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Conductive Polymer Composites (conductive + polymer_composite)

Distribution by Scientific Domains

Polymers and Materials Science	90%

Selected Abstracts

Study of prelocalized graphite/styrene acrylonitrile conducting composites for device applications

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2006
V. K. Sachdev
Abstract Conductive polymer composites were prepared by compression molding of prelocalized graphite on to styrene acrylonitrile (SAN) particles. The electrical conductivity is found to be strongly dependent on the graphite content. Three different series were prepared for different processing and material parameters. A low percolation threshold has been noticed when only 1 wt% of graphite is incorporated. Resistivity as low as ,14 , cm has been achieved in a composite with SAN resin particles of 180,212 µm size and graphite 10,20 µm at 90 °C, 105 MPa and 15 min. An electrically conducting network of graphite channels has been observed using scanning electron microscopy. V,I characteristic reveals that at a lower percentage of graphite the increase in current with increase in electric field is due to the hopping/tunneling of electrons, while for higher percentages of graphite ohmic behavior similar to metals has been observed. The data has been analyzed using percolation model. The value of the exponent t that determines the increase in electrical conductivity above the percolation threshold is found to be close to the values given in the literature. The theoretically calculated values of conductivity are found to be in satisfactory agreement with the experimental ones. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Partially miscible poly(lactic acid)- blend -poly(propylene carbonate) filled with carbon black as conductive polymer composite

POLYMER INTERNATIONAL, Issue 9 2008
Wang Ning
Abstract BACKGROUND: Conductive polymer composites (CPCs) can be obtained by filling polymer matrices with electrically conductive particles, and have a wide variety of potential applications. In the work reported, the biodegradable polymer poly(lactic acid) (PLA) as a partially miscible blend with poly(propylene carbonate) (PPC) was used as a polymer matrix. Carbon black (CB) was used as the conducting filler. RESULTS: Fourier transform infrared spectroscopy revealed interactions between matrix and CB filler; this interaction was stronger in PPC- blend -CB than in PLA- blend -CB composites. A rheology study showed that low-viscosity PPC could improve the fluidity of the CPCs, but decrease that of CB. With increasing CB content, the enforcement effect, storage modulus and glass transition temperature increased, but the elongation at break decreased. CPCs exhibited the lowest electrical percolation thresholds of 1.39 vol.% CB when the content of PPC in PLA- blend -PPC was 40 wt%. The conductivity of CPCs containing 5.33 vol.% CB and 40 wt% PPC reached 1.57 S cm,1. Scanning electron microscopy revealed that CB exhibits a preference for dispersion in the low-viscosity phase (PPC) of the multiphase matrix. CONCLUSION: In the presence of CB, partially miscible PLA- blend -PPC could form multi-percolation CPCs. Moreover, the combination of PLA and PPC with CB broadens novel application of both renewable polymers and CPCs. Copyright © 2008 Society of Chemical Industry [source]

A Novel Concept for Highly Oriented Carbon Nanotube Composite Tapes or Fibres with High Strength and Electrical Conductivity

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 11 2009
Hua Deng
Abstract A new concept is described for the creation of multifunctional polymer nanocomposite tapes (or fibres) that combines high stiffness and strength with good electrical properties and a low percolation threshold of carbon nanotubes (CNTs). The concept is based on a bicomponent tape (or fibre) construction consisting of a highly oriented polymer core and a conductive polymer composite (CPC) skin based on a polymer with a lower melting temperature than the core, enabling thermal annealing of these skins to improve conductivity through a dynamic percolation process while retaining the properties of the core and hence those of the tape (or fibre). The percolation threshold in the CPC skins of the highly drawn conductive bicomponent tapes could be decreased from 5.3 to 1.1,wt.-% after annealing. [source]

Formation of in situ CB/PET Microfibers in CB/PET/PE Composites by Slit Die Extrusion and Hot Stretching

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 6 2004
Xiang-Bin Xu
Abstract Summary: In this present study, the in situ fabrication of a microfibrillar composite based on poly(ethylene terephthalate) (PET), polyethylene (PE), and carbon black (CB) is attempted. PET and CB were first melt mixed. The CB/PET compound and PE were subsequently melt extruded through a slit die and then hot stretched. The morphological observation of the as-stretched extrudate indicated that well-defined microfibers of CB/PET compound could be generated at appropriate CB contents and a fixed hot stretch ratio. In addition, CB was always selectively located in PET. The microfibrillar CB/PET/PE composite has the potential to be a new electrically conductive polymer composite. Morphology of the carbon black/poly(ethylene terephthalate)/polyethylene (PE) composite after additional mixing in the mixer at the processing temperature of PE. [source]

Partially miscible poly(lactic acid)- blend -poly(propylene carbonate) filled with carbon black as conductive polymer composite

Preparation of High-Performance Conductive Polymer Fibers through Morphological Control of Networks Formed by Nanofillers

ADVANCED FUNCTIONAL MATERIALS, Issue 9 2010
Hua Deng
Abstract A general method is described to prepare high-performance conductive polymer fibers or tapes. In this method, bicomponent tapes/fibers containing two layers of conductive polymer composites (CPCs) filled with multiwall carbon nanotubes (MWNT) or carbon black (CB) based on a lower-melting-temperature polymer and an unfilled polymer core with higher melting temperature are fabricated by a melt-based process. Morphological control of the conductive network formed by nanofillers is realized by solid-state drawing and annealing. Information on the morphological and electrical change of the highly oriented conductive nanofiller network in CPC bicomponent tapes during relaxation, melting, and crystallization of the polymer matrix is reported for the first time. The conductivity of these polypropylene tapes can be as high as 275,S,m,1 with tensile strengths of around 500,MPa. To the best of the authors' knowledge, it is the most conductive, high-strength polymer fiber produced by melt-processing reported in literature, despite the fact that only ,5,wt.% of MWNTs are used in the outer layers of the tape and the overall MWNT content in the bicomponent tape can be much lower (typically ,0.5,wt.%). Their applications could include sensing, smart textiles, electrodes for flexible solar cells, and electromagnetic interference (EMI) shielding. Furthermore, a modeling approach was used to study the relaxation process of highly oriented conductive networks formed by carbon nanofillers. [source]

Effect of solid state grinding on properties of PP/PET blends and their composites with carbon nanotubes

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010
Ozcan Koysuren
Abstract In this study, it was aimed to improve electrical conductivity and mechanical properties of conductive polymer composites, composed of polypropylene (PP), poly(ethylene terephthalate) (PET), and carbon nanotubes (CNT). Grinding, a type of solid state processing technique, was applied to PP/PET and PP/PET/CNT systems to reduce average domain size of blend phases and to improve interfacial adhesion between these phases. Surface energy measurements showed that carbon nanotubes might be selectively localized at PET phase of immiscible blend systems. Grinding technique exhibited improvement in electrical conductivity and mechanical properties of PP/PET/CNT systems at low PET compositions. Ground composites molded below the melting temperature of PET exhibited higher tensile strength and modulus values than those prepared above the melting temperature of PET. According to SEM micrographs, micron-sized domain structures were obtained with ground composite systems in which PET was the minor phase. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source]

Electrical Response to Organic Vapor of Conductive Composites from Amorphous Polymer/Carbon Black Prepared by Polymerization Filling

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 2 2003
Jun Rong Li
Abstract In recent years, conductive polymer composites have found applications as gas sensors because of their sudden change in electric resistance of several orders of magnitude when the materials are exposed to certain solvent vapors. However, the composites having this function reported so far are mostly based on crystalline polymeric matrices, which factually sets a limit to materials selection. The present work prepares polystyrene/carbon black composites through polymerization filling and proves that the amorphous polymer composites can also serve as gas sensing materials. The composites' percolation threshold is much lower than that of the composites produced by dispersive mixing. In addition, high responsivity to some organic vapors coupled with sufficient reproducibility is acquired. The experimental data show that molecular weight and molecular weight distribution of the matrix polymer and conducting filler content exert great influence on the electrical response behavior of the composites. As a result, composites performance can be purposely tailored accordingly. Compared with the approaches of melt-blending and solution-blending, the current technique is characterized by many advantages, such as simplicity, low cost, and easy to be controlled. Effect of different organic solvent vapors on the electric resistance of PS/CB composites (CB content,=,10.35 vol.-%). [source]

Highly Conductive Carbon Nanotube/Polymer Nanocomposites Achievable?

MACROMOLECULAR THEORY AND SIMULATIONS, Issue 3 2009
Xinxin Sun
Abstract Carbon nanotubes (NT) have attracted growing interest in recent years as a conducting filler in the development of conductive polymer composites. However, most of experimental results show that the conductivity of NT/polymer composites is significantly lower than expected. Can NTs be an effective conductive filler for improving the electrical conductivity of polymers? In order to answer this question, a continuum model was constructed by introducing effective tunneling conduction in a non-universal network for the prediction of electrical conductivity of NT/polymer composites. Based on this model, the effect of the microstructure of NT/polymer composites on conductivity was assessed particularly for NT/polyethylene, NT/polyimide, and NT/poly(vinyl alcohol) composites. NT contact resistance and tunneling resistance have significant influences on the conductivity. The effects of the potential barrier of polymer and the tortousity of single-walled NTs on the conductivity were also analyzed. NTs cannot be considered as a valuable conductive filler for the development of highly conductive polymer composites unless the contact and tunneling resistances are reduced significantly. [source]

AC impedance analysis and EMI shielding effectiveness of conductive SBR composites

POLYMER ENGINEERING & SCIENCE, Issue 10 2006
G.T. Mohanraj
Flexible conductive polymer composites were prepared using styrene,butadiene rubber (SBR) as a matrix and conductive carbon black as filler. The filler loading was varied from 10 to 60 phr. The complex AC impedance and electromagnetic interference shielding effectiveness (EMI SE) of the composites were measured at the microwave frequencies of 7.8,12.4 GHz. The effect of variation in filler concentration and measurement frequency on the AC impedance and EMI SE of the composites were investigated. Equivalent circuits describing the conduction behavior of the composites were determined by means of Nyquist plots. The complex electric modulus of the composites was also determined. Increase in the filler loading increased the capacitive nature of the materials. The composites were better defined by a parallel resistor,capacitor circuit in series with a resistor. The EMI SE was found to pass through a maximum with increase in frequency. However, with the increase in filler loading and sample thickness of the material, the EMI SE was found to increase continuously. POLYM. ENG. SCI., 46:1342,1349, 2006. © 2006 Society of Plastics Engineers. [source]