Articles de revues : « Insulating Matrix -Nanocomposites »

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Yu, Guang, Yujia Cheng et Zhuohua Duan. « Research Progress on Polymeric Inorganic Nanocomposites Insulating Materials ». Journal of Nanomaterials 2022 (3 décembre 2022) : 1–10. http://dx.doi.org/10.1155/2022/1757788.

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With the rapid development of power energy, electronic information, rail transit, and aerospace industries, nanocomposite dielectric materials have been widely used as new materials. Polymer/inorganic nanocomposite dielectric materials possess excellent physical and mechanical properties. In addition, numerous unique properties such as electricity, thermal, sound, light, and magnetic properties are exhibited by these materials. First, the macroscopic quantum tunneling effect, small-size effect, surface effect, and quantum-size effect of nanoparticles are introduced. There are a few anomalous changes in the physical and chemical properties of the matrix, which are caused by these effects. Second, the interaction mechanism between the nanoparticles and polymer matrix is introduced. These include infiltration adsorption theory, chemical bonding, diffusion theory, electrostatic theory, mechanical connection theory, deformation layer theory, and physical adsorption theory. The mechanism of action of the interface on the dielectric properties of the composites is summarized. These are the interface trap effect, interface barrier effect, and homogenization field strength effect. In addition, different interfacial structure models were used to analyze the specific properties of nanocomposite dielectric materials. Finally, the research status of the dielectric properties of nanocomposite dielectric materials is introduced.

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Park, Ji Sun, Young Sun Kim, Hyun-Jung Jung, Daseul Park, Jee Young Yoo, Jin Ho Nam et Yoon Jin Kim. « Polyethylene/Graphene Nanoplatelet Nanocomposite-Based Insulating Materials for Effective Reduction of Space Charge Accumulation in High-Voltage Direct-Current Cables ». Journal of Nanomaterials 2019 (24 mars 2019) : 1–11. http://dx.doi.org/10.1155/2019/9035297.

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We have demonstrated a straightforward hydrophobic surface modification of graphene nanoplatelets (GNPs) through a defect-healing process to fabricate well-dispersed insulating low-density polyethylene (LDPE)/GNP nanocomposites and have confirmed their effective suppression of space charge accumulation. Without any organic modifiers, GNPs containing oxygen-based functional groups at the edges were successfully reduced at optimal high-temperature defect-healing condition and modified to have hydrophobic surface properties similar to those of the LDPE matrix. The degree of dispersion and the reproducibility of the mechanically melt-mixed LDPE/GNP nanocomposites were immediately analyzed by thickness-normalized optical absorption measurement. In the LDPE matrix, below the percolation threshold concentration, well-dispersed GNP fillers effectively acted as trapping sites under high electric fields, resulting in the successful suppression of packet-like space charge accumulation (field enhancement factor=1.04 @ 0.1 wt% LDPE/GNP nanocomposite).

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Ramazanov, M. A., A. M. Rahimli et F. V. Hajiyeva. « The influence of titanium dioxide (TiO2) nanoparticles on the structure, optical and dielectric properties of polyvinyl chloride (PVC) ». Modern Physics Letters B 34, n^o 28 (10 juin 2020) : 2050310. http://dx.doi.org/10.1142/s0217984920503108.

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The tendency to improve the properties of insulating materials by incorporating inorganic nanoparticles has become necessary in order to design new insulation systems. In this study, PVC/TiO2-based nanocomposites with different loadings (3, 5 and 10 wt.%) of TiO2 nanoparticles were prepared by the solution mixing method. The morphology of the prepared nanocomposites was studied by Atomic Force Microscope (AFM). Experimentally, it was found that as the concentration increases, the size of the surface structural elements and particle size increases. Photoluminescence (PL) analysis of samples shows improvement compared to the pristine polymer. Furthermore, PL intensity for nanocomposites increases depending on the concentration and saturation occurs at a certain amount of titanium dioxide nanoparticles. The increase in luminescence intensity till a certain nanoparticle content is due to the growth of the luminescent surface area. Further saturation is explained by the increase in particle size with no increase or a slight reduction in surface area. Dielectric properties of nanocomposites were studied. It was found that dielectric permittivity of the materials increases as the nanoparticle volume content increases and it reaches at its highest value for the nanocomposites with 3% nanoparticle content. The optical properties of the polymer and nanocomposite films were studied in the region 200 nm to 600 nm. It was found that the PVC/TiO2 nanocomposites showed enhancement in the absorbance intensities which was more significant for the nanocomposites with higher nanoparticle content compared to the pristine polymer. Furthermore, absorption spectra were used to calculate the optical bandgap of the prepared nanocomposite films and redshift observed in the calculated values of bandgap for nanocomposites. Consequently, it was proved that by incorporating TiO2 nanoparticles into the polymer matrix, the spectral region of the samples can be expanded resulting in broadened application of such systems in various fields of science and technology.

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Lin, Jia Qi, Ying Liu, Wen Long Yang et Hui Lin. « Investigation on the Morphology and Dielectric Properties of PI/SiO₂ Nanocomposite Films ». Advanced Materials Research 1015 (août 2014) : 250–54. http://dx.doi.org/10.4028/www.scientific.net/amr.1015.250.

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Polyimide nanocomposite insulating materials are widely used in electrical and electron engineering owing to their outstanding electrical, mechanical, thermal, and wear-resistance properties. Polyimide/silica (PI/SiO2) nanocomposites have been prepared by the polymerization process of adding tetraethoxysilane (TEOS) and the coupling agent isocyanatopropyltriethoxysilane (ICTOS) in polyimide. The effects of SiO2addition on the microstructure and the dielectric property of nanocomposite films were investigated. It was found that the silica particles were well dispersed in PI matrix and the sizes of SiO2particles in the hybrid films range from 20 nm to 30 nm for 5-15 wt% SiO2loading in the matrix. The dielectric constant and the dielectric loss (tan δ) of these films increased with the increase of the content of silica particles.

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Zhou, Yongcun, Shihu Yu, Huan Niu et Feng Liu. « Synergistic Improvement in Thermal Conductivity of Polyimide Nanocomposite Films Using Boron Nitride Coated Copper Nanoparticles and Nanowires ». Polymers 10, n^o 12 (19 décembre 2018) : 1412. http://dx.doi.org/10.3390/polym10121412.

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Electronic devices are increasingly dense, underscoring the need for effective thermal management. A polyimide (PI) matrix nanocomposite film combining boron nitride (BN)-coated copper nanoparticles (CuNPs@BN) and nanowires (CuNWs@BN) was fabricated by a flexible and fast technique for enhanced thermal conductivity and the dielectric properties of nanocomposite films. The thermal conductivity of (CuNPs-CuNWs)@BN/PI composite comprising 10 wt % filler loading rose to 4.32 W/mK, indicating a nearly 24.1-fold increase relative to the value obtained for pure PI matrix. The relative permittivity and dielectric loss approximated 4.92 and 0.026 at 1 MHz, respectively. The results indicated that the surface modification of CuNPs and CuNWs by introducing a ceramic insulating layer BN effectively promoted the formation of thermal conductive networks of nanofillers in the PI matrix. This study enabled the identification of appropriate modifier fillers for polymer matrix nanocomposites to improve electronic applications.

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Sagar, Rohan, Akash Kumar, Rajesh Kumar Raghav et M. S. Gaur. « Investigations on Piezoelectric, Dielectric and Mechanical Properties of PVDF/PVC/GO Nanocomposites ». ECS Journal of Solid State Science and Technology 12, n^o 8 (1 août 2023) : 083011. http://dx.doi.org/10.1149/2162-8777/aceeb4.

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In this study, the hardness of polyvinylidene fluoride (PVDF), PVC and PVDF/PVC/GO (2.0 wt%) was estimated using piezoelectric and dielectric properties. The structure morphology was analyzed by Fourier transform infrared spectroscopy (FTIR). With the help of the solution casting technique, GO nanofiller were incorporated into PVDF/PVC matrix to prepare nanocomposites. In the case of PVDF/PVC/GO nanocomposites (2.0 wt%), the d33 coefficient is comparatively higher. PVDF have lower dielectric constant, however, may be due to interfacial polarization occurring at the spherulites and at the polymer/filler interfaces. The achieved lower loss tangent (tanδ) for PVDF compared to PVDF/PVC and PVDF/PVC/GO (2.0 wt%) nanocomposites is attributed to PVDF highly insulating nature. The PVDF/PVC/GO (2.0 wt%) nanocomposite exhibited a d33 value of ∼26 pm V−1, which was significantly higher than pure PVDF and PVDF/PVC.

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BUZNIKOV, N. A., I. T. IAKUBOV, A. L. RAKHMANOV, K. I. KUGEL et A. O. SBOYCHAKOV. « HIGH-FREQUENCY RESPONSE AND VOLTAGE NOISE IN MAGNETIC NANOCOMPOSITES ». International Journal of Modern Physics B 23, n^o 20n21 (20 août 2009) : 4216–33. http://dx.doi.org/10.1142/s0217979209063389.

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We study the noise spectra and high-frequency permeability of inhomogeneous magnetic materials consisting of single-domain magnetic nanoparticles embedded into an insulating matrix. Possible mechanisms of 1/f voltage noise in phase-separated manganites is analyzed. The material is modelled by a system of small ferromagnetic metallic droplets (magnetic polarons or ferrons) in insulating antiferromagnetic or paramagnetic matrix. The electron transport is related to tunnelling of charge carriers between droplets. One of the sources of the 1/f noise in such a system stems from fluctuations of the number of droplets with extra electron. In the case of strong magnetic anisotropy, the 1/f noise can arise also due to the fluctuations of the magnetic moments of ferrons. The high frequency magnetic permeability of nanocomposite film with magnetic particles in insulating non-magnetic matrix is studied in detail. The case of strong magnetic dipole interaction and strong magnetic anisotropy of ferromagnetic granules is considered. The composite is modelled by a cubic regular array of ferromagnetic particles. The high-frequency permeability tensor components are found as a functions of frequency, temperature, ferromagnetic phase content, and magnetic anisotropy. The results demonstrate that magnetic dipole interaction leads to a shift of the resonance frequencies towards higher values, and nanocomposite film could have rather high value of magnetic permeability in the microwave range.

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Yang, Jae Kyo, D. J. Park, J. Kim, Si Young Chang, Chung Hyo Lee, Tohru Sekino, Koichi Niihara et Yong Ho Choa. « Preparation and Evaluation of Metal/Ceramic Nanocomposites for High Frequency Inductive Devices ». Key Engineering Materials 317-318 (août 2006) : 869–72. http://dx.doi.org/10.4028/www.scientific.net/kem.317-318.869.

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Fe/MgO nanocomposites, which are applicable to high frequency electronic devices, were fabricated by ultrasonic spray pyrolysis and selective reduction processes. Transmission electron micrographs showed that nano ferromagnetic Fe particles were isolated by MgO insulating matrix. With the increase of the reduction temperature, the particle size and saturation magnetization of the nanocomposites increased, which resulted in the decrease of the coercive force and the increase of the permeability. Furthermore, the ferromagnetic resonance peak of the nanocomposites was not observed up to 9 GHz.

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Han, Long, Zhaobo Wang, Jing Hua et Jieting Geng. « Well-Distributed Polysilsesquioxane-Modified Carbon Nanotubes for Thermal Conductive Insulating Silicone Rubbers ». Advances in Polymer Technology 2022 (27 août 2022) : 1–9. http://dx.doi.org/10.1155/2022/9115873.

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Despite carbon nanotubes (CNTs) have garnered tremendous research interests for enhancing the electrical and thermal conductivity of polymers, it is still a considerable challenge to achieve the uniform dispersion of carbon nanotubes in polymer matrix. Herein, inspired by the mussel-inspired chemistry, we adopted the strategy of coating CNTs with polydopamine. And the polysilsesquioxane-modified CNTs (CNTs-PSQ) were obtained based on the click chemistry reaction. The FT-IR, Raman, XRD, and TGA collectively demonstrated the successful modification of PSQ on the surface of CNTs. The incorporation of PSQ could significantly improve the dispersion of CNTs in the silicon rubbers, and a strong interfacial interaction was formed between CNTs-PSQ and silicon rubber matrix, as observed from TEM images of silicon rubber/CNTs-PSQ nanocomposites. Meanwhile, compared with the nanocomposites with neat CNTs, the ones with CNTs-PSQ exhibited simultaneously improved electrical conductivity and insulating performance. This strategy proposed for the preparation of PSQ-modified CNTs provides insights toward highly insulating and thermal conducting polymers.

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Kim, Do-Kyung, Muhammet S. Toprak, Maria Mikhaylova, Yun Suk Jo, Steven J. Savage, Hyung Bock Lee, Thomas Tsakalakos et Mamoun Muhammed. « Polymeric Nanocomposites of Complex Ferrite ». Solid State Phenomena 99-100 (juillet 2004) : 165–68. http://dx.doi.org/10.4028/www.scientific.net/ssp.99-100.165.

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The influence of mixtures of Ni0.5Zn0.4Cu0.1Fe2O4, CoFe2O4, and graphite on the permeability, permittivity and microwave absorption properties in a composite embedded with insulating polymeric matrix, that can be used for X- and P-band radar absorption, has been investigated. Thermodynamic modelling of the complex ferrite system has been demonstrated by the controlled simultaneous coprecipitation of all ions inolved in the composite in the selected working pH ranges. The method employed is very convenient for the synthesis of multicomponent systems with a homogenous distribution of compositions.

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ZHU, LIU-JUAN, WEN-ZHONG CAI, BO-QIN GU et SHAN-TUNG TU. « TUNNELING PERCOLATION MODEL OF THE ELECTRICAL CONDUCTIVITY OF PARTICULATE NANOCOMPOSITES ». Modern Physics Letters B 23, n^o 10 (20 avril 2009) : 1273–79. http://dx.doi.org/10.1142/s0217984909019399.

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The nanocomposites consisting of conducting nanoparticles and insulating matrix are studied. A tunneling percolation model is developed for their peculiar conduction behavior based on the equivalent-particle concept. It provides a clear microstructure-property correlation by combining many-particle statistics, effective-medium theory, and classical percolation theory. Its availability is assessed by available experimental data.

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Ongaro, Greta, Alessandro Pontefisso, Elena Zeni, Francesco Lanero, Alessia Famengo, Federico Zorzi, Mirco Zaccariotto et al. « Chemical and Mechanical Characterization of Unprecedented Transparent Epoxy–Nanomica Composites—New Model Insights for Mechanical Properties ». Polymers 15, n^o 6 (15 mars 2023) : 1456. http://dx.doi.org/10.3390/polym15061456.

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Two nanomicas of similar composition, containing muscovite and quartz, but with different particle size distributions, have been used to prepare transparent epoxy nanocomposites. Their homogeneous dispersion, due to the nano-size, was achieved even without being organically modified, and no aggregation of the nanoparticles was observed, thus maximizing the specific interface between matrix and nanofiller. No exfoliation or intercalation has been observed by XRD, despite the significant dispersion of the filler in the matrix which produced nanocomposites with a loss in transparency in the visible domain of less than 10% in the presence of 1% wt and 3% wt of mica fillers. The presence of micas does not affect the thermal behavior of the nanocomposites, which remains similar to that of the neat epoxy resin. The mechanical characterization of the epoxy resin composites revealed an increased Young’s modulus, whereas tensile strength was reduced. A peridynamics-based representative volume element approach has been implemented to estimate the effective Young’s modulus of the nanomodified materials. The results obtained through this homogenization procedure have been used as input for the analysis of the nanocomposite fracture toughness, which has been carried out by a classical continuum mechanics–peridynamics coupling approach. Comparison with the experimental data confirms the capability of the peridynamics-based strategies to properly model the effective Young’s modulus and fracture toughness of epoxy-resin nanocomposites. Finally, the new mica-based composites exhibit high values of volume resistivity, thus being excellent candidates as insulating materials.

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Siriyong, Tutchawan, Wirunya Keawwattana et Jin Kuk Kim. « Influence of Graphene Nanoplatelet Filling in Thermoplastic Natural Rubber Antistatic Nanocomposite Using Combination of Solution and Melt Mixing Method ». Advanced Materials Research 1101 (avril 2015) : 57–61. http://dx.doi.org/10.4028/www.scientific.net/amr.1101.57.

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A simple combination of solution mixing and melt mixing method for the preparation of fully exfoliated and dispersed graphene nanoplatelet (xGnP) in thermoplastic natural rubber (TPNR) as NBR/PVC (NVC) blend (70:30) has been successfully demonstrated. Two different types of H5−xGnP (~53 layers) and C750−xGnP (~16 layers) were used in this study. The amount of xGnP filled in the nanocomposite has been varied from 0-3 phr. The electrical and mechanical properties of filled TPNR nanocomposites were increased with the increase in both of xGnP types loading. The results suggest that the process provides us a much better dispersion and exfoliation of xGnP into the matrix than direct mixing method. With comparing xGnP types, the number of layer stacked xGnP has significant effect on the tensile strength and electrical conductivity of nanocomposites, the lower the number of layer stacked xGnP, the higher mechanical and electrical properties. The tensile strength of pre−dispersed H5− and C750−xGnP−NR/NVC nanocomposites at 3 phr loading were increased by ~16 % and ~34% respectively compared to conventional direct mixing. While dramatic enhancement of electrical conductivity for the pre−dispersed H5− and C750−xGnP/TPNR nanocomposites has been changed from insulating range to antistatic range.

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Cordoba, Aldo, Eric Mauricio Rivera-Muñoz, Rodrigo Velázquez-Castillo et Karen Esquivel. « PDMS/TiO2 and PDMS/SiO2 Nanocomposites : Mechanical Properties’ Evaluation for Improved Insulating Coatings ». Nanomaterials 13, n^o 10 (22 mai 2023) : 1699. http://dx.doi.org/10.3390/nano13101699.

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The use of nanoparticles (NPs) as reinforcements in polymeric coatings allows for direct interaction with the polymeric chains of the matrix, resulting in a synergistic process through physical (electrostatic forces) and chemical interactions (bond formation) for the improvement of the mechanical properties with relatively low weight concentrations of the NPs. In this investigation, different nanocomposite polymers were synthesized from the crosslinking reaction of the hydroxy-terminated polydimethylsiloxane elastomer. Different concentrations (0, 2, 4, 8, and 10 wt%) of TiO2 and SiO2 nanoparticles synthesized by the sol-gel method were added as reinforcing structures. The crystalline and morphological properties of the nanoparticles were determined through X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM). The molecular structure of coatings was through infrared spectroscopy (IR). The crosslinking, efficiency, hydrophobicity, and adhesion degree of the study groups were evaluated with gravimetric crosslinking tests, contact angle, and adhesion tests. It was observed that the crosslinking efficiency and surface adhesion properties of the different nanocomposites obtained were maintained. A slight increase in the contact angle was observed for the nanocomposites with 8 wt% compared to the polymer without reinforcements. The mechanical tests of indentation hardness and tensile strength following the ASTM E-384 and ISO 527 standards, respectively, were performed. As the nanoparticle concentration increased, a maximum increase of 157% in Vickers hardness, 71.4% in elastic modulus, and 80% in tensile strength was observed. However, the maximum elongation remained between 60 and 75%, ensuring that the composites did not become brittle.

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Thabet, Ahmed, et Youssef Mobarak. « Experimental Dielectric Measurements for Cost-fewer Polyvinyl Chloride Nanocomposites ». International Journal of Electrical and Computer Engineering (IJECE) 5, n^o 1 (1 février 2015) : 13. http://dx.doi.org/10.11591/ijece.v5i1.pp13-22.

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Polymer nanocomposites possess promising high performances as engineering materials, if they are prepared and fabricated properly. In this research, it has been processed samples of nanocomposite polymers as electrical insulating materials for application on the electric power cables by using the latest techniques of nanotechnology. This paper has been investigated enhanced dielectric and electrical properties of Polyvinyl chloride PVC as matrix have shown that trapping properties are highly modified by the presence of costless nanofillers clay and fumed silica. An experimental work for dielectric loss and capacitance of the new nanocomposite materials have been investigated and compared with unfilled industrial materials. It is found that a good correlation exists in respect of capacitance and dielectric loss values measured with percentage of nanofillers. Thus, it has been investigated the influence of costless nanofillers material and its concentration on dielectric properties of industrial polymers-based composite systems. A comparative study is performed between the unfilled base polymers, the systems containing one type of nanoparticles clay or fumed silica inside the host polymer with various concentrations.

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Rylkov, Vladimir, Alexander Taldenkov, Vyacheslav Demin, Alexander Vedeneev, Alexander Bugaev, Alexander Granovsky, Alexander Sitnikov et al. « Properties of Nanocomposites With Different Concentrations of Magnetic Ions in an Insulating Matrix ». IEEE Magnetics Letters 10 (2019) : 1–4. http://dx.doi.org/10.1109/lmag.2019.2955060.

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McLachlan, David S., et Godfrey Sauti. « The AC and DC Conductivity of Nanocomposites ». Journal of Nanomaterials 2007 (2007) : 1–9. http://dx.doi.org/10.1155/2007/30389.

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The microstructures of binary (conductor-insulator) composites, containing nanoparticles, will usually have one of two basic structures. The first is the matrix structure where the nanoparticles (granules) are embedded in and always coated by the matrix material and there are no particle-particle contacts. The AC and DC conductivity of this microstructure is usually described by the Maxwell-Wagner/Hashin-Shtrikman or Bricklayer model. The second is a percolation structure, which can be thought to be made up by randomly packing the two types of granules (not necessarily the same size) together. In percolation systems, there exits a critical volume fraction below which the electrical properties are dominated by the insulating component and above which the conducting component dominates. Such percolation systems are best analyzed using the two-exponent phenomenological percolation equation (TEPPE). This paper discusses all of the above and addresses the problem of how to distinguish among the microstructures using electrical measurements.

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Abdul Razak, Nurul Iman, Noor Izyan Syazana Mohd Yusoff, Mohd Hafizi Ahmad, Muzafar Zulkifli et Mat Uzir Wahit. « Dielectric, Mechanical, and Thermal Properties of Crosslinked Polyethylene Nanocomposite with Hybrid Nanofillers ». Polymers 15, n^o 7 (29 mars 2023) : 1702. http://dx.doi.org/10.3390/polym15071702.

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Crosslinked polyethylene (XLPE) nanocomposite has superior insulation performance due to its excellent dielectric, mechanical, and thermal properties. The incorporation of nano-sized fillers drastically improved these properties in XLPE matrix due to the reinforcing effect of interfacial region between the XLPE–nanofillers. Good interfacial strength can be further improved by introducing a hybrid system nanofiller as a result of synergistic interaction between the nanofiller relative to a single filler system. Another factor affecting interfacial strength is the amount of hybrid nanofiller. Therefore, the incorporation amount of hybridising layered double hydroxide (LDH) with aluminium oxide (Al2O3) nanofiller into the XLPE matrix was investigated. Herein, the influence of hybrid nanofiller content and the 1:1 ratio of LDH to Al2O3 on the dielectric, mechanical, and thermal properties of the nanocomposite was studied. The structure and morphology of the XLPE/LDH-Al2O3 nanocomposites revealed that the hybridisation of nanofiller improved the dispersion state. The dielectric, mechanical, and thermal properties, including partial discharge resistance, AC breakdown strength, and tensile properties (tensile strength, Young’s modulus, and elongation at break) were enhanced since it was influenced by the synergetic effect of the LDH-Al2O3 nanofiller. These properties were increased at optimal value of 0.8 wt.% before decreasing with increasing hybrid nanofiller. It was found that the value of PD magnitude improvement went down to 47.8% and AC breakdown strength increased by 15.6% as compared to pure XLPE. The mechanical properties were enhanced by 14.4%, 31.7%, and 23% for tensile strength, Young’s modulus, and elongation at break, respectively. Of note, the hybridisation of nanofillers opens a new perspective in developing insulating material based on XLPE nanocomposite.

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Ferreira Braga, Natália, Henrique Morales Zaggo, Larissa Stieven Montagna et Fabio Roberto Passador. « Effect of Carbon Nanotubes (CNT) Functionalization and Maleic Anhydride-Grafted Poly(trimethylene terephthalate) (PTT-g-MA) on the Preparation of Antistatic Packages of PTT/CNT Nanocomposites ». Journal of Composites Science 4, n^o 2 (24 avril 2020) : 44. http://dx.doi.org/10.3390/jcs4020044.

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Electronic devices require the use of antistatic packing to prevent electrostatic discharge during their storage or transport. Poly (trimethylene terephthalate) (PTT) is a polyester with excellent properties and can be a good candidate for this application. To make this insulating polymer an extrinsic conductor, carbon nanotubes (CNT) can be added to reduce the electrical resistivity of the nanocomposites. In order to facilitate the CNT distribution on polymeric matrix, it was proposed a chemical functionalization using nitric acid for the creation of functional groups on its surface. Moreover, the PTT matrix was modified with a compatibilizer agent based on maleic anhydride grafted PTT (PTT-g-MA), to improve interfacial adhesion between the nanofiller and matrix. In this work, nanocomposites based on PTT/PTT-g-MA/CNT were prepared by extrusion process, with 0.5 wt% and 1.0 wt% of CNT and functionalized CNT. CNT was characterized by stability dispersion in water, Raman spectroscopy, FTIR and XPS analysis, which prove the success of functionalization. The nanocomposites were evaluated by thermal analysis, tensile tests, electrical conductivity, and morphological analysis. The CNT functionalization and the addition of PTT-g-MA increased the dispersion and distribution of CNT in the PTT matrix. The electrical properties show that this material can be used as an antistatic packaging.

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Volponi, Ruggero, Felice De Nicola et Paola Spena. « Nanocomposites for new Functionalities in Multiscale Composites ». MATEC Web of Conferences 188 (2018) : 01027. http://dx.doi.org/10.1051/matecconf/201818801027.

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This work describes the developing of multiscale composites with inherent health monitoring functionality. Nanotubes tend to form electrically conductive networks when embedded even at low concentrations in traditional insulating polymers. By dispersing nanotubes it is possible to obtain a class of polymers that show a piezoresistive behavior. By using that kind of piezoresistive polymer as matrix in fiber reinforced composites, it is possible to develop multiscale composites with an inherent health monitoring functionality. Two different approaches have been developed to obtain a multiscale composite able to monitor the tensional states of composites. In a first manner has been used a thermosetting resin filled with a mixture of nanotubes and graphene and a specific method has been developed to impregnate carbon fiber fabrics with that nanocharged resin. A second idea was to insert a thermoplastic nanocharged thin film into a glass fiber reinforced composites.

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Mat Desa, Mohd Shaiful Zaidi, Azman Hassan et Agus Arsad. « The Influence of Carbon Nanotubes Contents on Electrical and Flammability Properties of Poly(Lactic Acid)/Multiwalled Carbon Nanotubes Nanocomposites ». Solid State Phenomena 268 (octobre 2017) : 365–69. http://dx.doi.org/10.4028/www.scientific.net/ssp.268.365.

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The effects of carboxylic functionalized multi-walled carbon nanotubes (CNT) contents on electrical and flammability properties of poly(lactic) acid/CNT nanocomposites were investigated. The PLA/CNT nanocomposites were prepared by melt-blending method, where the CNT contents were varied from 1 to 9 phr. From flammability properties analysis, nanocomposites with 9 phr CNT showed the highest limiting oxygen index (LOI) of 26.5 vol% as compared to 19.5 vol% of neat PLA. All nanocomposites with higher than 5 phr CNT contents also passed the V0 class of UL-94 vertical burning test rating. The direct current electrical test revealed that the electrical conductivity increases by approximately seven orders of magnitude from 2.19 × 10-11 S/m of neat PLA to 2.00 × 10-4 S/m for PLA/CNT nanocomposites with 5 phr CNT contents. The electrical conductivity of PLA/CNT continues to increase beyond 5 phr contents, with 2.26 × 10-3 S/m and 4.29 × 10-3 S/m respectively for 7 and 9 phr contents. The good dispersion of CNT leads to formation of electron conducting CNT networks throughout the insulating PLA matrix.

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Guadagno, Liberata, Marialuigia Raimondo, Carlo Naddeo, Luigi Vertuccio, Salvatore Russo, Generoso Iannuzzo et Elisa Calabrese. « Rheological, Thermal and Mechanical Characterization of Toughened Self-Healing Supramolecular Resins, Based on Hydrogen Bonding ». Nanomaterials 12, n^o 23 (5 décembre 2022) : 4322. http://dx.doi.org/10.3390/nano12234322.

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This paper proposes the design of toughened self-healing supramolecular resins able to fulfill functional and structural requirements for industrial applications. These new nanocomposites are based on compounds acting as promotors of reversible self-healing interactions. Electrically conductive carbon nanotubes, selected among those allowing to reach the electrical percolation threshold (EPT) with a very low amount of nanofiller, were dispersed in the self-healing polymeric matrix to contrast the electrical insulating properties of epoxy matrices, as required for many applications. The formulated supramolecular systems are thermally stable, up to 360 °C. Depending on the chemical formulation, the self-healing efficiency η, assessed by the fracture test, can reach almost the complete self-repairing efficiency (η = 99%). Studies on the complex viscosity of smart nanocomposites highlight that the effect of the nanofiller dominates over those due to the healing agents. The presence of healing compounds anchored to the hosting epoxy matrix determines a relevant increase in the glass transition temperature (Tg), which results in values higher than 200 °C. Compared to the unfilled matrix, a rise from 189 °C to 223 °C is found for two of the proposed formulations.

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Ilyin, Sergey O., et Sergey V. Kotomin. « Effect of Nanoparticles and Their Anisometry on Adhesion and Strength in Hybrid Carbon-Fiber-Reinforced Epoxy Nanocomposites ». Journal of Composites Science 7, n^o 4 (7 avril 2023) : 147. http://dx.doi.org/10.3390/jcs7040147.

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Carbon-fiber-reinforced plastics are composite materials with record-high specific strength, which depends on the efficiency of stress redistribution between the reinforcing fibers by the polymer matrix. The problem is the accurate assessment of adhesion in the carbon fiber–polymer matrix system since it affects the overall strength of the composite. This paper provides a novel electrochemical method for determining adhesion by estimating the critical length of carbon fibers that protrude above the fracture surface of the fiber-reinforced composite using their electrical conductivity and insulating properties of the polymer matrix. The method has been successfully applied to evaluate adhesion in carbon plastics having an epoxy matrix filled with nanoparticles of different anisometry: carbon nanotubes, organomodified montmorillonite, or detonation nanodiamonds. In addition to adhesion measurements, the effect of nanoparticles on the viscosity of epoxy binder, its impregnation efficiency of carbon fibers, curing, glass transition, and tensile strength of fiber-reinforced composites was estimated. Nanodiamonds at a mass fraction of 0.1% proved to be the most effective for improving the quality of epoxy carbon plastics, increasing fiber–matrix adhesion by 2.5 times, tensile strength by 17%, and not decreasing the glass transition temperature.

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ZHOU, M., B. WANG, X. JIANG, A. A. ZAKHIDOV, J. P. FERRARIS, D. AZUNSKIS et L. HANLEY. « SYNTHESIS OF PbS NANOCRYSTAL/FUNCTIONALIZED CONDUCTING POLYMERS FOR PLASTIC SOLAR CELLS ». International Journal of Nanoscience 10, n^o 03 (juin 2011) : 521–32. http://dx.doi.org/10.1142/s0219581x11008320.

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Lead-based nanocrystals (NCs) are promising materials for high-efficiency solar cells since they are able to generate multiexcitons with high efficiency. One complication of utilizing these NCs is the insulating ligands capping their surfaces. In this paper, we have successfully developed and characterized a phosphonate-functionalized poly-3-hexylthiophene (POP3HT-50) and used it in the direct synthesis of PbS NCs within the polymeric host matrix without extraneous ligands. Devices made of POP3HT-50/PbS nanocomposites show an order of magnitude improvement in η when compared to that reported for a P3HT/ PbS device (η = 0.011% versus 0.001%). The improved performance is consistent with better electronic contact between PbS NCs and POP3HT-50.

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Luo, E. Z., J. B. Xu, W. Wu, I. H. Wilson, B. Zhao et X. Yan. « Identifying conducting phase from the insulating matrix in percolating metal-insulator nanocomposites by conducting atomic force microscopy ». Applied Physics A : Materials Science & ; Processing 66, n^o 7 (1 mars 1998) : S1171—S1174. http://dx.doi.org/10.1007/s003390051320.

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Chen, Jie, Xiaoyong Zhang, Xiao Yang, Chuanyang Li, Yifei Wang et Weixing Chen. « High Breakdown Strength and Energy Storage Density in Aligned SrTiO3@SiO2 Core–Shell Platelets Incorporated Polymer Composites ». Membranes 11, n^o 10 (30 septembre 2021) : 756. http://dx.doi.org/10.3390/membranes11100756.

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Dielectric nanocomposites with high energy storage density (Ue) have a strong attraction to high-pulse film energy-storage capacitors. Nevertheless, low breakdown strengths (Eb) and electric displacement difference (Dmax-Drem) values of nanocomposites with incorporating the randomly distributed high dielectric constant additions, give rise to low Ue, thereby hindering the development of energy-storage capacitors. In this study, we report on newly designed SrTiO3@SiO2 platelets/PVDF textured composites with excellent capacitive energy storage performance. SrTiO3@SiO2 platelets are well oriented in the PVDF when perpendicular to the electric field with the assistance of shear force in the flow drawing process to establish microscopic barriers in an inorganic–polymer composite that is able to substantially improve the Eb of composites and enhance the Ue accordingly. Finite element simulation demonstrates that the introduction of the highly insulating SiO2 coating onto the SrTiO3 platelets effectively alleviates the interface dielectric mismatch between filler and PVDF matrix, resulting in a reduction in the interface electric field distortion. The obtained composite film with optimized paraelectric SrTiO3@SiO2 platelets (1 vol%) exhibited a maximum Dmax-Drem value of 9.14 μC cm−2 and a maximum Ue value of 14.4 J cm−3 at enhanced Eb of 402 MV m−1, which are significantly superior to neat PVDF and existing dielectric nanocomposites.

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AbdulKadir, H. K. « Preparation and Dielectric Properties of Polyaniline-Coated Magnetite Nanocomposites ». Asian Journal of Chemistry 32, n^o 2 (30 décembre 2019) : 385–90. http://dx.doi.org/10.14233/ajchem.2020.22352.

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The conductive polymers such as polyaniline (PANI) exhibit considerable electrical conductive properties. The coating of PANI with magnetic (Fe3O4) nanoparticles formed composites (PANI/Fe3O4) with required dielectric properties. The morphology result study of PANI/Fe3O4 by field emission scanning electron microscope (FESEM) indicate the presence of PANI with tubes like structure containing different wt % of Fe3O4 nanoparticles (5, 15, 25 wt %). The structural pattern investigated by XRD revealed the presence of Fe3O4 nanoparticles at 2θ = 35.58º, while the amorphous structure indicates the presence of PANI matrix. However, the chemical bonding analysis using FTIR shows chemical conjugation of bonds at 3336, 3300 and 3277 cm-1 due to presence of NH group in PANI and OH group in Fe3O4 nanoparticles, while presence of 504 and 526 cm-1 suggesting that Fe3O4 nanoparticles are present in the composites materials. The dielectric properties study by 4-point probe and VSM shows that PANI and PANI/Fe3O4 nanocomposites exhibit good electrical properties (1.55 to 1.35 S/cm) which are decreasing with increase of Fe3O4 nanoparticles, may be resulting due to insulating behaviour of the magnetic nanoparticles, while the magnetic properties of PANI/Fe3O4 nanocomposites indicate super paramagnetic properties with saturation magnetization of (59.4, 5.96, 11.94 and 15.43 emus/g).

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Tashkinov, M. A., A. D. Dobrydneva, V. P. Matveenko et V. V. Silberschmidt. « Modeling the Effective Conductive Properties of Polymer Nanocomposites with a Random Arrangement of Graphene Oxide Particles ». PNRPU Mechanics Bulletin, n^o 2 (15 décembre 2021) : 167–80. http://dx.doi.org/10.15593/perm.mech/2021.2.15.

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Сomposite materials are widely used in various industrial sectors, for example, in the aviation, marine and automotive industries, civil engineering and others. Methods based on measuring the electrical conductivity of a composite material have been actively developed to detect internal damage in polymer composite materials, such as matrix cracking, delamination, and other types of defects, which make it possible to monitor a composite’s state during its entire service life. Polymers are often used as matrices in composite materials. However, almost always pure polymers are dielectrics. The addition of nanofillers, such as graphene and its derivatives, has been successfully used to create conductive composites based on insulating polymers. The final properties of nanomodified composites can be influenced by many factors, including the type and intrinsic properties of nanoscale objects, their dispersion in the polymer matrix, and interphase interactions. The work deals with modeling of effective electric conductive properties of the representative volume elements of nanoscale composites based on a polymer matrix with graphene oxide particles distributed in it. In particular, methods for evaluating effective, electrically conductive properties have been studied, finite element modelling of representative volumes of polymer matrices with graphene oxide particles have been performed, and the influence of the tunneling effect and the orientation of inclusions on the conductive properties of materials have been investigated. The possibility of using models of resistive strain gauges operating on the principle of the tunneling effect is studied. Based on the finite-element modeling and graph theory tools, we created approaches for estimating changes in the conductive properties of the representative volume elements of a nanomodified matrix subjected to mechanical loading.

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Agbabiaka, Okikiola Ganiu, Miracle Hope Adegun, Kit-Ying Chan, Heng Zhang, Xi Shen et Jang-Kyo Kim. « BN-PVDF/rGO-PVDF Laminate Nanocomposites for Energy Storage Applications ». Nanomaterials 12, n^o 24 (19 décembre 2022) : 4492. http://dx.doi.org/10.3390/nano12244492.

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The increasing demand for high energy storage devices calls for concurrently enhanced dielectric constants and reduced dielectric losses of polymer dielectrics. In this work, we rationally design dielectric composites comprising aligned 2D nanofillers of reduced graphene oxide (rGO) and boron nitride nanosheets (BNNS) in a polyvinylidene fluoride (PVDF) matrix through a novel press-and-fold technique. Both nanofillers play different yet complementary roles: while rGO is designed to enhance the dielectric constant through charge accumulation at the interfaces with polymer, BNNS suppress the dielectric loss by preventing the mobility of free electrons. The microlaminate containing eight layers each of rGO/PVDF and BNNS/PVDF films exhibits remarkable dielectric performance with a dielectric constant of 147 and an ultralow dielectric loss of 0.075, due to the synergistic effect arising from the alternatingly electrically conductive and insulating films. Consequently, a maximum energy density of 3.5 J/cm3—about 18 times the bilayer composite counterpart—is realized. The high thermal conductivities of both nanofillers and their alignment endow the microlaminate with an excellent in-plane thermal conductivity of 6.53 Wm−1K−1, potentially useful for multifunctional applications. This work offers a simple but effective approach to fabricating a composite for high dielectric energy storage using two different 2D nanofillers.

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Jamail, N. A. M., M. A. M. Piah, Nor Asiah Muhamad, Hanafiah Kamarden et Qamarul Ezani Kamarudin. « Application of PDC Analysis to Identify Effect of Electrical Tracking on Conductivity of LLDPE-NR Nanocomposite ». Applied Mechanics and Materials 785 (août 2015) : 325–29. http://dx.doi.org/10.4028/www.scientific.net/amm.785.325.

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Polymeric nanocomposites are widely used for high voltage outdoor insulating application due to their good electrical performance. Recently, SiO2, TiO2 and MMT nanofillers are being used as filler because there are listed as main nanofiller commonly used in electrical engineering. Natural rubber (NR) was used because the nature of the interphase is found to affect viscoelasticity and it develops several interphases with the Linear Low-Density Polyethylene (LLDPE) matrix. One of the problems associated with outdoor polymeric insulators is tracking of the surface which can directly influence the reliability of the insulator. This paper presents the outcome of an experimental study to determine the conductivity level of the LLDPE-NR compound, filled with different amount of SiO2, TiO2 and MMT nanofiller using Polarization and Depolarization Current (PDC) measurement technique. LLDPE and NR with the ratio composition of 80:20 were selected as a base polymer. Results show that different compositions as well as the surface physical conditions affect the PDC measurement results.

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Spinelli, Giovanni, Patrizia Lamberti, Vincenzo Tucci, Rumiana Kotsilkova, Sonia Tabakova, Radost Ivanova, Polya Angelova et al. « Morphological, Rheological and Electromagnetic Properties of Nanocarbon/Poly(lactic) Acid for 3D Printing : Solution Blending vs. Melt Mixing ». Materials 11, n^o 11 (13 novembre 2018) : 2256. http://dx.doi.org/10.3390/ma11112256.

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The limitation of poor mechanical stability and difficulties in printing electrically conductive components can be overcome owing to the recent introduction of nanotechnology into the field of additive manufacturing (AM) and the consequent development of nonconventional polymer nanocomposites suitable for 3D printing. In the present work, different weight percentages (up to 6 wt % in total) of carbon-based nanostructures—multiwalled carbon nanotubes (MWCNTs), graphene nanoplatelets (GNPs), and a combination of both fillers (MWCNTs/GNPs)—were incorporated into poly(lactic) acid (PLA, Ingeo™) in an attempt to overcome several limitations of conventional 3D manufacturing based on insulating materials. Solution blending and melt mixing were the two fabrication methods adopted for preparation of the samples under test. A comparison of the morphological, rheological, and electrical properties of the resulting nanocomposites was carried out. Moreover, for the same weight concentrations, the influence of physical and geometrical features (i.e., functionalization and aspect ratio) of the embedded fillers was also investigated. Rheological methods were applied to control the quality of fillers dispersion in PLA matrix. The rheological percolation threshold was considered as reference in order to evaluate the internal structure of nanodispersions. TEM visualization, combined with rheological characterizations, was used for efficient control of the nanofiller dispersion. DC characterization revealed that lower electrical percolation thresholds and higher values of electrical conductivity were achieved using fillers with a larger aspect ratio and melt mixing, respectively. Moreover, given the possibility of obtaining complex and appropriate shapes for electromagnetic compatibility (EC) applications, electromagnetic (EM) response of the nanocomposites at the highest filler concentration was investigated in GHz and THz regions. It was found that the electromagnetic shielding efficiency (EMI) of nanocomposites strongly depended on the aspect ratio of the nanofillers, whereas the type of processing technique did not have a significant effect. Therefore, a careful choice of methods and materials must be made to address the final application for which these materials and further 3D printed architectures are designed.

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Demori, Renan, Eveline Bischoff, Ana P. de Azeredo, Susana A. Liberman, Joao Maia et Raquel S. Mauler. « Morphological, thermo-mechanical, and thermal conductivity properties of halloysite nanotube-filled polypropylene nanocomposite foam ». Journal of Cellular Plastics 54, n^o 2 (5 décembre 2016) : 217–33. http://dx.doi.org/10.1177/0021955x16681449.

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Studies about polypropylene nanocomposite foams are receiving attention because nanoparticles can change physical and mechanical properties, as well as improve foaming behavior in terms of homogeneous cell structure, cell density, and void fraction. In this research, the foaming behavior of polypropylene, polypropylene/long-chain branched polypropylene (LCBPP) 100/20 blend, and polypropylene/LCBPP/halloysite nanocomposites with 0.5 and 3 parts per hundred of resin (phr) is studied. The LCBPP was used to improve the rheological properties of polypropylene/LCBPP blend, namely the degree of strain-hardening. Transmission electron microscopy observation indicated that halloysite nanotube particles are well distributed in the matrix by aggregates. Subsequent foaming experiments were conducted using chemical blowing agent in injection-molding processing. Polypropylene foam exhibited high cell density and cell size as well as a collapsing effect, whereas the polypropylene/LCBPP blend showed a reduction of the void fraction and cell density compared to expanded polypropylene. Also, the blend showed reduction of the collapsing effect and increase of homogeneous cell size distribution. The introduction of a small amount of halloysite nanotube in the polypropylene/LCBPP blend improved the foaming behavior of the polypropylene, with a uniform cell structure distribution in the resultant foams. In addition, the cell density of the composite sample was higher than the polypropylene/LCBPP sample, having increased 82% and 136% for 0.5 and 3 phr of loaded halloysite nanotube, respectively. Furthermore, the presence of halloysite nanotube increased crystallization temperature (Tc) and slightly increased dynamic-mechanical properties measured by dynamic-mechanical thermal analysis. By increasing halloysite nanotube content to 3 phr, the insulating effect increased by 13% compared to polypropylene/LCBPP blend. For comparative purposes, the effect on foaming behavior of polypropylene/LCBPP was also investigated using talc microparticles.

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Thabet, Ahmed, Youssef Mobarak, Nourhan Salem et A. M. El-noby. « Performance comparison of selection nanoparticles for insulation of three core belted power cables ». International Journal of Electrical and Computer Engineering (IJECE) 10, n^o 3 (1 juin 2020) : 2779. http://dx.doi.org/10.11591/ijece.v10i3.pp2779-2786.

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This paper presents an investigation on the enhancement of electrical insulations of power cables materials using a new multi-nanoparticles technique. It has been studied the effect of adding specified types and concentrations of nanoparticles to polymeric materials such as PVC for controlling on electric and dielectric performance. Prediction of effective dielectric constant has been done for the new nanocomposites based on Interphase Power Law (IPL) model. The multi-nanoparticles technique has been succeeded for enhancing electric and dielectric performance of power cables insulation compared with adding individual nanoparticles. Finally, it has been investigated on electric field distribution in the new proposed modern insulations for three-phase core belted power cables. This research has focused on studying development of PVC nanocomposite materials performance with electric field distribution superior to the unfilled matrix, and has stressed particularly the effect of filler volume fraction on the electric field distribution.

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Azlan, Nurul Farrahani, Suffiyana Akhbar, Suhaiza Hanim Hanipah et Rahida Wati Sharudin. « A short review on synthesis and characterisation of nano SiO2/TiO2 composite for insulation application ». Malaysian Journal of Chemical Engineering and Technology (MJCET) 4, n^o 2 (31 octobre 2021) : 155. http://dx.doi.org/10.24191/mjcet.v4i2.14972.

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Silica dioxide (SiO2) and titanium dioxide (TiO2) are nanoparticle fillers that are widely incorporated into polymer matrix for thermal insulation application. Combination of both fillers in producing polymer nanocomposite is interesting to review. This paper reviews on the current and recent research on the method to incorporate the SiO2/TiO2 nanoparticles as the fillers into various polymer matrix such as direct mixing, intercalation, sol-gel and in situ polymerisation as well as the effect of nanofillers on the thermal properties, morphology studies, rheology behaviour, mechanical property, and conductivity (thermal and electrical) of the SiO2/TiO2 polymer nanocomposites. This paper also reviews the effect of SiO2/TiO2 nanoparticles to the polymer nanocomposites in term of dielectric properties as a potential electrical insulation material. SiO2 nanoparticles presented to be the best filler to enhance the dielectric properties compared to the TiO2. When both of nanofillers are incorporated into the polymer matrix, a better result in term of mechanical, thermal, and electrical insulation properties are produced.

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Iqbal, Sadia Sagar, Aneela Sabir, Atif Islam, Syed Zain Ul Abdene Bukhari, Muhammad Yasir, M. Arshad Bashir et Ali Bahadur. « Effect of Graphene for Ablation Study of Advanced Composite Materials for Aerospace Applications ». Key Engineering Materials 778 (septembre 2018) : 118–25. http://dx.doi.org/10.4028/www.scientific.net/kem.778.118.

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Graphene was incorporated into elastomeric Matrices using dispersion kneader and two roller mixing mill to fabricate ablative nanocomposites used in hyperthermal environment encountered by space vehicle or rocket motor. The addition of graphene in the host matrix has remarkably reduced the backface temperature elevation during the ablation testing of the ablatives. The linear and mass ablation resistances have been diminished while insulation indexes of the nanocomposites have been increased the graphene incorporation into the elastomeric matrix. Thermal stability and heat absorbance capability of the polymer nanocomposites were progressed with increasing the filler to matrix ratio. Thermal conductivity of the ablatives have been conducted according to the ASTM E1225-99 and D5470-03, respectively to execute the effect of graphene concentration on the thermal transport characteristics of the tested specimens. Tensile strength of the nanocomposite specimen was augmented with increasing graphene to polymer ratio. Scanning electron microscopy was used to scrutinize the evenly dispersed graphene in the polymer matrix, polymer pyrolysis, and voids formation in the ablated nanocomposites.

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Pattanshetti, Virappa Virupaxappa, G. M. Shashidhara et Mysore Guruswamy Veena. « Dielectric and thermal properties of magnesium oxide/poly(aryl ether ketone) nanocomposites ». Science and Engineering of Composite Materials 25, n^o 5 (25 septembre 2018) : 915–25. http://dx.doi.org/10.1515/secm-2016-0273.

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AbstractIn the present study, dielectric and thermal properties of poly(aryl ether ketone) (PAEK)-nanocomposites with varying weight percentage of magnesium oxide (MgO) have been reported. The thermal properties of PAEK/MgO nanocomposites were studied using differential scanning calorimetry, thermogravimetric analysis, thermo-mechanical analysis and thermal conductivity. Transmission electron microscopy of the developed nanocomposites shows agglomerate-free dispersion of MgO nanoparticles in PAEK matrix. From the dielectric properties, dielectric constant of 13 was achieved for 10 wt% PAEK/MgO nanocomposite at 230°C. Further, minimum tan δ and maximum volume resistivity were found for 10 wt% PAEK/MgO nanocomposite. Data from thermal studies indicate that the incorporation of MgO into PAEK significantly enhanced the glass transition temperature and slightly deteriorated the thermal stability, char yield, and flame-retardant properties. Also, highest thermal conductivity and lowest coefficient of thermal expansion were achieved at 10 wt% of the MgO content. An excellent combination of both dielectric and thermal properties of the PAEK/MgO nanocomposites developed in the present study finds its potential application in microelectronics and electrical insulation in power equipments.

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Iqbal, Sadia Sagar, Muhammad Adrees, Adnan Ahmad, Faiza Hassan, Muhammad Yasir, M. Arshad Bashir, Sajid Rasheed Ahmad, Fahd Jamshaid et Waheed Gull Khan. « Tuning of Thermo-Mechanical Performance : Modified Multiwalled Carbon Nanotubes Reinforced SBR/NBR/SR Nanocomposites ». Key Engineering Materials 778 (septembre 2018) : 71–78. http://dx.doi.org/10.4028/www.scientific.net/kem.778.71.

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The present study aimed to identify the potential of modified nanoreinforcement (multiwalled carbon nanotubes; m-MWCNTs) to attenuate the thermal transport/decomposition/transition and mechanical aspects of three different polymeric matrices. In order to develop strong interfacial interaction between the host matrix and the incorporated nanotubes, 3-aminopropyletrimethoxy silane (APTMS) was used to m-MWCNTs. IR spectra confirmed the silane chemical moiety attachment on the upper surface of the MWCNTs. Conventional elastomeric mixing techniques were adopted to disperse m-MWCNTs within the three polymeric matrices (Acrylonitrile butadiene rubber, Silicone rubber, and Styrene Butadiene rubber) separately. SEM images assured the uniform dispersion of m-MWCNTs within the host polymeric matrices. Experimental evaluation of thermal conductivity revealed the reduction of thermal transport through the developed composite specimens by increasing the host polymer matrix to nanofiller concentration (m-MWCNTs). The utmost insulation effect was perceived in the F-MWCNTs incorporated silicone rubber nanocomposite comparatively. Glass transition/crystallization temperatures of the nanocomposites were lessened however melting temperatures were enhanced by impregnating nanotubes into the host polymeric matrices. Maximum thermal stability improvement due to the addition of m-MWCNTs was observed in the silicone elastomeric nanocomposite as compared to the other two systems. Proper dispersion and compatibility of m-MWCNTs with the polymeric matrices effectively enhanced the ultimate tensile strength (UTS)/elongation at break along hardness of rubber of the nanocomposites. The insulation character of m-MWCNTs/silicone rubber system was found best among the explored nanocomposite formulations.

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Yu, Guang, Yujia Cheng et Zhuohua Duan. « Research Progress of Polymers/Inorganic Nanocomposite Electrical Insulating Materials ». Molecules 27, n^o 22 (15 novembre 2022) : 7867. http://dx.doi.org/10.3390/molecules27227867.

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With the rapid development of power, energy, electronic information, rail transit, and aerospace industries, nanocomposite electrical insulating materials have been begun to be widely used as new materials. Polymer/inorganic nanocomposite dielectric materials possess excellent physical and mechanical properties. In addition, numerous unique properties, such as electricity, thermal, sound, light, and magnetic properties are exhibited by these materials. First, the macroscopic quantum tunneling effect, small-size effect, surface effect, and quantum-size effect of nanoparticles are introduced. There are a few anomalous changes in the physical and chemical properties of the matrix, which are caused by these effects. Second, the interaction mechanism between the nanoparticles and polymer matrix is introduced. These include infiltration adsorption theory, chemical bonding, diffusion theory, electrostatic theory, mechanical connection theory, deformation layer theory, and physical adsorption theory. The mechanism of action of the interface on the dielectric properties of the composites is summarized. These are the interface trap effect, interface barrier effect, and homogenization field strength effect. In addition, different interfacial structure models were used to analyze the specific properties of nanocomposite dielectric materials. Finally, the research status of the dielectric properties of nanocomposite dielectric materials in the electrical insulation field is introduced.

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Hsieh, Tsung-Han, Yau-Shian Huang et Ming-Yuan Shen. « Dynamic properties of carbon aerogel/epoxy nanocomposite and carbon fiber-reinforced composite beams ». Journal of Reinforced Plastics and Composites 36, n^o 23 (25 août 2017) : 1745–55. http://dx.doi.org/10.1177/0731684417728585.

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Carbon aerogels are a promising candidate for vibration insulation due to their three-dimensional networked structures interconnected with carbon nanoparticles. However, the effect of adding carbon aerogels to polymer-based composites on their dynamic properties remains unclear. In this study, an epoxy polymer matrix was modified with carbon aerogels, and this modified matrix was used to manufacture nanocomposite plates and carbon fiber-reinforced polymer composite laminates to investigate its dynamic properties. Force vibration tests were performed on cantilever beams of the composite beams. The frequency responses of the composite beams were measured experimentally and analytically; the half-power method was used to calculate the damping ratio for each vibration mode. According to the experimental results, the presence of carbon aerogel in the nanocomposites and laminates steadily increased the natural frequencies. Differences within 10% of the natural frequencies were obtained between the experimental and numerically. Furthermore, the damping ratios of the nanocomposite and laminate beams increased significantly with the increase in aerogel loading. For a nanocomposite with 0.3 wt% aerogel, a damping ratio approximately 44% greater than that of unmodified nanocomposite was obtained. The maximum damping ratio was 4.682% for the laminate with 0.5 wt% aerogel—an 88% increase compared with the unmodified laminate.

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Ghelich, Raziyeh, Rouhollah Mehdinavaz Aghdam et Mohammad Reza Jahannama. « Elevated temperature resistance of SiC-carbon/phenolic nanocomposites reinforced with zirconium diboride nanofibers ». Journal of Composite Materials 52, n^o 9 (14 septembre 2017) : 1239–51. http://dx.doi.org/10.1177/0021998317723447.

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Carbon fiber-reinforced composites with matrices containing ultra-high temperature ceramics show excellent potential as high ablation-resistant materials. In this study, two non-oxide nanostructures, ZrB2 nanofibers and SiC nanoparticles, as reinforcement phases were utilized to develop the carbon/phenolic-ZrB2-SiC (C/Ph-ZS) nanocomposite for the first time. Thermogravimetry analysis illustrated that the residue yield of C/Ph composite at high temperatures was increased by the introduction of above-mentioned nanostructure ceramics. The addition of 7 wt% of ZrB2/SiC nanoadditives homogeneously in a C/Ph composite resulted in an enhancement of the room temperature thermal diffusivity, from 0.00622 to 0.00728 cm2/s. The incorporation of 4–7 wt% of ZrB2/SiC nanofillers in C/Ph composites leads to a reinforced material with about 73% increasing of Shore D hardness. The modified thermal behavior of prepared nanocomposites was examined using oxyacetylene torch at 2500℃ for 160 s. It suggested that the C/Ph-ZS7% nanocomposites with lower density may drastically contribute to meliorate the thermal insulation and ablative properties. The linear ablation rates of C/Ph composites were decreased after adding 7 wt% ZrB2/SiC nanofillers by 18%. The formation of a dense and uniform SiO2 and ZrO2 layer on the ablated surface of C/Ph-ZS nanocomposites could function as an effective oxygen barrier which greatly reduced the ablation rates of the nanocomposites because of the evaporation at elevated temperature, which absorbs heat from the flame and reduces the erosive attack to C/Ph. The ablated C/Ph-ZS nanocomposite with complicated cross-section structure displayed four dense oxidized, porous surface, transient and matrix regions.

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Ogbonna, V. E., A. P. I. Popoola et O. M. Popoola. « Silica nanofillers-reinforced polyimide composites for mechanical, thermal, and electrical insulation applications and recommendations : a review ». Journal of Physics : Conference Series 2368, n^o 1 (1 novembre 2022) : 012001. http://dx.doi.org/10.1088/1742-6596/2368/1/012001.

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Owing to the specific properties of polyimide, its nanocomposites have in recent years shown to be a promising polymer composite for mechanical, thermal, and electrical insulation applications. Studies have in many ways revealed the utilization of the polyimide reinforced nanofillers in the area of insulation practice be it thermal or electrical insulation. However, reinforced polyimide nanocomposites were observed to undergo interfacial bonding issues that have badly influenced their insulation behaviour during service. Dielectric properties and electrical discharge (corona discharge) resistance lifespan of polyimide composites are found degrading during long periods of exposure to elevated temperature conditions. Notwithstanding, efforts have been made on improving the electrical and thermal insulation behaviour of polyimide nanocomposites. As such, the current review study focused on the influence of silica nanoparticles on the thermal, electrical, and mechanical characteristics of polyimide matrix composites for insulation practice and applications. Thus, the vision of the authors is to contribute to the future trend of designing and processing polyimide nanocomposites for insulation applications. Thus, the authors ended the article with furtherance, challenges, and recommendations of further enhancement of polyimide nanocomposites as a candidate material for insulation (electrical and thermal). Hence, the study will pave the way for future studies.

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Fu, Yu-Wei, Yong-Qi Zhang, Wei-Feng Sun et Xuan Wang. « Functionalization of Silica Nanoparticles to Improve Crosslinking Degree, Insulation Performance and Space Charge Characteristics of UV-initiated XLPE ». Molecules 25, n^o 17 (20 août 2020) : 3794. http://dx.doi.org/10.3390/molecules25173794.

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In order to inhibit the outward-migrations of photo-initiator molecules in the ultraviolet-initiated crosslinking process and simultaneously improve the crosslinking degree and dielectric properties of crosslinked polyethylene (XLPE) materials, we have specifically developed surface-modified-SiO2/XLPE nanocomposites with the silica nanofillers that have been functionalized through chemical surface modifications. With the sulfur-containing silanes and 3-mercaptopropyl trimethoxy silane (MPTMS), the functional monomers of auxiliary crosslinker triallyl isocyanurate (TAIC) have been successfully grafted on the silica surface through thiol–ene click chemistry reactions. The grafted functional groups are verified by molecular characterizations of Fourier transform infrared spectra and nuclear magnetic resonance hydrogen spectra. Scanning electronic microscopy (SEM) indicates that the functionalized silica nanoparticles have been filled into polyethylene matrix with remarkably increased dispersivity compared with the neat silica nanoparticles. Under ultraviolet (UV) irradiation, the high efficient crosslinking reactions of polyethylene molecules are facilitated by the auxiliary crosslinkers that have been grafted onto the surfaces of silica nanofillers in polyethylene matrix. With the UV-initiated crosslinking technique, the crosslinking degree, insulation performance, and space charge characteristics of SiO2/XLPE nanocomposites are investigated in comparison with the XLPE material. Due to the combined effects of the high dispersion of nanofillers and the polar-groups of TAIC grafted on the surfaces of SiO2 nanofillers, the functionlized-SiO2/XLPE nanocomposite with an appropriate filling content represents the most preferable crosslinking degree with multiple improvements in the space charge characteristics and direct current dielectric breakdown strength. Simultaneously employing nanodielectric technology and functional-group surface modification, this study promises a modification strategy for developing XLPE nanocomposites with high mechanical and dielectric performances.

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Evtukh, A. A., et O. Bratus. « Electrical Properties of Composite Films with Silicon Nanocrystals in the Insulating Matrix ». Advanced Materials Research 854 (novembre 2013) : 105–10. http://dx.doi.org/10.4028/www.scientific.net/amr.854.105.

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The electrical properties of nanocomposite SiO2(Si) films containing Si nanoclusters have been investigated. The films were formed by oxide assisted growth that included ion plasma sputtering (IPS) of Si target and following high temperature annealing. It was determined that electrical conductivity of the films correspond to the mechanism of hopping conductivity with variable hopping length through the traps near the Fermi level (Mott mechanism) due to the large number of silicon dangling bonds in the dielectric matrix. The peculiarities of charge capture in nanocomposite SiO2(Si) films for their application as the medium for charge storage in memory cells have been investigated by C-V method. The good charge storage possibility of SiO2(Si) films formed by IPS deposition with followed temperature annealing has been observed. The negative differential capacitance has been revealed in conditions of semiconductor surface accumulation. The physical model for explanation of the negative differential capacitance of MIS structures with nanocomposite SiO2(Si) films as the dielectric has been proposed. The model is based on the parallel conjunction of the oxide capacitance and nanocrystals capacitance.

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Zhang, Yong-Qi, Xuan Wang, Ping-Lan Yu et Wei-Feng Sun. « Water-Tree Resistant Characteristics of Crosslinker-Modified-SiO2/XLPE Nanocomposites ». Materials 14, n^o 6 (13 mars 2021) : 1398. http://dx.doi.org/10.3390/ma14061398.

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Trimethylolpropane triacrylate (TMPTA) as a photoactive crosslinker is grafted onto hydrophobic nanosilica surface through click chemical reactions of mercapto double bonds to prepare the functionalized nanoparticles (TMPTA-s-SiO2), which are used to develop TMPTA-s-SiO2/XLPE nanocomposites with improvements in mechanical strength and electrical resistance. The expedited aging experiments of water-tree growth are performed with a water-knife electrode and analyzed in consistence with the mechanical performances evaluated by means of dynamic thermo-mechanical analysis (DMA) and tensile stress–strain characteristics. Due to the dense cross-linking network of polyethylene molecular chains formed on the TMPTA-modified surfaces of SiO2 nanofillers, TMPTA-s-SiO2 nanofillers are chemically introduced into XLPE matrix to acquire higher crosslinking degree and connection strength in the amorphous regions between polyethylene lamellae, accounting for the higher water-tree resistance and ameliorated mechanical performances, compared with pure XLPE and neat-SiO2/XLPE nanocomposite. Hydrophilic TMPTA molecules grafted on the nano-SiO2 surface can inhibit the condensation of water molecules into water micro-beads at insulation defects, thus attenuating the damage of water micro-beads to polyethylene configurations under alternating electric fields and thus restricting water-tree growth in amorphous regions. The intensified interfaces between TMPTA-s-SiO2 nanofillers and XLPE matrix limit the segment motions of polyethylene molecular chains and resist the diffusion of water molecules in XLPE amorphous regions, which further contributes to the excellent water-tree resistance of TMPTA-s-SiO2/XLPE nanocomposites.

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Du, Fei-Peng, Hao Tang et De-Yong Huang. « Thermal Conductivity of Epoxy Resin Reinforced with Magnesium Oxide Coated Multiwalled Carbon Nanotubes ». International Journal of Polymer Science 2013 (2013) : 1–5. http://dx.doi.org/10.1155/2013/541823.

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Magnesium oxide coated multiwalled carbon nanotubes (MgO@MWNT) were fabricated and dispersed into epoxy matrix. The microstructures of MgO@MWNT and epoxy/MgO@MWNT nanocomposites were characterized by TEM and SEM. Electrical resistivity and thermal conductivity of epoxy nanocomposites were investigated with high resistance meter and thermal conductivity meter, respectively. MgO@MWNT has core-shell structure with MgO as shell and nanotube as core, and the thickness of MgO shell is ca. 15 nm. MgO@MWNT has been dispersed well in the epoxy matrix. MgO@MWNT loaded epoxy nanocomposites still retain electrical insulation inspite of the filler content increase. However, thermal conductivity of epoxy was increased with the MgO@MWNT content increasing. When MgO@MWNT content reached 2.0 wt.%, thermal conductivity was increased by 89% compared to neat epoxy, higher than that of unmodified MWNT nanocomposites with the same loading content.

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Ahmad et al., Shanaz. « Acoustic and Thermal Insulation of Nanocomposites for Building Material ». Baghdad Science Journal 17, n^o 2 (11 mai 2020) : 0494. http://dx.doi.org/10.21123/bsj.2020.17.2.0494.

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This work aims to enhance acoustic and thermal insulation properties for polymeric composite by adding nanoclay and rock wool as reinforcement materials with different rations. A polymer blend of (epoxy+ polyester) as matrix materials was used. The Hand lay-up technique was used to manufacture the castings. Epoxy and polyester were mixed at different weight ratios involving (50:50, 60:40, 70:30, 80:20, and 90:10) wt. % of (epoxy: polyester) wt. % respectively. Impact tests for optimum sample (OMR), caustic and thermal insulation tests were performed. Nano clay (Kaolinite) with ratios ( 5 and 7.5% ) wt.% , also hybrid reinforcement materials involving (Kaolite 5 & 7.5 % wt.% + 10% volume fraction of rockwool ) were added as reinforcement materials to the optimum sample. Results of impact test prove that the optimum sample has (80:20) wt. % of mixing ratio of (epoxy: polyester) wt. % for using as matrix materials. Moreover, the adding of nanoclay (Kaolinite) with ratio (7.5 wt.%) leads to the highest sound insulation. The sound intensity started at (99.8) db at 100 Hz, and reached to (101.3) db at 10000 Hz., which is much lower than the values obtained from the un-reinforced blend, of which the sound intensity started at (107.2) db and reached to (108.7) db., at the same range of frequencies. Thermal conductivity results show that the optimum matrix with (7.5 %) wt. % has the lowest value about (0.443 k.w\m .c). The results show that the blend reinforced with nano clay in a weight fraction (7.5)% has the best sound insulation, so that the sound intensity started at (99.8) db at 100 Hz., and reached (101.3) db at 10000 Hz., which is much lower than the values obtained from the unreinforced blend, of which the sound intensity started at (107.2) db and reached (108.7) db., applying the same range of frequencies. The same casting (blend+7.5% nanoclay) showed the lowest value of thermal conductivity (xxxx) W.m°C in comparison with castings that were made of unreinforced blend and those hybridized with rockwool.

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Sun, Wei-Feng, et Peng-Bo Sun. « Electrical Insulation and Radar-Wave Absorption Performances of Nanoferrite/Liquid-Silicone-Rubber Composites ». International Journal of Molecular Sciences 23, n^o 18 (9 septembre 2022) : 10424. http://dx.doi.org/10.3390/ijms231810424.

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Novel radar-wave absorption nanocomposites are developed by filling the nanoscaled ferrites of strontium ferroxide (SrFe12O19) and carbonyl iron (CIP) individually into the highly flexible liquid silicone rubber (LSR) considered as dielectric matrix. Nanofiller dispersivities in SrFe12O19/LSR and CIP/LSR nanocomposites are characterized by scanning electronic microscopy, and the mechanical properties, electric conductivity, and DC dielectric-breakdown strength are tested to evaluate electrical insulation performances. Radar-wave absorption performances of SrFe12O19/LSR and CIP/LSR nanocomposites are investigated by measuring electromagnetic response characteristics and radar-wave reflectivity, indicating the high radar-wave absorption is dominantly derived from magnetic losses. Compared with pure LSR, the SrFe12O19/LSR and CIP/LSR nanocomposites represent acceptable reductions in mechanical tensile and dielectric-breakdown strengths, while rendering a substantial nonlinearity of electric conductivity under high electric fields. SrFe12O19/LSR nanocomposites provide high radar-wave absorption in the frequency band of 11~18 GHz, achieving a minimum reflection loss of −33 dB at 11 GHz with an effective absorption bandwidth of 10 GHz. In comparison, CIP/LSR nanocomposites realize a minimum reflection loss of −22 dB at 7 GHz and a remarkably larger effective absorption bandwidth of 3.9 GHz in the lower frequency range of 2~8 GHz. Radar-wave transmissions through SrFe12O19/LSR and CIP/LSR nanocomposites in single- and double-layered structures are analyzed with CST electromagnetic-field simulation software to calculate radar reflectivity for various absorbing-layer thicknesses. Dual-layer absorbing structures are modeled by specifying SrFe12O19/LSR and CIP/LSR nanocomposites, respectively, as match and loss layers, which are predicted to acquire a significant improvement in radar-wave absorption when the thicknesses of match and loss layers approach 1.75 mm and 0.25 mm, respectively.

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Zazoum, B., E. David et A. D. Ngô. « Correlation between Structure and Dielectric Breakdown in LDPE/HDPE/Clay Nanocomposites ». ISRN Nanomaterials 2014 (19 mars 2014) : 1–9. http://dx.doi.org/10.1155/2014/612154.

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Cross-linked polyethylene (XLPE) is commonly used in medium/high voltage insulation due to its excellent dielectric properties and acceptable thermomechanical properties. To improve both electrical and thermal properties to a point that would possibly avoid the need for crosslinking, nanoclay fillers can be added to polymer matrix to form nanocomposites materials. In this paper, PE/clay nanocomposites were processed by mixing a commercially available premixed polyethylene/O-MMT masterbatch into a polyethylene blend matrix containing 80 wt% low density polyethylene LDPE and 20 wt% high density polyethylene HDPE with and without compatibilizer using a corotating twin-screw extruder. Various characterization techniques were employed in this paper, including optical microscopy, AFM, TEM, TGA, DMTA, and dielectric breakdown measurements in order to understand the correlation between structure and short-term dielectric breakdown strength.

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Choi, Won-Jong, Seul-Yi Lee et Soo-Jin Park. « Effect of Ambient Plasma Treatments on Thermal Conductivity and Fracture Toughness of Boron Nitride Nanosheets/Epoxy Nanocomposites ». Nanomaterials 13, n^o 1 (27 décembre 2022) : 138. http://dx.doi.org/10.3390/nano13010138.

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With the rapid growth in the miniaturization and integration of modern electronics, the dissipation of heat that would otherwise degrade the device efficiency and lifetime is a continuing challenge. In this respect, boron nitride nanosheets (BNNS) are of significant attraction as fillers for high thermal conductivity nanocomposites due to their high thermal stability, electrical insulation, and relatively high coefficient of thermal conductivity. Herein, the ambient plasma treatment of BNNS (PBNNS) for various treatment times is described for use as a reinforcement in epoxy nanocomposites. The PBNNS-loaded epoxy nanocomposites are successfully manufactured in order to investigate the thermal conductivity and fracture toughness. The results indicate that the PBNNS/epoxy nanocomposites subjected to 7 min plasma treatment exhibit the highest thermal conductivity and fracture toughness, with enhancements of 44 and 110%, respectively, compared to the neat nanocomposites. With these enhancements, the increases in surface free energy and wettability of the PBNNS/epoxy nanocomposites are shown to be attributable to the enhanced interfacial adhesion between the filler and matrix. It is demonstrated that the ambient plasma treatments enable the development of highly dispersed conductive networks in the PBNNS epoxy system.

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Kim, Eunk Young, Seung Yong Jeong, Gyo Jic Shin, Sang Kug Lee et Kyung Ho Choi. « Properties of Thermal Conductivity on Polyimide/Clay Nanocomposite Foams ». Applied Mechanics and Materials 229-231 (novembre 2012) : 215–18. http://dx.doi.org/10.4028/www.scientific.net/amm.229-231.215.

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We synthesized polyimide (based on ODA-PMDA) and polyimide foam and polyimide/clay foam that pore size was uniform about 1㎛. We identified that the clay layers are well dispersed in polyimide matrix and achieved exfoliation structure by X-ray diffraction. And we compared thermal conductivity of PI, PI foam, PI/clay foam. Thermal conductivity decreased up to maximum 28 % by introducing both pores and clay layers. Exfoliated structure of clay leads to decrease of thermal conductivity by thermal barrier effect. Also, the presence of clay could considerably reinforce the poor mechanical properties of polyimide by foam because of interfacial interaction between clay layers and polymer matrix. Through the this results, it has shown that this study may provide an effective method to prepare polymer/clay nanocomposite foams having exfoliation structure, and can be used as insulating material having low thermal conductivity.

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