Carbon Black Polymer Composites Research Articles

Porous carbon black-polymer composites for volatile organic compound adsorption and efficient microwave-assisted desorption

Adsorbents with high surface area, thermal stability and microwave absorption ability are highly desired for cyclic adsorption and microwave regeneration processes. However, most polymeric adsorbents are transparent to microwaves. Herein, porous hyper-crosslinked polymers (HCP) of (4,4′-bis((chloromethyl)-1,1′-biphenyl-benzyl chloride)) with different carbon black (CB) contents were synthesized via the Friedel-Crafts reaction. CB was selected as the filler due to its low cost and high dielectric loss and was embedded inside the polymer structure during polymerization. CB-containing composites showed enhanced thermal stability at elevated temperatures, and more than a 90-times increase in the dielectric loss factor, which is favorable for microwave regeneration. Nitrogen physisorption analysis by the Bruner-Emmett-Teller isotherms demonstrated that CB presence in the polymer structure nonlinearly decreases the surface area and total pore volume (by 38% and 26%, respectively at the highest CB load). Based on the characterization testing, 4 wt% of CB was found to be an optimum filler content, having the highest MW absorption and minimal effect on the adsorbent porosity. HCP with 4 wt% CB allowed a substantial increase in the desorption temperature and yielded more than a 450% enhancement in the desorption efficiency compared to HCP without CB.

Liquid metal based electrical driven shape memory polymers

Electrical driven shape memory polymers (SMPs) have received lots of attention due to their unique electrical-deformation behaviors. Traditional electrical active SMPs are usually based on rigid metals or carbon (such as carbon black and carbon nanotube) polymer composites, which suffer from low flexibility, poor deformation ability and high applying voltages. Here, we reported a liquid metal (LM)-based electroactive SMP by introducing liquid metal into the typical shape memory polymer, polycaprolactone (PCL). The resulted LM-SMP film was highly flexible and showed strain dependent electrical conductivities. With 30% volume LM loading, LM-SMP-30% exhibited a unique transition from insulator to conductor upon stretching. LM-SMP exhibited excellent shape memory performance with a shape fixation rate of 95% and a shape recovery rate of 99%. More importantly, LM-SMP could be electrically driven at low voltages (~2 V) ascribe to phenomenal conductivity of liquid metal. In addition, a reversible actuator was fabricated based on LM-SMP bilayer films, which showed reversible actuation under low external voltages. This work showed that the combination of SMP and LM could be a promising technique for electrical driven systems including soft robotics and advanced electronics.

Flexible Porous Carbon Black-Polymer Composites with a High Gauge Factor

Flexible Porous Carbon Black-Polymer Composites with a High Gauge Factor

Application of 3D printed polymer composite as capacitive sensor

PurposeThe purpose of this study is to demonstrate the usage of three-dimensionally (3D) printed polylactic acid (PLA)-carbon black (CB) conductive polymer composite in the measurement of the void fraction and liquid level.Design/methodology/approachPLA-CB conductive polymer composite is 3D printed through fused deposition modelling (FDM) technique and used as a capacitive sensor for void fraction measurement and liquid level sensing. The sensitivity of 3D printed ring and concave type capacitive sensors are compared for void fraction measurement. The effect of electrode length, thickness and pipe dimension on the capacitance achievable for the particular void fraction is studied. Concept of fringing capacitance is used for the sensing of liquid level.FindingsCompared to the concave design comprising four electrodes, the ring-type capacitive sensor produced better results in void fraction measurement. Increase in pipe diameter and electrode length results in the enhancement of capacitance arising from specific void fraction. For a 100 mm diameter pipe, the capacitance of the 150 mm-long concave electrode (0.4 mm thick) increased from 9.98 to 67.77 pF as the void fraction decreased from 100% to 0%. Development of the fringing capacitance in 3D printed PLA-CB composite helps in the measurement of liquid level. Both parallel finger topology and interdigital electrode configuration are able to sense the liquid level.Originality/valueAbility of the 3D printed conductive PLA-CB composite to act as a capacitive sensor is experimentally analysed. Performance of different electrode configuration is tested for both void fraction measurement and liquid level sensing. Results of experimentation prove that FDM printed PLA-CB composite is suitable for the void fraction and liquid level measurement.

Direct cell imprint lithography in superconductive carbon black polymer composites: process optimization, characterization and in vitro toxicity analysis

Cell imprint lithography (CIL) or cell replication plays a vital role in fields like biomimetic smart culture substrates, bone tissue engineering, cell guiding, cell adhesion, tissue engineering, cell microenvironments, tissue microenvironments, cell research, drug delivery, diagnostics, therapeutics and many other applications. Herein we report a new formulation of superconductive carbon black photopolymer composite and its characterization towards a CIL process technique. In this article, we demonstrated an approach of using a carbon nanoparticle-polymer composite (CPC) for patterning cells. It is observed that a 0.3 wt % load of carbon nanoparticles (CNPs) in a carbon polymer mixture (CPM) was optimal for cell-imprint replica fabrication. The electrical resistance of the 3-CPC (0.3 wt %) was reduced by 68% when compared to N-CPC (0 wt %). This method successfully replicated the single cell with sub-organelle scale. The shape of microvesicles, grooves, pores, blebs or microvilli on the cellular surface was patterned clearly. This technique delivers a free-standing cell feature substrate. In vitro evaluation of the polymer demonstrated it as an ideal candidate for biomimetic biomaterial applications. This approach also finds its application in study based on morphology, especially for drug delivery applications and for investigations based on molecular pathways.

Designing formulation variables of extrusion-based manufacturing of carbon black conductive polymer composites for piezoresistive sensing

Highly sensitive conductive polymer composites for piezoresistive sensing are developed by a design of the formulation variables of extrusion-based manufacturing (filler type/amount, polymer amount) and annealing (a), considering thermoplastic polyurethane (TPU) and/or olefin block copolymer (OBC) as polymer matrix and carbon black (CB) as conductive filler. With ternary composites - based on a CB type with stronger filler-matrix interactions and an appropriate OBC/TPU blend mass ratio (40/60 with CB amount of 5–10 m%; 50/50 with CB amount of 10 m%), the challenging region of both high sensitivity and static strain (maximal gauge factors (GFmax) > 50 and εmax > 100%) can be realized: GFmax > 104 and εmax = 20–240%. OBC binary composites with a high CB2 amount (e.g. 15 m%) are however needed for ultrahigh static strains (εmax > 600%). Well-designed ternary composites (e.g. OBC40-CB/TPU60-7-a and OBC30-CB/TPU70-7-a) possess a large dynamic resistance change, negligible hysteresis and high stability and display strain sensor application potential. Highly CB2 loaded binary (≥12 m%) and ternary composites (10 m%) exhibit a more obvious strain-dependent dynamic hysteretic behavior, as they switch from a dual peak to single peak pattern toward the sensing strain limit, which is interesting for self-diagnose.

Dynamic behavior and damping characteristics of carbon black polymer composites at high strain rates

AbstractThe dynamic stress–strain behavior and the damping characteristics of carbon black (CB)/polymer composites at high strain rates are measured using the split Hopkinson pressure bar. These characteristics are determined for polyurethane impregnated with 20% CB nanoparticles and compared with those of pristine polyurethane at strain rates ranging between 2,400 and 7,000 s−1. The obtained results indicate that the CB/polymer composites exhibit highly hysteretic stress–strain characteristics and have high storage modulus as well as high loss factor as compared to pristine polyurethane polymers. With such characteristics, the CB/polymer composites are observed to dissipate energy much higher than that dissipated by pristine polymers.

The effect of MWCNTs on the electrical properties of a stretchable carbon composite electrode

Abstract Stretchable electrodes are of great interest with increasing demands for flexible electronic devices. Carbon black polymer composites do not show increasing resistivity during stretching, but resistivity decreases in a certain range. However, the electrical conductivity of carbon black is insufficient for electrodes. Multi-wall carbon nanotubes (MWCNTs) are carbon-based nanostructures that impart good electrical conductivity and flexibility with a high aspect ratio. CNTs may help to improve the electrical conductivity of carbon black. In this study, MWCNTs were added to a carbon black electrode with a simple process and then investigated. Adding MWCNTs introduced two benefits to the electrical properties of carbon black composites for use as a stretchable electrode. The addition of MWCNTs reduced the electrical resistivity of the carbon electrode as it connected non-contacting carbon black particles to enhance the effective conductive network. Also, MWCNTs minimized the increase in the resistance of the carbon electrode during stretching because they bridged separate carbon black aggregates and aligned along the stretching direction to enhance conductive path and inhibit crack growth. Additionally, the electrical resistance of MWCNTs in the carbon black electrode was maintained after repetitive stretching. A stretchable electrode showed stable electrical behavior under a strain of 25% after repetitive stretching.

The percolation staircase model and its manifestation in composite materials

We studied the tunneling percolation conductivity dependence on the site or bond occupation probability in the square lattice. The model predicts that in both, lattice and continuum systems in which there is a hierarchy of the local conductances, the dependence of the global conductivity on the site or volume occupation probability will yield a conductivity staircase. In particular we evaluate the implications of the staircase on the critical behavior of the conductivity. We then show experimental evidence for the predicted percolation-tunneling staircase in a Ag-Al2O3 granular metal system and in a carbon black-polymer composite. Following that, we propose that for carbon nanotube (CNT) polymer composites the data in the literature give ample support to a percolation-dispersion staircase behavior. The implication of the present findings on the percolation-hopping problem in composite materials is also discussed.

Use of Gas-Sensor Array Technology in Lung Cancer Diagnosis

Gas-sensor array technology, which has been much utilized in the field of food technology by the name of 'electronic nose' is drawing attention in diagnosing lung cancer based on the analysis of the exhaled human breath. Much understanding has been accomplished about the composition of the volatile organic compounds (VOCs) of the human exhaled breath, in spite of some variations depending on research groups due mainly to lack of the standardization of the sensing procedures. Since VOCs may be produced during the process of cellular metabolism, difference in the cellular metabolism between healthy cells and lung cancer cells are expected to be reflected on the composition variation of the exhaled VOCs. Several studies have attempted to apply the gas-sensor array technology to lung cancer analysis using many different types of sensors including metal oxide, carbon black-polymer composite, surface acoustic wave, and gold nanoparticles. In this mini-review VOC as biomarkers, sensor array technology and application of the array technology for the diagnosis of cancer disease have been described.

Electromagnetic Interference Shielding Efficiency in the Range 8.2-12.4 GHz of Polymer Composites with Dispersed Carbon Nanoparticles

In the present work, electromagnetic interference shielding properties of polymer composites with dispersed cup-stacked carbon nanotubes, graphite nanoparticles and carbon black were investigated. The polymer composites with carbon nanoparticles content from 1 to 5 w% were successfully prepared by the coagulation method, and composite sheets with thickness from 0.25 to 0.77 mm were formed by the hot press technique. The electromagnetic interference shielding efficiency measured in the frequency range of 8.2~12.4 GHz (X-band) of cup-stacked carbon nanotubes/polymer composite was considerably higher than that of carbon black and graphite nanoparticles polymer composites at the same contents of carbon nanoparticles, and contribution of absorption to the shielding efficiency was found to be higher than that of reflection.

DC electrical conductivity of carbon black polymer composites at low temperatures

The understanding of the charge transport mechanism of the conducting polymers and their composites is important for the successful fabrication of semiconductor devices. In this work, the DC electrical conductivity of carbon black particles in a polystyrene matrix, in the temperature range of 80 to 250 K is examined, for concentrations below the critical percolation concentration. We show that three-dimensional variable range hopping is observed, that is, the temperature behavior of the DC conductivity can be expressed by σ = σ 0 exp − T 0 T 1 4 . From the hopping parameter we obtained the mean hopping distance, the density of active centers and the energy associated with it.

A modified model of electrical conduction for carbon black–polymer composites

AbstractA modified model of electrical conduction for carbon black‐polymer composites is proposed based on the general effective media theory and the number of carbon black particles per aggregate to describe their nonlinear conductive behavior. In order to consider the interactions between carbon black particles, a simple self‐consistent approach is used to improve the model. Expressions of electrical conductivity and percolation threshold are derived from the modified model. The predicted results of electrical conductivity and percolation threshold are in good agreement with experimental data reported in previous literature. Moreover, the dependences of electrical conductivity and percolation threshold on the number of carbon black particles per aggregate are discussed. Copyright © 2010 Society of Chemical Industry

Portable electronic nose system with chemiresistor sensors to detect and distinguish chemical warfare agents

Electronic nose has been studied as a means to realize artificial olfaction. Currently there are still only relatively large electronic nose “instruments”, since the signal manipulation and classification are still done by a personal computer or a laptop. A portable electronic nose system based on hand-held machine has been developed by using the vapor detection array made of carbon black-polymer composites and the sensor circuit. In an effort to make a portable electronic nose, we used thin-film chemical sensors based on carbon black polymer nanocomposite to reliably detect chemical warfare agents. The use of FPGA to replace the PC has also been studied. The eNose system was exposed to dimethyl-methylphosphonate (DMMP) and DCMin part per million (ppm) concentration levels. DMMP and DCM were considered as stimulants of nerve agent-sarin, incapacitating agent-BZ gases, respectively.

Electron tunneling in conductor-insulator composites with spherical fillers

We report on our Monte Carlo calculations of the conductivity of monosized and conducting spherical particles dispersed in a homogeneous matrix, with interparticle transport mechanism given by electron tunneling. We show that our numerical results can be reproduced by a simple formula based on a critical path analysis and which gives also a practical way to estimate the characteristic tunneling length ξ in real composites. We find that ξ is about 1 nm for several low structure carbon black polymer composites, in agreement with the expected order of magnitude.

Gas sensor measurement system capable of sampling volatile organic compounds (VOCs) in wide concentration range

A gas sensor measurement system has been developed by using a vapor-generating bubbler, analyte-diluted delivery lines and a detection chamber. The bubbler with a perforated disk design permits to pick up analyte vapor with fixed efficiency under a carrier flow rate of 0.5–100 sccm. The pickup efficiency was modulated logarithmically by varying the bubbler temperature. The practically controllable range in acetone flux was nearly three orders of magnitude through the variation of the carrier flow rate, and an order of magnitude by the use of the bubble temperature, independently. The generated vapor was diluted efficiently through a cascading two-step process which leads to homogeneous mixing up to the flow ratio of dilution:carrier = 500:0.25, and then delivered into a small-gapped planar detection chamber operated at room temperature. The newly-designed planar chamber induces fast equilibrium and high local concentration on a sensor surface, thus resulting in a short detection time and a higher response magnitude. From measuring chemoresistive responses of carbon black-polymer composites upon exposure to acetone analyte, the measurement system was confirmed to be reliably applicable to a wide concentration range of from 3.7 ppm to 10.7%.

Nanoparticle induced network self-assembly in polymer–carbon black composites

A novel percolation phenomenon with inorganic nanoparticle loading in polyamide 6-carbon based nanoparticle hybrids was identified. Percolation threshold substantially shifts to lower carbon black (CB) volume fractions in the presence of optimum concentration of chemically modified montmorillonite (organoclay) while the effective organoclay concentration can be optimized to lower the slope of percolation curve maintaining electrical conductivity within static dissipative 10−6–10−9Scm−1 range. Organoclay/CB ‘nano-unit’ morphology was found in polyamide 6 ternary hybrids. It is composed of stacked organo-montmorillonite platelets that deform to wrap partially around one or two primary CB aggregates. This elementary nano-unit structure induces CB network self-assembly within polyamide 6 matrices. The structure was found to be prevalent throughout the polymer matrix. This morphology remains robust under wide range of thermal-deformation histories due to the strong preferred organoclay/polyamide 6/CB interactions that partially blocks the electron conduction and hopping mechanisms with clay ‘walls’ thereby reducing the slope of the percolation curve. Organoclay can be used as a dispersion control agent in these polymer–carbon systems to induce self-assembly of CB network at low CB content, simultaneously, partial blocking the electron hopping pathways to level the slope of percolation curves. High order exfoliation and nano-scale dispersion of organoclay is essential to induce this advanced percolation phenomenon.

Miniaturized Electronic Nose System Based on Personal Digital Assistant

A small electronic nose (E-Nose) system has been developed using an 8-channel vapor detection array and personal digital assistant (PDA). The sensor array chip, integrated on a single microheater-embedded polyimide substrate, was made of carbon black-polymer composites with different kinds of polymers and plasticizers. We have successfully classified various volatile organic compounds such as methanol, ethanol, i-propanol, benzene, toluene, n-hexane, n-heptane, and c-hexane with the aid of the sensor array chip, and have evaluated the resolution factors among them, quantitatively. To achieve a PDA-based E-Nose system, we have also elaborated small sensor-interrogating circuits, simple vapor delivery components, and data acquisition and processing programs. As preliminary results show, the miniaturized E-Nose system has demonstrated the identification of essential oils extracted from mint, lavender, and eucalyptus plants.

Electrical response of Poly(styrene)/carbon black conductive polymer composites (CPC) to methanol, toluene, chloroform and styrene vapors as a function of filler nature and matrix tacticity

We have studied the sensing properties of several conductive polymer composites (CPC) to saturated solvent vapors (methanol, toluene, chloroform and styrene) as a function of carbon black (CB) structure and poly(styrene) PS crystal Unity. It appears that the combination of these two previous parameters allows obtaining very different electrical signature for the four vapors studied, confirming the importance of the carbon black conductive pathways morphologies structuring during the process. This study shows that selectivity of the CPC toward the vapors can be obtained not only by changing the matrix chemical nature but also by tailoring the morphology of the CB network.

Detection and Classification of Volatile Organic Amines and Carboxylic Acids Using Arrays of Carbon Black-Dendrimer Composite Vapor Detectors

Carbon black-insulator composite chemiresistive vapor detectors have been prepared using dendrimers as the polymeric constituent of the composite. Amino-terminated dendrimer-carbon black composites exhibited an enhancement in detection sensitivity of ∼103 for volatile carboxylic acids as compared to nondendrimeric insulating polymer-carbon black composites. Similarly, protonated carboxylato-terminated and protonated amino-terminated dendrimer-carbon black composites showed an ∼103−104 increase in sensitivity for detection of volatile amines relative to the response of nondendrimeric insulating polymer-carbon black composites. The protonated amino-terminated dendrimer carbon black composite detectors exhibited a signal-to-noise ratio (S/N) of 22.4 ± 0.9 upon exposure to 2.7 ppb of butylamine in air, whereas poly(ethylene oxide)-carbon black composites exhibited a S/N of 3.5 ± 1.2 at 54 ppm of butylamine. The protonated amino-terminated dendrimer-carbon black detectors additionally exhibited relatively small responses to water vapor. Compositional diversity in an array of protonated amino-terminated dendrimeric vapor detectors was obtained by varying the type and generation of the dendrimer, and the type and concentration of the acid dopant. Fifteen analytes chosen from primary amines, branched amines, anilines, and non-amine organic analyte vapors were all robustly discriminated from each other by their different response patterns on the dendrimer-containing detector array. The signals produced by these 15 analytes additionally clustered into groups based on the chemical class of the analyte.