-TEM suggest that MWCNT into the polymeric matrix might present interconnected aggregates and some dispersed single structures.

Release Kinetics of Multiwalled Carbon Nanotubes Deposited on Silica Surfaces: Quartz Crystal Microbalance with Dissipation (QCM-D) Measurements and Modeling

Understanding the kinetics of the release of carbon nanotubes (CNTs) from naturally occurring surfaces is crucial for the prediction of the environmental fate and transport of CNTs. In this study, the release kinetics of multiwalled CNTs (MWNTs) from silica surfaces was investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D). MWNTs were first deposited on silica surfaces under favorable deposition conditions (1.50 mM CaCl2 and pH 7.1) and the deposited MWNTs were then rinsed at different electrolyte solutions to induce the release of MWNTs from the primary energy minimum. The kinetics of MWNT release was shown to be first order with respect to the deposited MWNTs when complete release took place. A model that accounts for the releasable and unreleasable components of MWNTs was used to fit the experimental data in order to derive the release rate coefficients. When the CaCl2 concentration in the eluent was decreased, a larger fraction of deposited MWNTs was released and the release rate coefficient of the releasable MWNTs also increased. The rise in the surface charges of both MWNTs and silica surfaces with the drop in CaCl2 concentration likely resulted in the decrease in the height of the energy barrier, thus facilitating the release of the nanotubes. Moreover, when the initial surface concentrations of deposited MWNTs were over 1000 ng/cm(2), the release rate coefficient was lower than expected. The reduced release kinetics was likely due to the formation of large surface-bound MWNT clusters which had considerably lower diffusion coefficients than dispersed MWNTs or MWNT aggregates.

Functionalization of MWCNT with P(MMA-co-S) copolymers via ATRP: Influence on localization of MWCNT in SAN/PPE 40/60 blends and on rheological and dielectric properties of the composites

In this work, the localization of functionalized multi-walled carbon nanotubes (MWCNT) with random copolymers of methyl methacrylate and styrene (P(MMA-co-S)) in poly(styrene-co-acrylonitrile)/poly(2, 6-dimethyl-1,4-phenylene ether) blends (SAN/PPE) and its influence on morphological, rheological and dielectric properties of the composites were investigated. P(MMA-co-S) copolymers were grafted onto MWCNT via atom transfer radical polymerization (ATRP). The molecular weight of the copolymers was adjusted by controlling the time of reaction. In SAN/PPE blends, MWCNT grafted with low molecular weight copolymers were predominantly located at the interface of the blend and a few individual tubes were dispersed in the PPE phase. Aggregation of MWCNT was observed nearby the interfacial region because of micellization of grafted copolymers. Aggregation was more pronounced with increasing molecular weight of the grafted P(MMA-co-S) copolymer. In the melt, the composite containing MWCNT with low molecular weight copolymers had higher dynamic moduli than the one with pristine MWCNT. An increasing molecular weight of grafted copolymer led to a softening effect which resulted in a reduction of the moduli of the composite. Although a pronounced enhancement was observed for the composites with pristine MWCNT, only a small increase in electrical conductivity was achieved by adding functionalized MWCNT owing to the poor network formed by functionalized MWCNT in the blends.

Dispersion of multi-walled carbon nanotube using soluble polysilsesquioxane containing alkylammonium side chains and triiodide counterions

In this study, we found that 1-pentanol dispersion of multi-walled carbon nanotube (MWCNT) was obtained when ultrasonication of MWCNT was performed in 1-pentanol solution of ammonium group-containing polysilsesquioxane with triiodide anions (PSQ-I3). Dispersibility of MWCNT in 1-pentanol was first investigated by the presence of absorption at 750 nm in UV–Vis measurements. In addition, the number-average particle size estimated by dynamic light scattering measurement of 1-pentanol dispersion of MWCNT/PSQ-I3 was assessed to be 120.3 ± 34.8 nm. The dispersion passed through a membrane filter with ca. 7 μm pores, indicating that large MWCNT aggregates in micrometer scale did not exist in 1-pentanol. Furthermore, the transmission electron microscopy image of the sample obtained by drying 1-pentanol dispersion of MWCNT/PSQ-I3 showed many lines with ca. 10 nm diameter derived from MWCNT, indicating that MWCNTs were individually dispersed in PSQ matrix.

Studies on synthesis and characterization of multi-walled carbon nanotube-reinforced polyimide nanocomposites based on a siloxane-modified anhydride

A novel series of multi-walled carbon nanotube (MWCNT) reinforced siloxane dianhydride based polyimide (PI) nanocomposites were designed and developed using in situ polymerization approach via thermal imidization. The polyamic acid obtained from the reaction of siloxane dianhydride and pyridine diamine/ p-phenylenediamine was then incorporated with varying percentages of MWCNTs, which then undergoes thermal imidization to form MWCNT-PI nanocomposites. The synthesized PIs were then characterized using analytical methods. From thermal analysis, it can be seen that the glass transition temperature increased significantly by incorporating acid functionalized MWCNTs into the PI matrix than that of neat PI. This is due to the constraint effect of MWCNTs as well as the reduction in the movement of polymer chains. It exhibits an increased dielectric constant with the increase in weight percentage of MWCNTs to PI matrix. No aggregation and homogeneous dispersion of MWCNTs throughout the PI matrix have been achieved as evidenced by scanning electron microscopy and transmission electron microscopy. The newly designed PI system is responsible for the significant improvement of dispersion, thus enhancing attractive flame retardancy and dielectric properties.

Perfect High‐Temperature Plasticity Realized in Multiwalled Carbon Nanotube‐Concentrated α‐Al2O3 Hybrid

We investigate the high‐temperature compressive deformation behavior of a novel, fully dense and structurally uniform, 20 vol% multiwalled carbon nanotube (MWCNT)–α‐Al2O3 matrix hybrid, which has a strong room‐temperature interfacial shear resistance (ISR) and a unique MWCNT‐concentrated grain‐boundary (GB) structure. We realized a perfect plastic deformation at 1400°C and a rather high initial strain rate of 10−4 s−1 by a low ~30 MPa flow stress, which is contrary to the strain hardening response of fine‐grain monolithic Al2O3. This unique performance in CNT–ceramic system in compression is explained as follows: the concentrated network of individual MWCNTs perfectly withstands the high‐temperature and shear/compressive forces, and strongly preserves the nanostructure of Al2O3 matrix by preventing the dynamic grain growth, even during a large ~44% deformation. Furthermore, the presence of large amount of radially soft/elastic, highly energy‐absorbing MWCNTs in the GB and specially multiple junction areas, and a potentially weak 1400°C‐ISR, could greatly facilitate the GB sliding process (despite the hybrid's strong room‐temperature ISR), as evidenced by the formation of some submicrometer‐scale MWCNT aggregates in GB area, the equiaxed grains and dislocation‐free nanostructure of the deformed hybrid. The results presented here could be attractive for the ceramic forming industry and could be regarded as a reference for oxide systems in which, the GB areas are occupied with soft/elastic, highly energy‐absorbing nanostructures.

Influences of perfluorooctanoic acid on the aggregation of multi-walled carbon nanotubes

The aggregation of multi-walled carbon nanotubes (MWCNTs) in the aqueous phase not only inhibits their extensive utilization in various aspects but also dominates their environmental fate and transport. The role of surfactants at low concentration in the aggregation of MWCNTs has been studied, however the effect of perfluorinated surfactants at low concentration is uncertain. To understand this interfacial phenomenon, the influences of perfluorooctanoic acid (PFOA), and sodium dodecyl sulfate (SDS) as a control, on MWCNT aggregation in the aqueous phase were examined by the UV absorbency method. Influences of pH and cationic species on the critical coagulation concentration (CCC) value were evaluated. The CCC values were dependent on the concentration of PFOA, however a pronounced effect of SDS concentration on the CCC values was not observed. The CCC values of the MWCNTs were 51.6 mmol/L in NaCl and 0.28 mmol/L in CaCl2 solutions, which suggested pronounced differences in the effects of Na+ and Ca2+ ions on the aggregation of the MWCNTs. The presence of both PFOA and SDS significantly decreased the CCC values of the MWCNTs in NaCl solution. The aggregation of the MWCNTs took place under acidic conditions and was not notably altered under neutral and alkaline conditions due to the electrostatic repulsion of deprotonated functional groups on the surface of the MWCNTs.

Effect of the synthetic strategy on the non-covalent functionalization of multi-walled carbon nanotubes with polymerized ionic liquids

Multiwalled carbon nanotubes (MWCNTs) have been non covalently functionalized with various imidazolium-based polymerized ionic liquids (PILs). Two functionalization methods, starting from ionic liquid (IL) monomers containing a vinyl group, have been explored: a simple solution mixing of MWCNTs and PILs and the in situ polymerization. The resulting hybrid materials have been characterized by infrared and Raman spectroscopy, transmission electron microscopy, zeta potential measurement, thermogravimetric analysis and differential scanning calorimetry, and their dispersibility in various solvents has been evaluated to access the effect of the functionalization. The particle size analysis of MWCNTs/PILs agglomerates in various solvents is also reported. The in situ method allows a homogeneous coating of the MWCNT surface and thus a better dispersion of the nanotubes. The solution mixing method, for which diffusion limitations of the PILs into MWCNT aggregates should exist, does not allow a uniform surface functionalization. Finally, with protic IL monomers showing a tendency for hydrogen bonding, we have produced stable CNT/PIL organo- or hydrogel composites.

Equilibrium, Kinetic, and Thermodynamic Studies on the Adsorption of Triclosan onto Multi‐Walled Carbon Nanotubes

AbstractThe increased accumulation of toxic pharmaceuticals and personal care products in the environment is a concern of worldwide relevance. Efficient technologies are needed to mitigate the level of such chemicals in natural waters. The suitability of multi‐walled carbon nanotubes (MWCNTs) to remove aqueous triclosan (a widely used anti‐microbial agent) was investigated in the present study. Tested operational parameters included the pH (3.0–11.0) value and the ionic strength (10−3, 10−2, and 10−1 M). Kinetic and thermodynamic studies were conducted at different initial concentrations (4, 8, and 10 mg/L) and temperatures (288, 298, and 308 K). Results showed higher triclosan adsorption at pH 3.0 (157.7 mg/g) than at pH 11.0 (103.9 mg/g). With an increase of ionic strength from 10−3 to 10−2 M, the adsorption capacity increased from 136.1 to 153.1 mg/g and from 80.8 to 105.8 mg/g at pH 3.0 and 10.0, respectively, while further increase of ionic strength to 10−1 M slightly reduced the triclosan adsorption to 149.9 and 94.7 mg/g due to the aggregation of MWCNTs. The Polanyi–Manes model (PMM) provided a best fitting of adsorption isotherms to the experimental data, and the kinetic process was well described by the pseudo second‐order kinetic model. The calculated thermodynamic parameters (ΔH0 = −88.08 kJ/mol, ΔS0 = −173.38 J/mol K) suggested that the adsorption of triclosan is spontaneous and exothermic in nature. The findings of the present work have significant implications for the removal of triclosan from aqueous solution with MWCNTs.

Electrochemical Synthesis and Characterization of Multi-walled Carbon Nanotubes/Polypyrrole and Polypyrrole Hollow Nanotubes

We report the electrochemical synthesis and characterization of hybrid structures composed by hollow nanotubes of polypyrrole and core-shell composites of multi-walled carbon nanotubes (MWCNTs) coated by polypyrrole (PPy). The synthesis of these systems is critically dependent on relative concentration of carbon nanotubes (introduced as a template for polymerization) and affects the level of conductivity of media, the diameter and relative roughness of synthesized nanotubes. The competition induced by polymerization on the surface of different templates (aggregates of methyl orange and MWCNT) allows that smooth structures can be obtained, minimizing the synthesis of granules of polypyrrole, in a process that affects the morphology, thermal and electrical properties of synthesized materials. As a result, the impedance of mixed composite is lower than the other obtained for each system (MWCNT and hollow nanotubes of PPy), in an indication that synergistic interaction is favored during the synthesis.

Cellulose nanofibers/multi-walled carbon nanotube nanohybrid aerogel for all-solid-state flexible supercapacitors

In recent years, much effort has been dedicated to achieve environmentally friendly, low cost, and excellent performance energy storage devices. In this work, cellulose nanofibers (CNFs)/multi-walled carbon nanotubes (MWCNTs) hybrid aerogels are prepared from CNFs/MWCNTs hydrogels by supercritical CO2 drying using CNFs as an effective, environmentally friendly, and steady dispersant of MWCNTs. All-solid-state flexible supercapacitors are fabricated using CNFs/MWCNTs hybrid aerogel film as the electrode material and charge collector. One-dimensional CNFs can effectively prevent the aggregation of MWCNTs, significantly enhance the re-wettability, and improve the utilization efficiency of the mesopores. Therefore, CNFs/MWCNTs hybrid aerogel film-based all-solid-state flexible supercapacitors exhibit excellent electrochemical properties: the specific capacitance is about 178 F g−1. The flexible supercapacitors also exhibit excellent cyclic stability. Our work provides a novel method using low cost, and environmentally friendly CNFs to realize the full potential of the MWCNTs in an assembled bulk form. Taking its low cost and environmentally friendliness, CNFs/MWCNTs hybrid aerogel has great potential as the electrode material for all-solid-state flexible supercapacitors.

Grinding Effect of Rotation Speed on the Surface Changes of Multi-Walled Carbon Nanotubes and Their Dispersion Ability

The present work provides basic insight to largely improving the dispersion of treated multi-walled carbon nanotubes in aqueous solution with grinding and ultrasonication. The present study consists of dry and wet grinding of multi-walled carbon nanotubes with rotation speeds of 200, 300, 400 and 500 rpm and both type of grinding with highest rotation speeds assisted to ultra-sonication dispersion of multi-walled carbon nanotubes in aqueous solutions. A simple method of purifying process also has been discussed in this study. The results demonstrate the grinding method has urgent advantage for dispersion of multi-walled carbon nanotubes in aqueous solution: grinding can break up large multi-walled carbon nanotube aggregates into a number of small aggregates along with exfoliation to individual nanotubes which can easy the work loading of ultrasonication for dispersing multi-walled carbon nanotubes.

Percolation behaviour of polypropylene glycol filled with multiwalled carbon nanotubes and Laponite

The percolation behaviour of the hybrid composites of polypropylene glycol (PPG) filled with multiwalled carbon nanotubes (MWCNTs) and Laponite RD (Lap), or with MWCNTs and organo-modified Laponite (LapO) was studied by wide angle X-ray diffraction (XRD), microscopic image analysis, and electrical conductivity measurements. Cetyltrimethylammoniumbromide (CTAB) was used as an organo-modifier of Laponite. The Lap and LapO were found to have rather different affinity to PPG. XRD data have evidenced finite PPG integration inside Lap and complete exfoliation of LapO stacks in a PPG matrix. In PPG+MWCNT composites containing no Lap or LapO, increase of MWCNT concentration above the critical value Cp∼0.4wt% resulted in percolation. The value of the percolation threshold, Cp, was practically the same for hybrid PPG+MWCNT+Lap composites. However, it noticeably decreased (Cp∼0.2wt%) in PPG+MWCNT+LapO materials. The observed behaviour of the percolation threshold may be attributed to the effects exerted by LapO on the size of MWCNT aggregates, state of their dispersion and homogeneity of their spatial distribution.