Distribution Of Conductive Particles Research Articles

Characterization of conductive particle dispersion in textile coatings through Joule’s effect monitoring analysis

Achieving proper dispersion of pigments, dyes, or other additives, such as microcapsules or nanoparticles, within printing pastes or textile coatings is crucial for obtaining a homogeneous result. In certain specialized applications, such as coloration technology, it is possible to use colorimetry tools, visual examination, and even artificial vision to identify defects. However, none of these techniques comprehensively map the specific additive distribution. This paper proposes a novel approach: monitoring the distribution of conductive particles (graphene nanoplatelets, referred to as GNPs) within an acrylic coating paste using the Joule’s effect. Four different dispersion systems (ultrasound mixer, blender, toroidal agitation, and three-roll mill) are employed. Thermographic images provide an accurate view of how conductive particles are distributed. This complements data from numerical values, such as the maximum and average temperatures recorded for each sample. In certain cases, relying solely on numerical values can be inadequate or insufficient, hence the novelty of this article emphasizing the significance of using the Joule’s effect to assess the distribution of conductive particles. Concerning the mixing systems, optimal dispersion of GNPs in distilled water is most effectively achieved using an ultrasound mixer, with enhanced uniformity as dispersion time increases. For mixing the components of the coating paste, the toroidal agitation method yields the best result. Employing the three-roll mill is discouraged for this application due to its propensity to induce phase separation.

Nanoparticle orientation distribution analysis and design for polymeric piezoresistive sensors

Piezoresistive sensors, with polymer matrices and conductive nanoparticles, are a relatively new addition to the sensor class, with the potential to transform such fields as wearable sensors and the internet of things. The unusual inverse piezoresistive behavior of the sensors has been modeled using quantum tunneling and percolation theory. However, the impact of the distribution of conductive particles in the matrix, and specifically their relative orientation, has not been well studied. The initial and deformed distribution of orientations greatly influences the sensor behavior, since the quantum tunneling model is highly sensitive to the polymer gaps between nanoparticles; the evolution of these gaps under deformation is strongly dependent upon the relative orientation of neighboring particles, and determines electron transport properties, and overall sensor response. In this paper a simple analytical model for isotropic orientation distribution and subsequent Poisson-based gap evolution is compared with a more sophisticated finite element and random resistor network analysis. The new numerical model was able to explain previously unexplained physical behavior and is used to design sensors with specific desired characteristics. The appropriateness of the previously assumed percolation behavior is also examined via the model and generalized effective medium theory.

Controllable distribution of conductive particles in polymer blends via a bilayer structure design: a strategy to fabricate shape-memory composites with tunable electro-responsive properties

Bilayer composites enable tunable electro-responsive shape-memory performances via the controllable distribution of MWCNTs.

Geometric Optimization of Li-O2 Battery Cathodes with Pore Structure By Meso-Scale Modeling and Simulation Pursuing Practical Systems

Recent demands for post Li-ion batteries attracted enormous attentions to Li-air battery that is theoretically capable over 3000 Wh/kg specific energy [1].Since first introduction of the Li-air battery by Abraham and Jiang in 1996 [2], various experimental studies have been conducted to explore detailed physical and chemical properties as well as practical feasibilities of this energy storage system [3]. The most dominant reaction mechanism so far known is that lithium ion react with oxygen producing Li2O2 in a non-aqueous electrolyte and carbon composite cathode [3].The reaction product, Li2O2, is an insulator with a wide band gap that limits capacity of the cell when it deposits and passivates all the active surfaces with certain thickness, about 5 - 10 nm [4,5]. Couples of numerical models to assist in predicting the performance of the cell have also been developed by modifying the models developed for Li-ion batteries. However, detailed geometrical optimization of cathode components composed of an electrolyte, carbon particles and pores has not been reported. Among the Li-O2battery research community, it has been the norm that reporting specific capacity versus only carbon weight but for practical and precise assessment, all the components comprising cathode including electrolytes should be considered as they also add mass to total cathode weight. Consequently, the optimization of the ratio of the components is absolutely necessary for practical system design. Here, we modeled and simulated the Li-O2 cell with an electrolyte and with an electrolyte and pores. Percolation limit for electric conduction was introduced to define minimum volume occupied by carbon particles. Dynamic electrodeposition of reaction products with the surface passivation effect that expresses exponentially increasing electric resistance as the film growing was introduced by using the Comsol multi-physics electrodeposition module. Random distribution of conductive particles was realized by using the Bruggeman equation for charge transport thorough a media. The simulated results were verified by experimental results. Li-O2 cells with the cathode comprising of Printex carbon as the conductive media and PEO (polyethylene oxide) containing LiTFSI (lithium bis(trifluoromethanesulfonyl) imide) as the electrolyte were fabricated with various compositions and their charge discharge properties were characterized. Results from both simulation and experiments showed good agreement in trends for flooded type cells and suggests optimized the ratio of components. [1]Bruce, P. G. et al. Li-O2 and Li-S batteries with high energy storage. Nat. Mater. 11, 19-29 (2012) [2]Abraham, K. M. and Jiang Z. A polymer electrolyte-based rechargeable lithium/oxygen battery. J. Electrochem. Soc. 143, 1-5 (1996) [3]Amin, K. et al. Aprotic and aqueous Li-O2 batteries Chem. Rev., Article ASAP http://pubs.acs.org/doi/abs/10.1021/cr400573b (2014) [4]Luntz, A. C. Tunneling and polaron charge transport through Li2O2 in Li-O2 batteries. Phys. Chem. Lett. 4, 3494-3499 (2013) [5]Viswanathan, V. Electric conductivity in Li2O2 and its role in determining capacity limitations in non-aqueous Li-O2 batteries. J. Chem. Phys. 153, 214704 (2011)

Electrical properties of polypropylene-based composites controlled by multilayered distribution of conductive particles.

Materials consisting of alternating layers of pure polypropylene (PP) and carbon black filled polypropylene (PPCB) were fabricated in this work. The electrical behaviors of the multilayered composites were investigated from two directions: (1) Parallel to interfaces. The confined layer space allowed for a more compact connection between CB particles, while the conductive pathways tended to be broken up with increasing number of layers leading to a distinct enhancement of the electrical resistivity due to the separation of insulated PP layers. (2) Vertical to interfaces. The alternating assemblies of insulated and conductive layers like a parallel-plate capacitor made the electrical conductivity become frequency dependent. Following the layer multiplication process, the dielectric permittivity was significantly enhanced due to the accumulation of electrical charges at interfaces. Thus, as a microwave was incident on the dielectric medium, the interfacial polarization made the main contribution to inherent dissipation of microwave energy, so that the absorbing peak became strengthened when the material had more layers. Furthermore, the layer interfaces in the multilayered system were also effective to inhibit the propagation of cracks in the stretching process, leading to a larger elongation at the break than that of the PP/CB conventional system, which provided a potential route to fabricate electrical materials with optimal mechanical properties.

Correction: Dielectric hysteresis behaviors of polyvinylidene fluoride-based multilayer dielectrics controlled by confined distribution of conductive particles

Correction for ‘Dielectric hysteresis behaviors of polyvinylidene fluoride-based multilayer dielectrics controlled by confined distribution of conductive particles’ by Jiaming Zhu et al., RSC Adv., 2015, 5, 65927–65931.

Dielectric hysteresis behaviors of polyvinylidene fluoride-based multilayer dielectrics controlled by confined distribution of conductive particles

PVDF-based multilayer dielectrics were fabricated through layer-multiplying extrusion and the dielectric hysteresis behaviors were successfully tailored by confined distribution of conductive particles.

Confined distribution of conductive particles in polyvinylidene fluoride-based multilayered dielectrics: Toward high permittivity and breakdown strength

Polyvinylidene fluoride (PVDF)-based multilayered dielectrics containing alternating layers of confined carbon black (CB) were fabricated using a layer-multiplying extrusion. For a given film thickness, a large enhancement of dielectric permittivity occurred following the increase of CB containing layers. When the number of total layers reached 256, the permittivity at 103Hz became 3 times higher than that predicted by the series model. A frequency dependence in the dielectric loss curves caused by the layer multiplication process was also observed. The differences in capacitance and conductivity between neat PVDF and CB containing layers resulted in charge accumulation at their interfaces, leading to an increase in the permittivity and the dielectric loss peak intensity. Furthermore, the presence of PVDF between the CB containing layers distinctly improved the breakdown strength of the multilayered films by at least two orders of magnitude higher than that of the PVDF/CB conventional composite at a similar CB loading or conductivity level. The present approach for the preparation of high-k dielectrics with high breakdown strength would significantly broaden the choices of dielectric materials for pulse powered, high field electronics and a new generation of clean energy applications.

Microwave preheating of anisotropic conductive adhesive films for high-speed flip chip on flex bonding

Anisotropic conductive adhesive film (ACF) can be preheated by microwave (MW) radiation in order to reduce the bonding time for flip-chip technology. Due to sluggish and nonuniform curing kinetics at the beginning of the curing reaction, thermal curing of epoxy is more time consuming. Therefore, MW radiation may be more effective, due to its uniform heating rate during the cycle. In this paper, MW preheating (for 1–4 sec) of ACF prior to final bonding has been applied to determine the electrical and mechanical performance of the bond. Powers of 80 and 240 W MW were used to study the effect of the MW preheating. A final bonding time of 6–7 sec can be used for flip chip on flex bonding instead of 10–15 sec (standard time for flip chip bonding) for MW preheating time and power used in this study. The contact resistance (as low as 0.01) is low in these samples, whereas the standard resistance is 0.017 ohm (bonded at 180°C for 10 sec without prior MW preheating). The shear forces at breakage were satisfactory (0.167–0.183 KN) for the samples bonded for 6–7 sec with MW preheating. This is very close and even higher than the standard sample (0.173 KN). For MW preheating power of 80 W and sweeping time of 2 sec, final bonding at 6 sec can also be used because of its low contact resistance (0.019 ohm). Scanning electron microscope (SEM) investigation of microjoints and fracture surface shows uneven distribution of conductive particles and thick bond lines in samples bonded for 5 sec (with MW preheating). Samples treated with MW radiation (80 W and 2–3 sec time) serve as evidence that well-distributed particles along with thin bond lines cause low contact resistance and high joint strength.

Theoretical Analysis of RF Performance of Anisotropic Conductive Adhesive Flip-Chip Joints

The RF performance of a single flip-chip joint using anisotropic conductive adhesive (ACA) was modeled using three-dimensional finite difference in time domain (FDTD) methodology. The effects of the number, the distribution of ACA conductive particles, as well as the ACA resin, on RF transition of the joint were studied. The results show that the number and the distribution of conductive particles as well as the adhesive resin have limited influence on the RF performance of an ACA flip-chip joint. Based on the FDTD simulation results, an equivalent circuit model of a single ACA flip-chip joint was also proposed.

Heterogeneous distribution of conductive particles in polymer blends studied by electron microscopy.

The distribution state of carbon black (CB) was observed in polymer blends by scanning (SEM) and transmission (TEM) electron microscopies. CB distributed unevenly in the polymer blend. There were two types of distribution. In the first type, CB particles were predominantly distributed in one phase of the blend matrix. In the second type, the fillers concentrate at the interface of two polymers. This heterogeneous distribution of fillers in a polymer blend matrix was mainly due to the difference in affinity of CB particles to each component of the polymer blend. In high density polyethylene/polypropylene blend, CB particles were mainly located in the polyethylene phase. When oxidated CB particles were used, however, they were concentrated at the interface of the two polymer phases.