Intrinsically conducting polymers (ICP) and conductive fillers incorporated conductive polymer-based composites (CPC) greatly facilitate the research in electromagnetic interference (EMI) shielding because they not only provide excellent EMI shielding but also have advantages of electromagnetic wave absorption rather than reflection. In this review, the latest developments in ICP and CPC based EMI shielding materials are highlighted. In particular, existing methods for adjusting the morphological structure, electric and magnetic properties of EMI shielding materials are discussed along with the future opportunities and challenges in developing ICP and CPC for EMI shielding applications. 相似文献
An electromagnetic interference (EMI) shielding composite based on ultrahigh molecular weight polyethylene (UHMWPE) loaded with economical graphite-carbon black (CB) hybrid fillers was prepared via a green and facile methodology, i.e., high-speed mechanical mixing combined with hot compression thus avoiding the assistance of the intensive ultrasound dispersion in volatile organic solvents. In this composite, the graphite-CB hybrid fillers were selectively distributed in the interfacial regions of UHMWPE domains resulting a typical segregated structure. Thanks to the specific morphology of segregated conductive networks along with the synergetic effect of large-sized graphite flakes and small-sized CB nanoparticles, a low filler loading of 7.7 vol% (15 wt%) yielded the graphite-CB/UHMWPE composites with a satisfactory electrical conductivity of 33.9 S/m and a superior shielding effectiveness of 40.2 dB, manifesting the comparable value of the pricey large-aspect-ratio carbon nanofillers (e.g., carbon nanotubes and graphene nanosheets) based polymer composites. More interestingly, with the addition of 15 wt% graphite-CB (1/3, W/W) hybrid fillers, the tensile strength and elongation at break of the composite reached 25.3 MPa and 126%, respectively; with a remarkable increase of 58.1% and 2420% over the conventional segregated graphite/UHMWPE composites. The mechanical reinforcement could be attributed to the favor of the small-sized CB particles in the polymer molecular diffusion between UHMWPE domains which in turn provided a stronger interfacial adhesion. This work provides a facile, green and affordable strategy to obtain the polymer composites with high electrical conductivity, efficient EMI shielding, and balanced mechanical performance. 相似文献
Highly conducting polyaniline (PANi)-coated multi-walled carbon nanotubes (MWCNTs) were prepared by in situ polymerization method for electromagnetic interference shielding. The thickness of the PANi coatings was controlled by the oxyfluorination treatment on the multi-walled carbon nanotubes and analyzed with both SEM and TEM. The oxyfluorination with higher oxygen content produced more hydrophilic functional groups on the surface of multi-walled carbon nanotubes. The functional groups led to the well distribution and coating of PANi on the multi-walled carbon nanotubes resulting in the higher interfacial affinity between them. The uniform coating of PANi on MWCNTs by controlling the oxyfluorination conditions also played a crucial role in increasing the electrical conductivity of nanocomposites. The improved interfacial affinity resulted in the higher electromagnetic interference (EMI) SE of 47.03?dB based on the synergistic combination of the conductive components. The EMI shielding mechanism of PANi on MWCNTs suggested that EMI was mainly shielded by adsorption to avoid secondary EMI. 相似文献
The recent development in telecommunication technology has led electromagnetic interference (EMI) to a serious threat to both electronic devices and living beings. In this work, we designed a highly efficient EMI shielding material by taking advantage of both carbonaceous hybrid filler and double percolation phenomenon. Here, a flexible, lightweight microwave absorbing conductive polymer composite was fabricated by employing poly (ethylene‐co‐methyl acrylate) and ethylene octene copolymer (EMA/EOC) binary blend as the matrix and multiwall carbon nanotube carbon black (MWCNT/CB) hybrid filler as the conductive moiety. We investigated the effect of MWCNT content in the hybrid composite on mechanical, thermomechanical, electrical, and shielding efficiency. A total EMI shielding efficiency of ?37.4 dB in the X band region was attained with 20 wt% hybrid filler containing 50 wt% MWCNT along with promising mechanical properties. 相似文献
Carbon nanomaterials such as carbon nanotubes (CNTs), graphene and their hybrid have been studied extensively. Despite having excellent properties of CNTs and graphene have not yet been fully realized in the polymer composites. During fabrication agglomeration of CNTs and restacking of graphene is a serious concern that results in the degradation of properties of nanomaterials into the final composites. To improve the dispersion of CNTs and restacking graphene, in the present research work, we focused on the hybridization of graphene oxide and CNTs. Multiwalled carbon nanotubes (MWCNTs), functionalized carbon nanotubes (FCNTs), and graphene oxide-carbon nanotubes (GCNTs) reinforced acrylonitrile butadiene styrene (ABS) composites were prepared separately by vacuum filtration followed by hot compression molding. Further, dynamic mechanical analysis (DMA), and electromagnetic interference (EMI) shielding properties of ABS composites reinforced carbon nanofillers were investigated. The dynamic mechanical properties of polymers strongly depend on the adhesion of fillers and polymer, entanglement density of polymer chains in the presence of carbon fillers. The dynamic mechanical characteristics such as storage, loss modulus, and damping factor of prepared composites were significantly affected by the incorporation of MWCNTs, FCNTs, and GCNTs. Maximum EMI shielding effectiveness of −49.6 dB was achieved for GCNT-ABS composites which were highest compared to MWCNTs-ABS composites (−38.6 dB) and FCNTs-ABS composites (−36.7 dB) in the Ku band (12.4–18 GHz). These results depict the great potential of GCNTs-ABS composites to be used in various applications of efficient heat dissipative EMI shielding materials for electronic devices. 相似文献
The demand for flexible and freestanding electromagnetic interference(EMI) shielding materials are more and more urgent to combat with serious electromagnetic(EM) radiation pollution.Twodimensional Ti_3C_2T_x is considered as promising EMI shielding material to graphenes because of the low cost and high electrical conductivity.However,the shielding performance still needs to be optimized to decrease the reflection effectiveness(SE_R) and increase absorption effectiveness(SEA).Herein,we prepared Ti_3C_2T_x-bonded carbon black films with a porous structure.The SE_R decreased from 20 dB to12 dB and the SEA increased from 31 dB to 47 dB.The best EMI shielding effectiveness can be as high as60 dB with SE_A of 15 dB and SE_R of45 dB.Their calculated specific shielding effectiveness can be as high as8718 dB cm~2/g.These results indicate that the porous structure can enhance the absorption of the EMI shielding films,resulting from the enhanced scattering and reflectio n.Conseque ntly,this work provides a promising MXene-based EMI shielding film with lightweight and flexibility. 相似文献
Exploitation of cotton fabric as electromagnetic interference (EMI) shielding substrates have attracted a growing interest due to their desirable low carbon footprint, economic feasibility, and sustainability. Herein, a facile strategy was proposed for preparing a cellulose-based multifunctional PNIPAAm/PPy hydrogel/cotton (PPHC) EMI shielding composites with simultaneous high-efficient electro-photo-thermal conversion and comfort regulation functions. The PPHC was fabricated via in situ polymerization conductive PPy hydrogel on cotton substrate followed by deposition of PNIPAAm. Benefiting from the unique interconnected three-dimensional networked conductive structure of PPy hydrogel, the obtained PPHC composites exhibited high conductivity (15 mS/cm), and EMI shielding effectiveness (EMI SE?~?40 dB) in the frequency of 8.2–12.3 GHz. Moreover, the PNIPAAm coating endowed the composite fabrics with adjustable wettability performance in response to external temperature, leading to excellent comfort regulation performance. This work provided feasible avenue toward low cost and sustainability cotton-based EMI shielding composites with efficient EMI shielding and comfort regulation performance.
In this article,hybrid fillers with different dimensions,namely,2-dimensional (2-D) expanded graphite (EG) and 1-dimensional (1-D) multi-walled carbon nanotubes (CNTs),were added to aromatic nylon MXD6 matrix via melt-blending,to enhance its thermal and electrical conductivity as well as electromagnetic interference shielding effectiveness (EMI SE).For ternary composites of MXD6/EG/CNTs,the electrical conductivity reaches up nine orders of magnitude higher compared to that of the neat MXD6 sample,which tumed the polymer-based composites from an insulator to a conductor,and the thermal conductivity has been enhanced by 477% compared with that of neat MXD6 sample.Meanwhile,the EMI SE of ternary composite reaches ~50 dB at the overall filler loading of only 18 wt%.This work can provide guidance for the preparation of polymer composites with excellent thermal and electrical conductivity via using hybrid filler. 相似文献
The effects of variation in average diameter and surface area of nanocomposite fibers on electromagnetic interference (EMI) shielding of multi-walled carbon nanotubes (MWCNTs)/polyvinylpyrrolidone (PVP) fibers were investigated in this paper. The EMI shielding effectiveness of electrospun nanocomposite fibers were measured in the X-band frequency range 8.2–12.4 GHz. The electrical conductivity and EMI shielding behaviors of the nanocomposite fibers were reported as function of average diameter and surface area of MWCNTs/PVP nanocomposite fibers. The electrical conductivity measurements demonstrate using thinner nanocomposite fibers results in a lower limit of electrical resistivity, better electrical conductivity performance. The EMI shielding efficiency of thinner nanocomposite fibers increased up to 42 dB. The EMI shielding data for MWCNTs/PVP nanocomposite fibers with various average diameter and surface area showed that absorption was the major shielding mechanism and reflection was the secondary shielding mechanism. It can be related to higher specific surface area of thinner electrospun MWCNTs/PVP nanocomposite fibers that means more surface area for radiative scatter and absorption leading to higher EMI shielding performance. 相似文献
The use of plastic materials as housings for electronic equipment depends on the ability to change the plastic composition from an insulator into an electrical conductor. Because there is a wide latitude in the level of conductivity that is achievable in such a composition, it is important to be able to relate the level of electromagnetic interference (EMI) shielding attained to the bulk resistivity of the conductive plastic composition. This report describes the use of a dual chamber method for measuring the EMI shielding effectiveness of polymer-based compositions. The system described is capable of measuring the shielding effectiveness of filled composites, coated samples, flat and molded structures and gaskets, and the effect of void spaces and joints. The dynamic range of this system is 80 dB, which is sufficient for most plastic compositions. Finally, a correlation between shielding effectiveness and bulk resistivity for filled compositions is presented, based on plane wave analysis. Theoretical predictions and experimental results are shown to be in excellent agreement. 相似文献
This paper presents a solvent-based, mild method to prepare superhydrophobic, carbon nanofiber/PTFE-filled polymer composite coatings with high electrical conductivity and reports the first data on the effectiveness of such coatings as electromagnetic interference (EMI) shielding materials. The coatings are fabricated by spraying dispersions of carbon nanofibers and sub-micron PTFE particles in a polymer blend solution of poly(vinyledene fluoride) and poly(methyl methacrylate) on cellulosic substrates. Upon drying, coatings display static water contact angles as high as 158° (superhydrophobic) and droplet roll-off angles of 10° indicating self-cleaning ability along with high electrical conductivities (up to 309 S/m). 100 μm-thick coatings are characterized in terms of their EMI shielding effectiveness in the X-band (8.2-12.4 GHz). Results show up to 25 dB of shielding effectiveness, which changed little with frequency at a fixed composition, thus indicating the potential of these coatings for EMI shielding applications and other technologies requiring both extreme liquid repellency and high electrical conductivity. 相似文献
Conducting polymer composites should have a high dielectric constant and a high dissipation factor in the low and high frequency regions if they are to be used in charge storing devices, decoupling capacitors and electromagnetic interference shielding applications. Currently, extensive research is being carried out to enhance the dielectric constants of graphite-polymer, ceramic powder-polymer, metal powder-polymer and nanotube-polymer composites in the low frequency region. In this paper, we present the dielectric properties of styrene-acrylonitrile (SAN)-graphite sheets (GS) composites in the low and high frequency ranges. SAN-GS composites were prepared by the mixing process and by the hot compression mold technique. The composites showed a high dielectric constant and a high dissipation factor in the low and radio frequency region. Furthermore, the EMI shielding properties of these composites are evaluated in the radio frequency range. The conductivity and the dielectric constant of the SAN/GS composites increased with the addition of GS composites, and followed the power law model of percolation theory. The dielectric constant and the dissipation factor of the composites were analyzed according to the low and high frequency region. 相似文献
<正>Polypyrrole(PPy) shows a favorable application in the electromagnetic interference(EMI) shielding due to its good electrical conductivity and outstanding air stability.Conducting PPy films with high conductivity and good adhesion were successfully polymerized on the surface of insulating epoxy resin substrates using chemical polymerization.The factors affecting the properties of PPy films,such as the surface morphology,adhesion between PPy film and substrate,electrical conductivity,EMI shielding effectiveness(SE),were investigated.The adhesion was improved significantly through a three-step surface pretreatment of epoxy resin substrates including removing impurities,roughening,and surface modification with silane coupling agent.An enhancement in the conductivity of PPy films of about one order of magnitude was achieved by adding dopant in FeCl_3 solution.The higher the conductivity,the better the shielding effectiveness.Taking sodium p-toluenesulfonate doped PPy film as example,EMI SE was in the practically useful range of about 30 dB over a wide frequency range from 30 MHz to 1500 MHz.The PPy film samples were characterized by scanning electron microscopy (SEM),infrared spectra(IR),X-ray photoelectron spectroscopy(XPS) and the flange coaxial transmission device.The fourpoint probe method was used to measure conductivity of PPy films. 相似文献
As a critical action plan formulated for peaking carbon dioxide emissions, polymeric electromagnetic interference (EMI) shielding materials based on CO2 foaming technology have recently been attracting widespread attention in both research and industry, attributable to their efficient use of CO2, high specific strength, corrosion resistance and low-cost characteristics. In the past decade, the emergence of novel design concepts and preparation techniques for CO2 foaming technology has led to the development of new high-performance EMI shielding materials in this field. This review summarizes the research progress made to date on the fabrication of EMI shielding composite foams by supercritical carbon dioxide (scCO2) foaming. We also explore the structure-activity relationships between the component/distribution and EMI shielding properties. Additionally, the application prospects and development challenges of new EMI shielding composite foams are described. 相似文献