Dispersion Of Multi-walled Carbon Nanotubes Research Articles

MWCNT buckypaper disc films as alternative to the drop casting method to modify electrode surfaces

We report the comparison of the modification of glassy carbon electrode (GCE) with multiwalled carbon nanotubes (MWCNTs) and nitroaromatic compounds using two different methodologies, the traditional drop casting (DC) method and an alternative buckypaper disc film (BP) method. The methodology for the construction of the BP disc film electrodes consists of a simple filtration of MWCNT and polystyrene (PS) dispersion in 1,3-dioxolane through a nylon membrane filter and then disc-shaped cutting. The adhesion of the disc film to the GCE is achieved by a direct STAMP process.The electrode surfaces were characterized by Raman spectroscopy (RS), atomic force microscopy (AFM), scanning electron microscopy (SEM) and scanning electrochemical microscopy (SECM) while the electrochemical responses were followed by voltammetry and electrochemical impedance spectroscopy (EIS).The results showed an important enhancement in the reproducibility of the electrochemical response of the electrodes with coefficient of variation (c.v.) values for the faradaic response of 3.82 and 11.42% for the BP and DC methods, respectively. In addition, c.v. values for the capacitive response of 2.2 and 19.2% for the BP and DC methods, respectively. The preparation of BP disc film electrodes improves homogenization in MWCNT deposits causing this increase in the reproducibility of the electrodes.

Fabrication of Low Electrical Percolation Threshold Multi-Walled Carbon Nanotube Sensors Using Magnetic Patterning

Soft robotics is an expanding area with multiple applications; however, building low-cost, soft, and flexible robots requires the development of sensors that can be directly integrated into the soft robotics fabrication process. Thus, the motivation for this work was the design of a low-cost fabrication process of flexible sensors that can detect touch and deformation. The fabrication process proposed uses a flexible polymer nanocomposite with permanent magnets strategically placed where the conductive electrodes should be. The nanocomposite is based on poly(dimethylsiloxane) (PDMS) and multi-walled carbon nanotubes (MWCNTs). The MWCNT contains ferromagnetic impurities remaining from the synthesis process, which can be used for magnetic manipulation. Several electrode geometries were successfully simulated and tested. The magnetic patterning was simulated, allowing the fabrication of conductive patterns within the composite. This fabrication process allowed the reduction of the electrical resistivity of the nanocomposites as compared to the composites with homogeneous MWCNT dispersion. It also allowed the fabrication of piezoresistive and triboelectric sensors at MWCNT concentration as low as 0.5 wt.%. The fabrication process proposed is flexible, allows the development of sensors for soft robotics, as well as monitoring large and unconventional areas, and may be adapted to different mould shapes and polymers at low cost.

Improved Performance of Composite Bipolar Plates for PEMFC Modified by Homogeneously Dispersed Multi-Walled Carbon Nanotube Networks Prepared by In Situ Chemical Deposition

Composite bipolar plates with excellent performance play a crucial role in improving the overall performance of proton-exchange-membrane fuel cells. However, for graphite/resin composite bipolar plates, their electrical conductivity and mechanical properties are often too complex to meet the needs of users at the same time. Although nanoconductive fillers can alleviate this problem, the performance improvement for composite bipolar plates is often limited due to problems such as agglomeration. In this study, a uniformly dispersed multi-walled carbon nanotube network was prepared by in situ vapor deposition on the surface and pores of expanded graphite, which effectively avoided the problem of agglomeration and effectively improved the various properties of the composite BPs through the synergistic effect with graphite. With the addition of 2% in situ deposited carbon nanotubes, the modified composite bipolar plate has the best conductivity (334.53 S/cm) and flexural strength (50.24 MPa), and all the properties can meet the DOE requirements in 2025. Using the in situ deposition of carbon nanotubes to modify composite bipolar plates is a feasible route because it can result in multi-walled carbon nanotubes in large quantities and avoid the agglomeration phenomenon caused by adding nanofillers. It can also significantly improve the performance of composite bipolar plates, achieving the high performance of composite bipolar plates at a lower cost.

Effects of Annealing Temperature and Time on Properties of Thermoplastic Polyurethane Based on Different Soft Segments/Multi-Walled Carbon Nanotube Nanocomposites

Typically, polymer chains can move under the annealing process, resulting in an ordered structure arrangement. This causes an improvement in nanocomposite properties and in the dispersion of filler. In this research, annealed thermoplastic polyurethane (PU)/multi-walled carbon nanotube (MWCNT) nanocomposites were studied to investigate the effect of annealing on the selective dispersion of MWCNTs. PU matrices were composed of two different soft segments, i.e., polyether (PU-Ether) and polyester (PU-Ester). Nanocomposites were prepared by the melt mixing process and annealed at 80 to 120 °C for 6 to 24 h. The increases in annealing time and temperature resulted in microphase separation in segmented PU and the orientation of crystalline structures in the segregated hard domain. Nanocomposites showed higher electrical conductivity after annealing. This implies that the movement of PU chains during heat treatment encouraged the development of the MWCNT network. However, the increase in ordered structures could obstruct the MWCNT network, resulting in lower electrical conductivity levels. Considering the selective dispersion of MWCNT in PU matrices, it was found that MWCNTs dispersed in soft segments of PU-Ether, leading to a significant decrease in elongation at the break after annealing. On the other hand, a decrease in elasticity of PU-Ester nanocomposites was not observed as a result of MWCNT dispersal in hard segments.

Super plasticizer assisted bath ultra sonication for dispersion of multi walled carbon nanotubes in cement composites

This paper presents the observations and findings from an experimental study for dispersion of multiwalled carbon nanotubes (MWCNTs) by bath ultra-sonication in the presence of polycarboxylate ether (PCE) based superplasticizer. Commercial brand of superplasticizer (SP) compatible with cement was adopted for exploring its usage as surfactant during aqueous dispersion of MWCNTs. Cement composite pastes were evaluated for variation in compressive strength and fresh property for a fixed addition percentage of MWCNT. Aqueous dispersion of MWCNTs for incorporation to cement pastes was prepared considering three different sonication process variables; time period of sonication, SP to MWCNT dosage during sonication and temperature of sonication medium. A total of 168 experimental variations were evaluated for compressive strength of resulting cement–carbon nanotubes composite pastes at 7 days age to arrive at an optimal process of bath ultra-sonication with governing variables. Results showed that a sonication time period in the range of 4–5 hours with an SP to MWCNT ratio of 2.5–3 was necessary for satisfactory dispersion of MWCNTs over different temperature ranges of sonication bath medium. Further, the temperature of sonication medium in the range of 35–40°C during aqueous dispersion of MWCNTs was observed to induce noticeable enhancement in strength of composite system indicating improvement in dispersion within an optimal range of sonication medium temperature. Microscopic observations for optimal process variables of dispersion during bath ultra sonication showed evidence of physical changes in MWCNTs from an agglomerated state of particles to separated state.

HEAT-TRANSFER ENHANCEMENT OF MONO ETHYLENE GLYCOL-WATER-BASED SOLAR THERMIC FLUIDS DISPERSED WITH MULTIWALLED CARBON NANOTUBES IN A COILED TUBE HEAT EXCHANGER

The current research focuses on how the inclusion of multiwalled carbon nanotubes (MWCNTs) in mono ethylene glycol-water mixtures affects thermal conductivity, heat transfer, and dynamic viscosity for solar thermal applications. To achieve high stability in mono ethylene glycol-water mixtures, MWCNTs were oxidized and then dispersed at concentrations of 0.5, 0.25, and 0.125 wt.%. Zeta potential analysis was used to track the stability of the nanofluids over a two-month period. With the dispersion of MWCNTs in the base fluids, there is a remarkable increase in thermal conductivity from 15 to 24%. The dynamic viscosity variation is found to be minimal at high temperatures. Heat-transfer studies conducted on a specially designed test rig consisting of a coiled heat exchanger show that ethylene glycol-water mixtures dispersed with MWCNTs exhibit excellent performance under laminar conditions. Correlations for thermal conductivity, dynamic viscosity, and Nusselt number were obtained for all temperature conditions, mass fractions, and percentages of ethylene glycol. In the case of 100% mono ethylene glycol and mono ethylene glycol-water mixtures (90:10 and 80:20) as base fluids, the increase in heat-transfer coefficients of the corresponding nanofluids is up to 30, 26, and 25%, respectively.

Effect of ultrasonication on carboxyl-functionalized multiwalled carbon nanotubes in fresh and hardened Portland cement pastes

abstract: The effects of chemical and physical methods on multiwalled carbon nanotube (MWCNT) dispersion in Portland cement pastes were investigated. Consistency, rheology, compressive strength, dynamic elastic modulus, flexural strength, water absorption, and void content tests were performed to evaluate these effects. Changes in the rheology of the cement pastes and surfactants resulted in a significant reduction in apparent viscosity and yield strength. Additionally, cement pastes containing carboxyl- functionalized MWCNTs (MWCNT-COOH) and surfactant showed higher compressive strengths at 28 d. However, the ultrasonic dispersion method did not significantly influence the properties of hardened Portland cement compared with Portland cement produced using the non-sonicated aqueous solution.

Fabrication of PVA-MWCNT nanocomposite films for UV-shielding applications

Polyvinyl Alcohol (PVA) polymer nanocomposites are incorporated with Multiwall Carbon Nanotubes (MWCNT) of 20 nm diameter by solution casting. The SEM results show uniform dispersion of MWCNTs in the PVA matrix. The glass transition temperature (Tg) and the thermal decomposition temperature of PVA slightly increases with the incorporation of the MWCNTs. The DC electrical conductivity of PVA increases systematically from 4.1 × 10-13 S/cm to 8.1 × 10-8 S/cm for the highest 0.9 wt% MWCNTs. The direct band gap changes from 6.13 to 5.57 eV while the indirect band gap from 5.88 to 5.17 eV, also Urbach energy changes from 0.223 to 0.282 eV as the 0.9 wt% of MWCNTs reinforced in PVA.

Azide‐Modified Poly(diethyl vinylphosphonate) for Straightforward Graft‐to Carbon Nanotube Functionalization

AbstractRare‐earth metal‐mediated group‐transfer polymerization (REM‐GTP) offers distinctive features over common polymerization techniques, such as living character, a broad scope of functional monomers, high activity, excellent control of the polymeric parameters as well as inherent chain‐end functionalization. Through the latter, polymers with reactive end‐groups become feasible, opening the pathway for further post‐polymerization functionalization. In this study, a straightforward graft‐to immobilization of the Michael‐type polymer poly(diethyl vinylphosphonate) (PDEVP) on multi‐walled carbon nanotubes (MWCNT) is reported. Hence, a customized azide initiator is synthesized and studied in the CH bond activation with various lanthanide‐based catalysts and the subsequent polymerization of diethyl vinylphosphonate (DEVP). The successful attachment of the azide end‐group is demonstrated via electrospray ionization mass spectrometry (ESI‐MS) and the synthesized polymers are subjected to immobilization on multi‐walled carbon nanotubes in a graft‐to approach. The prepared MWCNT:PDEVP composites are analyzed via thermogravimetric analysis (TGA), elemental analysis (EA), Raman spectroscopy, X‐Ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) and the versatility of this approach is shown via the stabilization of MWCNT dispersions in water.

Effect of Multi-Walled Carbon Nanotubes (MWCNTs) in Reducing the Corrosion Rate in Cr-MWCNTs Composite Coatings

Carbon steel was coated with Cr-multi-walled carbon nanotube (MWCNTs) coatings via electrodeposition. In this article, the impact of a combination of MWCNTs into the chromium coating on the morphology of the coating surface and corrosion characteristics was inspected. The MWCNTs seem to be evenly distributed across the chromium layer, according to scanning electron microscopy (SEM). Electrochemical measurements were used to conduct corrosion tests on samples of MWCNTs– chromium composite coated and pure chromium coated samples in aqueous NaCl (3.5 wt.%). The outcomes demonstrated a considerable increase in the resistance of corrosion due to the inclusion of MWCNTs during the chromium deposition procedure. In addition, the mechanism of anti-corrosion of the composite coating is also presented. Using an electrolyte bath containing various concentrations of dispersed MWCNTs (0.5, 1, and 1.5 g/L), crack-free and compact coating of Cr-MWCNT composite were electrodeposited on the substrates of the mild steel. The potentiodynamic polarization technique was used to examine the coatings corrosion performance subjected to a 3.5 weight percent of NaCl medium. When compared to chromium coating, the Cr-MWCNT composite coating showed the lowest corrosion rate (1.045x108 mpy) compared to chromium coating (4.891x108 mpy).

Unravelling the sensory capability of MWCNT-reinforced nanocomposites: Experimental and numerical investigations

Multifunctional nanocomposite strain sensors, especially those that contain dispersed multiwall carbon nanotubes (MWCNTs), are known to possess exceptional electrical conductivity. These nano-reinforced composites can be used for structural health monitoring. It is with this in mind that we focus our attention on calibrating the electromechanical behaviour of MWCNT-reinforced epoxy nanocomposites both numerically and experimentally. In particular, our main objective is to unravel the coupled electromechanical behaviour of the conducting composite prior to failure. In the numerical effort, we adopted the effective-medium homogenization and Mori-Tanaka method to account for tunnelling resistance and to predict the sensory capability of the newly developed composite. In the experimental effort, a conductive epoxy nanocomposite containing high quality MWCNTs randomly dispersed within liquid neat epoxy system was developed. The conducting domains of the developed nanocomposite were characterized using atomic force microscope (AFM) measurements. Electromechanical characterisation of the MWCNT-reinforced nanocomposites was also performed using controlled uniaxial tensile tests to evaluate its sensory capability against load. The results of our work reveal: (i) excellent agreement with the micromechanical model, and (ii) the dramatic influence of the concentration of the MWCNTs, their agglomeration and aggregation on the sensory sensitivity of the MWCNT-reinforced epoxy nanocomposite. Interestingly, an increase in the MWCNT filler loading led to a decrease in the sensory sensitivity of the nanocomposite as measured by uniaxial strain gauge factor. The work was further extended to highlight the sources of errors that could lead to erroneous results in developing and calibrating electrically conducting pathways in polymer nanocomposites.

Fabrication of novel buckypaper metal oxide nano-catalysis glycerol carbonate/MWCNTs membrane for efficient removal of heavy metals

This study describes the fabrication of novel buckypaper membranes through the dispersion of multi-walled carbon nanotubes (MWCNTs) in the presence of surfactants metal oxide nano-catalysis Zinc oxide and magnesium oxide (ZnO and MgO) glycerol carbonate separately. Following vacuum filtration of the scattered solutions, self-supporting membranes known as buckypapers (BPs) were produced. The suggested membranes were employed for the efficient removal of heavy metals. The obtained data indicated that the incorporation of both glycerol carbonates prepared by two different nano metal oxides enhanced the permeability of MWCNTs membranes rejection efficiency. The characterization of the synthesized metal oxide nanoparticles, as well as the physicochemical and morphological properties of the membranes, were investigated. The rejection capabilities of membranes for the heavy metal ions were examined. Moreover, the suggested MWCNTs/ZnO nano-catalyst glycerol carbonate BP membrane displayed high rejection efficiency for heavy metals (Cd2+, Cu2+, Co2+, Ni2+, and Pb2+) than that prepared from the MgO nano-catalyst one.

The effect of acid treated multi-walled carbon nanotubes on the properties of cement paste prepared by ultrasonication with polycarboxylate ester

Chemical functionalization of carbon nanotubes by the mix of sulfuric (H2SO4) and nitric (HNO3) acids has been reported to enhance the hydrophilicity of carbon nanotubes, which, in turn, improves its dispersion quality in aqueous solution and within the cement matrix. In this study, multi-walled carbon nanotubes (MWCNT) were treated by a mix of H2SO4 and HNO3, and used for preparation of MWCNT solutions by ultrasonic tip sonication with low amounts of polycarboxylate ester (PCE). The effects of acid functionalization on the dispersion of MWCNT, mechanical performance and hydration of cement paste were studied with respect to changes in MWCNT concentration, ultrasonication time and MWCNT:PCE ratio. According to the experimental results, acid-treated MWCNT contained 13 wt% of carboxyl functional group. The results from Raman spectroscopy showed the increased amount of unadsorbed PCE in solution with acid-treated MWCNT due to the increase in hydrophilicity. Increase in hydrophilicity contributed to a stronger bond between a-MWCNT and cement hydration products, and increased the mechanical strength of cement paste by 55%. The addition of a-MWCNT at 0.1 wt% concentration resulted in the increase of 28-day compressive strength from 40 MPa up to 62 MPa and flexural strength from 4.4 MPa up to 7.6 MPa. Retardation in hydration and increase in porosity were found to be associated with PCE that was not adsorbed on the surface of MWCNT.

Investigation on the enhancement of electromagnetic shielding with efficient use of short carbon fiber inMWCNT‐epoxy nanocomposites

AbstractThe electromagnetic interference (EMI) shielding effectiveness of the epoxy polymer composite reinforced with carbon fiber mat (CFM), short carbon fiber (SCF), and multi‐walled carbon nanotube (MWCNT) is studied in the X‐band (8–12 GHz). Single‐layer unidirectional CFM of 30 wt% epoxy composite with 0° and 90° orientations resulted in EMI shielding of 5 dB and 29.6 dB, respectively. To avoid the influence of CFM orientation on the EMI shielding, SCF of distinct weight percentages (1 and 5 wt%) with fixed weight percentage (1 wt%) of MWCNT are reinforced into epoxy matrix. The EMI shielding provided by 2 mm thick epoxy composite reinforced with 5 wt% SCF along with 1 wt% MWCNT (CNT‐SCF5) is 35.4 dB. The microstructural study revealed uniform dispersion and better adhesion of MWCNT and SCF in the epoxy matrix. The dielectric properties of the fabricated samples indicated an increase in permittivity, electrical tanδ, and conductivity with the grading of SCF and MWCNT. The mechanical properties such as tensile strength and strain of the CNT‐SCF5 showed an increment in ultimate tensile strength and Young's modulus. The homogeneous CNT‐SCF5 epoxy composite with enhanced EMI shielding ability and mechanical properties could be utilized as an efficient EMI shielding material.

A comparative study on nanoparticle network‐dependent electrical conductivity, electromagnetic wave shielding effectiveness and rheological properties in multiwall carbon nanotubes filled polymer nanocomposites

AbstractHerein, a comparative study for the effect of nanoparticle networks on rheological behavior, electrical conductivity, and electromagnetic wave (EMW) shielding effectiveness (SE) is carried in conductive polymer composites (CPC). Two different polymers, that is, poly(ε‐caprolactone) (PCL) and isotactic polypropylene (iPP), which have different dispersion of multiwall carbon nanotubes (MWCNT), are used as polymer matrices. A transmission electron microscope (TEM) and a scanning electron microscope (SEM) are employed to determine the dispersion of MWCNTs in different polymer matrices. A rotational rheometer and a vector network analyzer are used to evaluate the percolation thresholds of storage modulus, complex viscosity and EMW SE, respectively. The results indicate that the EMW SE percolation thresholds are much larger than the electrical and rheological percolation thresholds. Specifically, the percolation thresholds of storage modulus and complex viscosity are 0.39 and 0.33 vol% for the MWCNT/PCL samples, and 1.57 and 1.57 vol% for the MWCNT/iPP samples, respectively. The electrical and EMW SE percolation thresholds are 0.33 and 1.99 vol%, 1.24 and 5.41 vol% for the MWCNT/PCL and MWCNT/iPP nanocomposites, respectively. The electrical and rheological percolation may happen in the samples with a sparse MWCNT network, while EMW SE percolation may require a dense MWCNT network in the samples.

Ultrasonic dispersion of multi-walled carbon nanotubes aided by pyrene-polyether dispersants and Al2O3 particles

Ultrasonic dispersion of multi-walled carbon nanotubes aided by pyrene-polyether dispersants and Al2O3 particles

Additive Manufacturing of Electrically Conductive Nanocomposites Filled with Carbon Nanotubes

Herein, two photopolymers containing multi‐walled carbon nanotubes (MWCNTs) are newly developed to 3D print electrically conductive structures via near‐visible light (405 nm) stereolithography (SL) process. A free‐radical resin and a hybrid cationic/free‐radical photopolymer are used as a matrix and loaded with MWCNTs. A solution mixing method is selected to obtain an optimal MWCNTs dispersion. Rheological and photo‐calorimetric analyses are performed by varying filler concentrations (0.25%, 0.50%, 0.75 wt%) as well as electrical properties of the cured nanocomposites are measured. Rheological characterization indicates the free‐radical resin loaded with the 0.25 wt% of MWCNTs as the most suitable material for the 3D printing of electro‐active systems because it guarantees a rapid and homogenous resin recoating in the vat during the printing of two different layers due to its fluidity. The optimal printing parameters for this photocurable MWCNTs‐loaded resin are found through photosensitivity and photo‐calorimetric analyses. Electrically conductive structures with a conductivity value of 0.0006 S cm−1 are successfully printed, showing the immense potential of these conductive polymeric materials in replacing other standard silicon‐based materials manufactured by conventional 2D lithographic processes for the development of electronic devices and microelectromechanical systems (MEMS).

A comparative study of GNPs and MWCNTs additives on dispersion behavior and strength characteristics of the adhesively bonded joints

In this research, the effects of graphene nanoplatelets (GNPs) and multi-walled carbon nanotubes (MWCNTs) inclusion at various weight fractions (0.25, 0.5, 0.75, and 1 wt%) on the dispersion behavior and strength characteristics of adhesively bonded joints were experimentally investigated and compared. For uniform dispersion of GNPs and MWCNTs across adhesive, an extensive solution mixing technique was carefully carried out. Two types of lap joints, that is, single lap joint (SLJ) and double strap joint (DSJ) were prepared using the neat and modified adhesive. The joints were fabricated using Al 5083 as adherends. A comparison of the strength properties was made after tensile testing of the lap joints. A substantial increase in the strength properties was observed with the added GNPs and MWCNTs. However, the strength response depicted by MWCNTs was superior to GNPs. A maximum improvement of 60% and 31% in lap shear strength was observed for SLJ and DSJ, respectively. This improved response was depicted at 1 wt% of MWCNTs addition in the adhesive. Fourier-transform infrared spectroscopy (FTIR) and ultraviolet–visible spectroscopy (UV–Vis-Nir) were utilized for chemical and dispersion analysis. Digital and scanning electron microscopy techniques were utilized in close examination of the fracture surfaces at high magnifications. Finally, a comprehensive discussion on the difference in strengthening mechanism between the two nanofillers was critically discussed.

Terahertz Absorption Characteristics of Multiwalled Carbon Nanotube Aqueous Dispersion Measured by Microfluidic Technique

Multiwalled carbon nanotubes (MWCNTs) have excellent electronic, mechanical, and structural characteristics; however, their poor dispersion structure and large aggregates severely inhibit their function. A stable MWCNT dispersion in an aqueous solvent has been realized via ultrasonic dispersion and surfactant modification, providing a reference for improving MWCNT dispersion in various materials and solvents. In this study, a cyclic olefin copolymer with high transmittance to terahertz (THz) waves is used to prepare microfluidic chips. Then, the microfluidic and THz technologies are combined to study the THz absorption characteristics of MWCNT aqueous dispersion under different electric field (EF) intensities, magnetic field (MF) intensities, and MF action time. The results show that the THz spectral intensity of MWCNT aqueous dispersion decreases and the absorption coefficient increases with the increase of EF intensity, MF intensity, and MF action time. This phenomenon is explained from a microscopic perspective. The combination of microfluidic and THz technologies provides technical support for studying the characteristics of MWCNT aqueous dispersion and lays a foundation for elucidating the molecular microstructure of MWCNT aqueous dispersion.

Effect of multi‐walled carbon nanotube localization on toughening mechanism and electrical properties of compatibilized PP/EOC immiscible blend

AbstractToughness modification of polypropylene (PP), a widely used polymer in industry, is an important factor in overcoming mechanical limitations and extending its scope of application. In the present work, we utilized a combination of nanoparticle and elastomer techniques to enhance the toughness of PP. Accordingly, the nanocomposite blends, including PP, ethylene octene copolymer (EOC), and multi‐walled carbon nanotubes (MWCNTs), were prepared through three different feeding methods (direct, sequential, and masterbatch). The results demonstrated that the different feeding methods significantly affect the localization and dispersion degree of the MWCNTs, and hence, toughness modification. The results also showed that the sequential is the most effective method to prepare the nanocomposites with the reinforced fracture toughness so that the addition of 2 phr MWCNTs to the PP/EOC blend leads to a high impact strength (=351.61 J/m). Because in this feeding method, most of the highly dispersed MWCNTs can be selectively located in the EOC particles as well as the interface, which can not only intensify the interfacial interactions between the two phases but also help the stress transfer and superposition of stress fields. Moreover, it was shown that in the sequential method, the MWCNTs could facilitate the creation of electrically conductive pathways as a result of nanoparticle bridging and the formation of an interconnected percolating network, therefore increasing the electrical properties.