Artigos de revistas: "Electrically conductive thermoplastic composites"

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Kim, Namsoo Peter. "3D-Printed Conductive Carbon-Infused Thermoplastic Polyurethane". Polymers 12, n.º 6 (27 de maio de 2020): 1224. http://dx.doi.org/10.3390/polym12061224.

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3D printable, flexible, and conductive composites are prepared by incorporating a thermoplastic elastomer and electrically conductive carbon fillers. The advantageous printability, workability, chemical resistance, electrical conductivity, and biocompatibility components allowed for an enabling of 3D-printed electronics, electromagnetic interference (EMI) shielding, static elimination, and biomedical sensors. Carbon-infused thermoplastic polyurethane (C/TPU) composites have been demonstrated to possess right-strained sensing abilities and are the candidate in fields such as smart textiles and biomedical sensing. Flexible and conductive composites were prepared by a mechanical blending of biocompatible TPU and carbons. 3D structures that exhibit mechanical flexibility and electric conductivity were successfully printed. Three different types of C/TPU composites, carbon nanotube (CNT), carbon black (CCB), and graphite (G) were prepared with differentiating sizes and composition of filaments. The conductivity of TPU/CNT and TPU/CCB composite filaments increased rapidly when the loading amount of carbon fillers exceeded the filtration threshold of 8%–10% weight. Biocompatible G did not form a conductive pathway in the TPU; resistance to indentation deformation of the TPU matrix was maintained by weight by 40%. Adding a carbon material to the TPU improved the mechanical properties of the composites, and carbon fillers could improve electrical conductivity without losing biocompatibility. For the practical use of the manufactured filaments, optimal printing parameters were determined, and an FDM printing condition was adjusted. Through this process, a variety of soft 3D-printed C/TPU structures exhibiting flexible and robust features were built and tested to investigate the performance of the possible application of 3D-printed electronics and medical scaffolds.

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Akonda, Mahmudul H., Carl A. Lawrence e Hassan M. EL-Dessouky. "Electrically conductive recycled carbon fibre-reinforced thermoplastic composites". Journal of Thermoplastic Composite Materials 28, n.º 11 (21 de novembro de 2013): 1550–63. http://dx.doi.org/10.1177/0892705713513294.

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Probst, Henriette, Konrad Katzer, Andreas Nocke, Rico Hickmann, Martina Zimmermann e Chokri Cherif. "Melt Spinning of Highly Stretchable, Electrically Conductive Filament Yarns". Polymers 13, n.º 4 (16 de fevereiro de 2021): 590. http://dx.doi.org/10.3390/polym13040590.

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Electrically conductive fibers are required for various applications in modern textile technology, e.g., the manufacturing of smart textiles and fiber composite systems with textile-based sensor and actuator systems. According to the state of the art, fine copper wires, carbon rovings, or metallized filament yarns, which offer very good electrical conductivity but low mechanical elongation capabilities, are primarily used for this purpose. However, for applications requiring highly flexible textile structures, as, for example, in the case of wearable smart textiles and fiber elastomer composites, the development of electrically conductive, elastic yarns is of great importance. Therefore, highly stretchable thermoplastic polyurethane (TPU) was compounded with electrically conductive carbon nanotubes (CNTs) and subsequently melt spun. The melt spinning technology had to be modified for the processing of highly viscous TPU–CNT compounds with fill levels of up to 6 wt.% CNT. The optimal configuration was achieved at a CNT content of 5 wt.%, providing an electrical resistance of 110 Ωcm and an elongation at break of 400%.

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Grellmann, Henriette, Mathis Bruns, Felix Michael Lohse, Iris Kruppke, Andreas Nocke e Chokri Cherif. "Development of an Elastic, Electrically Conductive Coating for TPU Filaments". Materials 14, n.º 23 (24 de novembro de 2021): 7158. http://dx.doi.org/10.3390/ma14237158.

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Electrically conductive filaments are used in a wide variety of applications, for example, in smart textiles and soft robotics. Filaments that conduct electricity are required for the transmission of energy and information, but up until now, most electrically conductive fibers, filaments and wires offer low mechanical elongation. Therefore, they are not well suited for the implementation into elastomeric composites and textiles that are worn close to the human body and have to follow a wide range of movements. In order to overcome this issue, the presented study aims at the development of electrically conductive and elastic filaments based on a coating process suited for multifilament yarns made of thermoplastic polyurethane (TPU). The coating solution contains TPU, carbon nanotubes (CNT) and N-Methyl-2-pyrrolidone (NMP) with varied concentrations of solids and electrically conductive particles. After applying the coating to TPU multifilament yarns, the mechanical and electrical properties are analyzed. A special focus is given to the electromechanical behavior of the coated yarns under mechanical strain loading. It is determined that the electrical conductivity is maintained even at elongations of up to 100%.

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Araya-Hermosilla, Esteban, Alice Giannetti, Guilherme Macedo R. Lima, Felipe Orozco, Francesco Picchioni, Virgilio Mattoli, Ranjita K. Bose e Andrea Pucci. "Thermally Switchable Electrically Conductive Thermoset rGO/PK Self-Healing Composites". Polymers 13, n.º 3 (21 de janeiro de 2021): 339. http://dx.doi.org/10.3390/polym13030339.

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Among smart materials, self-healing is one of the most studied properties. A self-healing polymer can repair the cracks that occurred in the structure of the material. Polyketones, which are high-performance thermoplastic polymers, are a suitable material for a self-healing mechanism: a furanic pendant moiety can be introduced into the backbone and used as a diene for a temperature reversible Diels-Alder reaction with bismaleimide. The Diels-Alder adduct is formed at around 50 °C and broken at about 120 °C, giving an intrinsic, stimuli-responsive self-healing material triggered by temperature variations. Also, reduced graphene oxide (rGO) is added to the polymer matrix (1.6–7 wt%), giving a reversible OFF-ON electrically conductive polymer network. Remarkably, the electrical conductivity is activated when reaching temperatures higher than 100 °C, thus suggesting applications as electronic switches based on self-healing soft devices.

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Cabrera, Eusebio Duarte, Seunghyun Ko, Xilian Ouyang, Elliott Straus, L. James Lee e Jose M. Castro. "Technical feasibility of a new approach to electromagnetic interference (EMI) shielding of injection molded parts using in-mold coated (IMC) nanopaper". Journal of Polymer Engineering 34, n.º 8 (1 de outubro de 2014): 739–46. http://dx.doi.org/10.1515/polyeng-2014-0053.

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Abstract Electromagnetic interference (EMI) is a disturbance that affects an electrical circuit due to electromagnetic radiation emitted from an external source. EMI may induce malfunction of equipment, interference with telecommunications and degradation up to total loss of data. EMI shielding refers to the reflection and/or adsorption of electromagnetic radiation by a highly electrically conductive material, usually metal, or polymer composites filled with conductive fillers. However, metal coatings tend to corrode and acceptable EMI shielding levels are difficult to achieve using conductive fillers in a thermoplastic matrix. This study presents a new approach to EMI shielding of plastic parts using in-mold coated (IMC) nanoparticle thin films or nanopapers to create a highly conductive top layer. EMI shielding effectiveness (SE) and electrical conductivity were measured.

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Aloqalaa, Ziyad. "Electrically Conductive Fused Deposition Modeling Filaments: Current Status and Medical Applications". Crystals 12, n.º 8 (28 de julho de 2022): 1055. http://dx.doi.org/10.3390/cryst12081055.

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Fused Deposition Modeling (FDM) is one of the most popular three dimensional (3D) printing techniques especially among researchers. Recently, FDM has been widely developed and improved in many areas. One of these improvements is the introduction of electrically conductive filaments. In general, conductive filaments are usually made of conductive polymer composites. These composites consist of a thermoplastic material blended with carbon-based materials. The quantity of commercially available conductive filaments has grown significantly in recent years. This paper presents a sample of currently available conductive filaments (eight filaments were chosen). These samples were compared by measuring resistance value and highlighting resulted defects of each sample. Additionally, this paper searched and reviewed articles that used conductive FDM filaments in medical applications. These articles were collected and summarized in terms of name of filaments were used, the specific function of the printed conductive object, and name of the printer used to print the conductive object. In conclusion, the main purpose of this project is to facilitate the work of future medical researchers who would like to use commercially available conductive FDM filaments.

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Gul, Jahan Zeb, Memoon Sajid e Kyung Hyun Choi. "Retracted Article: 3D printed highly flexible strain sensor based on TPU–graphene composite for feedback from high speed robotic applications". Journal of Materials Chemistry C 7, n.º 16 (2019): 4692–701. http://dx.doi.org/10.1039/c8tc03423k.

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A novel, highly flexible and electrically resistive-type strain sensor with a special three-dimensional conductive network was 3D printed using a composite of conductive graphene pellets and flexible thermoplastic polyurethane (TPU) pellets.

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Kaynan, Ozge, Alptekin Yıldız, Yunus Emre Bozkurt, Elif Ozden Yenigun e Hulya Cebeci. "Electrically conductive high-performance thermoplastic filaments for fused filament fabrication". Composite Structures 237 (abril de 2020): 111930. http://dx.doi.org/10.1016/j.compstruct.2020.111930.

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Dils, Werft, Walter, Zwanzig, von Krshiwoblozki e Schneider-Ramelow. "Investigation of the Mechanical and Electrical Properties of Elastic Textile/Polymer Composites for Stretchable Electronics at Quasi-Static or Cyclic Mechanical Loads". Materials 12, n.º 21 (1 de novembro de 2019): 3599. http://dx.doi.org/10.3390/ma12213599.

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In the last decade, interest in stretchable electronic systems that can be bent or shaped three-dimensionally has increased. The application of these systems is that they differentiate between two states and derive there from the requirements for the materials used: once formed, but static or permanently flexible. For this purpose, new materials that exceed the limited mechanical properties of thin metal layers as the typical printed circuit board conductor materials have recently gained the interest of research. In this work, novel electrically conductive textiles were used as conductor materials for stretchable circuit boards. Three different fabrics (woven, knitted and nonwoven) made of silver-plated polyamide fibers were investigated for their mechanical and electrical behavior under quasi-static and cyclic mechanical loads with simultaneous monitoring of the electrical resistance. Thereto, the electrically conductive textiles were embedded into a thermoplastic polyurethane dielectric matrix and structured by laser cutting into stretchable conductors. Based on the characterization of the mechanical and electrical material behavior, a life expectancy was derived. The results are compared with previously investigated stretchable circuit boards based on thermoplastic elastomer and meander-shaped conductor tracks made of copper foils. The microstructural changes in the material caused by the applied mechanical loads were analyzed and are discussed in detail to provide a deep understanding of failure mechanisms.

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Karahan Toprakçı, Hatice Aylin, Mukaddes Şeval Çetin e Ozan Toprakçı. "Fabrication of Conductive Polymer Composites from Turkish Hemp-Derived Carbon Fibers and Thermoplastic Elastomers". Tekstil ve Mühendis 28, n.º 121 (31 de março de 2021): 32–38. http://dx.doi.org/10.7216/1300759920212812104.

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In this study, carbon fibers filled flexible conductive polymer composites were fabricated. Turkish hemp was used to produce conductive carbon fibers. In order to do this, hemp fibers were carbonized under different conditions. After this step, flexible conductive composites were fabricated by using poly[styrene-b-(ethylene-co-butylene)-b-styrene] matrix and hemp-based carbon fibers. Composite films were produced by combination of solvent casting and hot pressing. Various levels of carbon fibers were used in order to determine the percolation behavior of the composites. Morphological and electrical properties of the composite films were analyzed. Electrical resistivity of the samples decreased by increasing the filler ratio.

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Bagatella, Simone, Annacarla Cereti, Francesco Manarini, Marco Cavallaro, Raffaella Suriano e Marinella Levi. "Thermally Conductive and Electrically Insulating Polymer-Based Composites Heat Sinks Fabricated by Fusion Deposition Modeling". Polymers 16, n.º 3 (4 de fevereiro de 2024): 432. http://dx.doi.org/10.3390/polym16030432.

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This study explores the potential of novel boron nitride (BN) microplatelet composites with combined thermal conduction and electrical insulation properties. These composites are manufactured through Fusion Deposition Modeling (FDM), and their application for thermal management in electronic devices is demonstrated. The primary focus of this work is, therefore, the investigation of the thermoplastic composite properties to show the 3D printing of lightweight polymeric heat sinks with remarkable thermal performance. By comparing various microfillers, including BN and MgO particles, their effects on material properties and alignment within the polymer matrix during filament fabrication and FDM processing are analyzed. The characterization includes the evaluation of morphology, thermal conductivity, and mechanical and electrical properties. Particularly, a composite with 32 wt% of BN microplatelets shows an in-plane thermal conductivity of 1.97 W m−1 K−1, offering electrical insulation and excellent printability. To assess practical applications, lightweight pin fin heat sinks using these composites are designed and 3D printed. Their thermal performance is evaluated via thermography under different heating conditions. The findings are very promising for an efficient and cost-effective fabrication of thermal devices, which can be obtained through extrusion-based Additive Manufacturing (AM), such as FDM, and exploited as enhanced thermal management solutions in electronic devices.

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Carneiro, OS, JA Covas, R. Reis, B. Brulé e JJ Flat. "The effect of processing conditions on the characteristics of electrically conductive thermoplastic composites". Journal of Thermoplastic Composite Materials 25, n.º 5 (26 de agosto de 2011): 607–29. http://dx.doi.org/10.1177/0892705711417032.

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Volponi, Ruggero, Felice De Nicola e 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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Kypta, Chadwick J., Brian A. Young, Anthony Santamaria e Adam S. Hollinger. "Multiwalled Carbon Nanotube-Filled Polymer Composites for Direct Injection Molding of Bipolar Plates". ECS Meeting Abstracts MA2022-02, n.º 40 (9 de outubro de 2022): 1457. http://dx.doi.org/10.1149/ma2022-02401457mtgabs.

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Fuel cell bipolar plates are commonly fabricated from graphite and stainless steel, however machining intricate channels into these materials can be a costly and time-consuming process. For this reason, we are exploring injection molding of polymer composite bipolar plates. Polymer composites offer the potential for lightweight, low-cost plates [1]. Several factors impact the ability of a polymer composite to conduct electricity. The geometry, filler weight percentage, dispersion, and the physical properties of the fillers are important in forming an electrical pathway through the composite. In this study, polymer composites based on nylon were injection molded with different weight percentages of conductive filler. Initially, carbon fiber was added to nylon at weight percentages ranging from 10 to 50%. Results show that the percolation threshold for carbon fiber in nylon occurs around 25 wt%. While carbon fiber loadings beyond 50 wt% would further increase conductivity, the increased viscosity of the polymer blends can inhibit proper injection molding. Multiwalled carbon nanotubes were then added to the direct injection-molded nylon/carbon fiber composites to investigate the synergistic effects of multiple conductive fillers [2]. By introducing carbon nanotubes into the polymer matrix, the nanotubes act as a bridge between the carbon fibers. SEM images show that the MWCNTs fill the void between each fiber due to their smaller size and their ease of dispersion. This bridging creates more conductive pathways within the composite, thereby increasing the electrical conductivity. Samples with MWCNTs reached conductivities nearing the United States Department of Energy technical target for bipolar plate conductivity (> 100 S/cm). Mighri, F.; Huneault, M. A.; Champagne, M. F., Electrically conductive thermoplastic blends for injection and compression molding of bipolar plates in the fuel cell application. Polymer Engineering and Science 2004, 44 (9), 1755-1765. Zameroski, R.; Kypta, C. J.; Young, B. A.; Sanei, S. H. R.; Hollinger, A. S., Mechanical and Electrical Properties of Injection-Molded MWCNT-Reinforced Polyamide 66 Hybrid Composites. Journal of Composites Science 2020, 4 (4), 14. Figure 1

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Tariq, Muhammad, Utkarsh, Nabeel Ahmed Syed, Amir Hossein Behravesh, Remon Pop-Iliev e Ghaus Rizvi. "Optimization of Filler Compositions of Electrically Conductive Polypropylene Composites for the Manufacturing of Bipolar Plates". Polymers 15, n.º 14 (18 de julho de 2023): 3076. http://dx.doi.org/10.3390/polym15143076.

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In this research, polypropylene (PP)–graphite composites were prepared using the melt mixing technique in a twin-screw extruder. Graphite, multi-walled carbon nanotubes (MWCNT), carbon black (CB), and expanded graphite (EG) were added to the PP in binary, ternary, and quaternary formations. The graphite was used as a primary filler, and MWCNT, CB, and EG were added to the PP–graphite composites as secondary fillers at different compositions. The secondary filler compositions were considered the control input factors of the optimization study. A full factorial design of the L-27 Orthogonal Array (OA) was used as a Design of Experiment (DOE). The through-plane electrical conductivity and flexural strength were considered the output responses. The experimental data were interpreted via Analysis of Variance (ANOVA) to evaluate the significance of each secondary filler. Furthermore, statistical modeling was performed using response surface methodology (RSM) to predict the properties of the composites as a function of filler composition. The empirical model for the filler formulation demonstrated an average accuracy of 83.9% and 93.4% for predicting the values of electrical conductivity and flexural strength, respectively. This comprehensive experimental study offers potential guidelines for producing electrically conductive thermoplastic composites for the manufacturing of bipolar fuel cell plates.

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Probst, Henriette, Joanna Wollmann, Johannes Mersch, Andreas Nocke e Chokri Cherif. "Melt Spinning of Elastic and Electrically Conductive Filament Yarns and their Usage as Strain Sensors". Solid State Phenomena 333 (10 de junho de 2022): 81–89. http://dx.doi.org/10.4028/p-naou93.

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Electrically conductive fibers are required for numerous fields of application in modern textile technology. They are of particular importance in the manufacturing of smart textiles and fiber composite systems with textile-based sensor and actuator systems. Elastic and electrically conductive filaments can be used as strain sensors for monitoring the mechanical loading of critical components. In order to produce such sensorial filaments, thermoplastic polyurethane (TPU) is compounded with carbon nanotubes (CNT) and melt spun. The mechanical performances of filaments produced at different spinning speeds and containing different amounts of CNT were tested. Furthermore, the correlation between the specific electrical resistance of the filaments and the mechanical strain were analyzed depending on the CNT-content and the spinning speed.

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Finegan, Ioana C., e Gary G. Tibbetts. "Electrical conductivity of vapor-grown carbon fiber/thermoplastic composites". Journal of Materials Research 16, n.º 6 (junho de 2001): 1668–74. http://dx.doi.org/10.1557/jmr.2001.0231.

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Conducting polymers are required for applications such as radio frequency interference shielding, primerless electrostatic painting, and static discharge. We have used vapor-grown carbon fiber (VGCF) as an additive to investigate conducting thermoplastics for these applications. The electrical properties of VGCF/polypropylene (PP) and VGCF/nylon composites are very attractive compared with those provided by other conventional conducting additives. Because of the low diameter of the VGCF used, the onset of conductivity (percolation threshold) can be below 3 vol%. Because of the highly conductive nature of the fibers, particularly after a graphitization step, the composites can reach resistivities as low as 0.15 Ω cm.

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Regnier, Julie, Aurélie Cayla, Christine Campagne e Éric Devaux. "Melt Spinning of Flexible and Conductive Immiscible Thermoplastic/Elastomer Monofilament for Water Detection". Nanomaterials 12, n.º 1 (29 de dezembro de 2021): 92. http://dx.doi.org/10.3390/nano12010092.

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In many textile fields, such as industrial structures or clothes, one way to detect a specific liquid leak is the electrical conductivity variation of a yarn. This yarn can be developed using melt spun of Conductive Polymer Composites (CPCs), which blend insulating polymer and electrically conductive fillers. This study examines the influence of the proportions of an immiscible thermoplastic/elastomer blend for its implementation and its water detection. The thermoplastic polymer used for the detection property is the polyamide 6.6 (PA6.6) filled with enough carbon nanotubes (CNT) to exceed the percolation threshold. However, the addition of fillers decreases the polymer fluidity, resulting in the difficulty to implement the CPC. Using an immiscible polymers blend with an elastomer, which is a propylene-based elastomer (PBE) permits to increase this fluidity and to create a flexible conductive monofilament. After characterizations (morphology, rheological and mechanical) of this blend (PA6.6CNT/PBE) in different proportions, two principles of water detection are established and carried out with the monofilaments: the principle of absorption and the short circuit. It is found that the morphology of the immiscible polymer blend had a significant role in the water detection.

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Gorshenev, V. N. "Influence of Technological Conditions in the Formation of Electrically Conductive Thermoplastic Polymer-Graphite Composites". Inorganic Materials: Applied Research 13, n.º 2 (abril de 2022): 515–22. http://dx.doi.org/10.1134/s2075113322020149.

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Abyzova, Elena, Ilya Petrov, Ilya Bril’, Dmitry Cheshev, Alexey Ivanov, Maxim Khomenko, Andrey Averkiev et al. "Universal Approach to Integrating Reduced Graphene Oxide into Polymer Electronics". Polymers 15, n.º 24 (5 de dezembro de 2023): 4622. http://dx.doi.org/10.3390/polym15244622.

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Flexible electronics have sparked significant interest in the development of electrically conductive polymer-based composite materials. While efforts are being made to fabricate these composites through laser integration techniques, a versatile methodology applicable to a broad range of thermoplastic polymers remains elusive. Moreover, the underlying mechanisms driving the formation of such composites are not thoroughly understood. Addressing this knowledge gap, our research focuses on the core processes determining the integration of reduced graphene oxide (rGO) with polymers to engineer coatings that are not only flexible and robust but also exhibit electrical conductivity. Notably, we have identified a particular range of laser power densities (between 0.8 and 1.83 kW/cm2), which enables obtaining graphene polymer composite coatings for a large set of thermoplastic polymers. These laser parameters are primarily defined by the thermal properties of the polymers as confirmed by thermal analysis as well as numerical simulations. Scanning electron microscopy with elemental analysis and X-ray photoelectron spectroscopy showed that conductivity can be achieved by two mechanisms—rGO integration and polymer carbonization. Additionally, high-speed videos allowed us to capture the graphene oxide (GO) modification and melt pool formation during laser processing. The cross-sectional analysis of the laser-processed samples showed that the convective flows are present in the polymer substrate explaining the observed behavior. Moreover, the practical application of our research is exemplified through the successful assembly of a conductive wristband for wearable devices. Our study not only fills a critical knowledge gap but also offers a tangible illustration of the potential impact of laser-induced rGO-polymer integration in materials science and engineering applications.

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Kazemi, Yasamin, Adel Ramezani Kakroodi, Amir Ameli, Tobin Filleter e Chul B. Park. "Highly stretchable conductive thermoplastic vulcanizate/carbon nanotube nanocomposites with segregated structure, low percolation threshold and improved cyclic electromechanical performance". Journal of Materials Chemistry C 6, n.º 2 (2018): 350–59. http://dx.doi.org/10.1039/c7tc04501h.

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Xu, Ying-Te, Yan Wang, Chang-Ge Zhou, Wen-Jin Sun, Kun Dai, Jian-Hua Tang, Jun Lei, Ding-Xiang Yan e Zhong-Ming Li. "An electrically conductive polymer composite with a co-continuous segregated structure for enhanced mechanical performance". Journal of Materials Chemistry C 8, n.º 33 (2020): 11546–54. http://dx.doi.org/10.1039/d0tc02265a.

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Carbon nanotube (CNT)/thermoplastic polyurethane (TPU) composite containing a novel co-continuous segregated structure was developed. And the electrical conductivity and mechanical performance were simultaneously improved.

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Wu, Haoyi, Sum Wai Chiang, Cheng Yang, Ziyin Lin, Jingping Liu, Kyoung-Sik Moon, Feiyu Kang, Bo Li e Ching Ping Wong. "Conformal Pad-Printing Electrically Conductive Composites onto Thermoplastic Hemispheres: Toward Sustainable Fabrication of 3-Cents Volumetric Electrically Small Antennas". PLOS ONE 10, n.º 8 (28 de agosto de 2015): e0136939. http://dx.doi.org/10.1371/journal.pone.0136939.

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Latko-Durałek, Paulina, Rafał Kozera, Jan Macutkevič, Kamil Dydek e Anna Boczkowska. "Relationship between Viscosity, Microstructure and Electrical Conductivity in Copolyamide Hot Melt Adhesives Containing Carbon Nanotubes". Materials 13, n.º 20 (9 de outubro de 2020): 4469. http://dx.doi.org/10.3390/ma13204469.

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The polymeric adhesive used for the bonding of thermoplastic and thermoset composites forms an insulating layer which causes a real problem for lightning strike protection. In order to make that interlayer electrically conductive, we studied a new group of electrically conductive adhesives based on hot melt copolyamides and multi-walled carbon nanotubes fabricated by the extrusion method. The purpose of this work was to test four types of hot melts to determine the effect of their viscosity on the dispersion of 7 wt % multi-walled carbon nanotubes and electrical conductivity. It was found that the dispersion of multi-walled carbon nanotubes, understood as the amount of the agglomerates in the copolyamide matrix, is not dependent on the level of the viscosity of the polymer. However, the electrical conductivity, analyzed by four-probe method and dielectric spectroscopy, increases when the number of carbon nanotube agglomerates decreases, with the highest value achieved being 0.67 S/m. The inclusion of 7 wt % multi-walled carbon nanotubes into each copolyamide improved their thermal stability and changed their melting points by only a few degrees. The addition of carbon nanotubes makes the adhesive’s surface more hydrophilic or hydrophobic depending on the type of copolyamide used.

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Lepak-Kuc, Sandra, Bartłomiej Podsiadły, Andrzej Skalski, Daniel Janczak, Małgorzata Jakubowska e Agnieszka Lekawa-Raus. "Highly Conductive Carbon Nanotube-Thermoplastic Polyurethane Nanocomposite for Smart Clothing Applications and Beyond". Nanomaterials 9, n.º 9 (9 de setembro de 2019): 1287. http://dx.doi.org/10.3390/nano9091287.

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The following paper presents a simple, inexpensive and scalable method of production of carbon nanotube-polyurethane elastomer composite. The new method enables the formation of fibers with 40% w/w of nanotubes in a polymer. Thanks to the 8 times higher content of nanotubes than previously reported for such composites, over an order of magnitude higher electrical conductivity is also observed. The composite fibers are highly elastic and both their electrical and mechanical properties may be easily controlled by changing the nanotubes content in the composite. It is shown that these composite fibers may be easily integrated with traditional textiles by sewing or ironing. However, taking into account their light-weight, high conductivity, flexibility and easiness of molding it may be expected that their potential applications are not limited to the smart textiles industry.

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Rich, Steven I., Vasudevan Nambeesan, Rehan Khan e Carmel Majidi. "Tuning the composition of conductive thermoplastics for stiffness switching and electrically activated healing". Journal of Intelligent Material Systems and Structures 30, n.º 18-19 (22 de setembro de 2019): 2908–18. http://dx.doi.org/10.1177/1045389x19873411.

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We introduce a class of stiffness-tuning polymer composites and carefully examine the influence of electrical activation and temperature on stiffness for a wide range of use cases. The composites are composed of a polycaprolactone matrix embedded with a percolating network of acetylene carbon black or multi-walled carbon nanotubes. This work builds on previous efforts with thermally activated stiffness-switching composites, which can enable reliable, high-switching-ratio stiffness-switching devices that are stiff in the passive state and are not confined to specific geometries or layouts. Here, we systematically investigate the effects of filler type, filler concentration, and matrix polymer molecular weight on the critical properties of the stiffness-switching material. Using these parameters, we develop a composition selection guide, which we use to construct three different stiffness-switching applications: a highly extensible stiffness-switching tendon, a large area moldable sheet, and an electrically healable mechanical fuse.

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Alves, Carine, Janete Oliveira, Alberto Tannus, Alessandra Tarpani e José Tarpani. "Detection and Imaging of Damages and Defects in Fibre-Reinforced Composites by Magnetic Resonance Technique". Materials 14, n.º 4 (19 de fevereiro de 2021): 977. http://dx.doi.org/10.3390/ma14040977.

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Defectively manufactured and deliberately damaged composite laminates fabricated with different continuous reinforcing fibres (respectively, carbon and glass) and polymer matrices (respectively, thermoset and thermoplastic) were inspected in magnetic resonance imaging equipment. Two pulse sequences were evaluated during non-destructive examination conducted in saline solution-immersed samples to simulate load-bearing orthopaedic implants permanently in contact with biofluids. The orientation, positioning, shape, and especially the size of translaminar and delamination fractures were determined according to stringent structural assessment criteria. The spatial distribution, shape, and contours of water-filled voids were sufficiently delineated to infer the amount of absorbed water if thinner image slices than this study were used. The surface texture of composite specimens featuring roughness, waviness, indentation, crushing, and scratches was outlined, with fortuitous artefacts not impairing the image quality and interpretation. Low electromagnetic shielding glass fibres delivered the highest, while electrically conductive carbon fibres produced the poorest quality images, particularly when blended with thermoplastic polymer, though reliable image interpretation was still attainable.

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Latko-Durałek, Paulina, Michał Misiak e Anna Boczkowska. "Electrically Conductive Adhesive Based on Thermoplastic Hot Melt Copolyamide and Multi-Walled Carbon Nanotubes". Polymers 14, n.º 20 (17 de outubro de 2022): 4371. http://dx.doi.org/10.3390/polym14204371.

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For the bonding of the lightweight composite parts, it is desired to apply electrically conductive adhesive to maintain the ability to shield electromagnetic interference. Among various solvent-based adhesives, there is a new group of thermoplastic hot melt adhesives that are easy to use, solidify quickly, and are environment-friendly. To make them electrically conductive, a copolyamide-based hot melt adhesive was mixed with 5 and 10 wt% of carbon nanotubes using a melt-blending process. Well-dispersed nanotubes, observed by a high-resolution scanning microscope, led to the formation of a percolated network at both concentrations. It resulted in the electrical conductivity of 3.38 S/m achieved for 10 wt% with a bonding strength of 4.8 MPa examined by a lap shear test. Compared to neat copolyamide, Young’s modulus increased up to 0.6 GPa and tensile strength up to 30.4 MPa. The carbon nanotubes improved the thermal stability of 20 °C and shifted the glass transition of 10 °C to a higher value. The very low viscosity of the neat adhesive increased about 5–6 orders of magnitude at both concentrations, even at elevated temperatures. With a simultaneous growth in storage and loss modulus this indicates the strong interactions between polymer and carbon nanotubes.

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Aikawa, Shunsuke, Yugang Zhao e Jiwang Yan. "Development of High-Sensitivity Electrically Conductive Composite Elements by Press Molding of Polymer and Carbon Nanofibers". Micromachines 13, n.º 2 (23 de janeiro de 2022): 170. http://dx.doi.org/10.3390/mi13020170.

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Carbon nanofibers (CNFs) have various excellent properties, such as high tensile strength, electric conductivity and current density resistance, and thus have great application potential in electrical sensor development. In this research, electrically conductive composite elements using CNFs sandwiched by thermoplastic olefin (TPO) substrates were developed by press molding. The metal mold used for press molding was processed by a femtosecond laser to generate laser-induced periodic surface structures (LIPSS) on the mold surface. The aggregate of CNFs was then flexibly fixed by the LIPSSs imprinted on the TPO substrate surface to produce a wavy conductive path of CNFs. The developed composite elements exhibited a sharp increase in electrical resistance as strain increased. A high gauge factor of over 47 was achieved, which demonstrates high sensitivity against strain when the composite element is used as a strain gauge. Scanning electron microscope observation revealed that the TPO filled the spaces in the aggregate of CNFs after press molding, and the conductive path was extended by the tensile strain. The strain-induced dynamic changes of contact states of CNFs and CNFs networks are discussed based on the electrical performance measurement and cross-sectional observation of the elements. This research provides a new approach to the production of flexible and high sensitivity strain sensors.

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Koncar, V., C. Cochrane, M. Lewandowski, F. Boussu e C. Dufour. "Electro‐conductive sensors and heating elements based on conductive polymer composites". International Journal of Clothing Science and Technology 21, n.º 2/3 (27 de fevereiro de 2009): 82–92. http://dx.doi.org/10.1108/09556220910933808.

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PurposeThe need for sensors and actuators is an important issue in the field of smart textiles and garments. Important developments in sensing and heating textile elements consist in using non‐metallic yarns, for instance carbon containing fibres, directly in the textile fabric. Another solution is to use electro‐conductive materials based on conductive polymer composites (CPCs) containing carbon or metallic particles. The purpose of this paper is to describe research based on the use of a carbon black polymer composite to design two electro‐conductive elements: a strain sensor and a textile heating element.Design/methodology/approachThe composite is applied as a coating consisting of a solvent, a thermoplastic elastomer, and conductive carbon black nanoparticles. In both applications, the integration of the electrical wires for the voltage supply or signal recording is as discreet as possible.FindingsThe CPC materials constitute a well‐adapted solution for textile structures: they are very flexible, and thus do not modify the mechanical characteristics and general properties of the textile structure.Research limitations/implicationsIn the case of the heating element, the use of metallic yarns as electrodes makes the final structure a more rigid. This can be improved by choosing other conducting yarns that are more flexible, or by developing knitted structures instead of woven fabrics.Practical implicationsThe CPC provide a low cost solution, and the elements are usually designed so as to work with a low voltage supply.Originality/valueThe CPC has been prepared with a solvent process which is especially adapted to flexible materials like textiles. This is original in comparison to the conventional melt‐mixing process usually found in literature.

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Dydek, Kamil, Anna Boczkowska, Paulina Latko-Durałek, Małgorzata Wilk, Karol Padykuła e Rafał Kozera. "Effect of the areal weight of CNT-doped veils on CFRP electrical properties". Journal of Composite Materials 54, n.º 20 (23 de janeiro de 2020): 2677–85. http://dx.doi.org/10.1177/0021998320902227.

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The main goal of this work was the increasing electrical conductivity of carbon-epoxy composites due to implementation of thermoplastic nonwoven veils doped with carbon nanotubes into the composite structure. Nonwovens which differ in areal weight were produced by extrusion of fibers and their thermal pressing. Laminates were fabricated using an out-of-autoclave method and nonwovens were incorporated between each layer of carbon-epoxy unidirectional prepreg. The applied conductive nonwovens improved surface and volume electrical conductivity of carbon fibre reinforced polymer in all directions. Microstructure observations proved a very high quality of the fabricated composites. The implementation of nonwovens affected the crack propagation under loading.

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Peidayesh, Hamed, Katarína Mosnáčková, Zdenko Špitalský, Abolfazl Heydari, Alena Opálková Šišková e Ivan Chodák. "Thermoplastic Starch–Based Composite Reinforced by Conductive Filler Networks: Physical Properties and Electrical Conductivity Changes during Cyclic Deformation". Polymers 13, n.º 21 (4 de novembro de 2021): 3819. http://dx.doi.org/10.3390/polym13213819.

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Conductive polymer composites (CPC) from renewable resources exhibit many interesting characteristics due to their biodegradability and conductivity changes under mechanical, thermal, chemical, or electrical stress. This study is focused on investigating the physical properties of electroconductive thermoplastic starch (TPS)–based composites and changes in electroconductive paths during cyclic deformation. TPS–based composites filled with various carbon black (CB) contents were prepared through melt processing. The electrical conductivity and physicochemical properties of TPS–CB composites, including mechanical properties and rheological behavior, were evaluated. With increasing CB content, the tensile strength and Young’s modulus were found to increase substantially. We found a percolation threshold for the CB loading of approximately 5.5 wt% based on the rheology and electrical conductivity. To observe the changing structure of the conductive CB paths during cyclic deformation, both the electrical conductivity and mechanical properties were recorded in parallel using online measurements. Moreover, the instant electrical conductivity measured online during mechanical deformation of the materials was taken as the parameter indirectly describing the structure of the conductive CB network. The electrical conductivity was found to increase during five runs of repeated cyclic mechanical deformations to constant deformation below strain at break, indicating good recovery of conductive paths and their new formation.

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Fazi, Laura, Carla Andreani, Cadia D’Ottavi, Leonardo Duranti, Pietro Morales, Enrico Preziosi, Anna Prioriello et al. "Characterization of Conductive Carbon Nanotubes/Polymer Composites for Stretchable Sensors and Transducers". Molecules 28, n.º 4 (13 de fevereiro de 2023): 1764. http://dx.doi.org/10.3390/molecules28041764.

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The increasing interest in stretchable conductive composite materials, that can be versatile and suitable for wide-ranging application, has sparked a growing demand for studies of scalable fabrication techniques and specifically tailored geometries. Thanks to the combination of the conductivity and robustness of carbon nanotube (CNT) materials with the viscoelastic properties of polymer films, in particular their stretchability, “surface composites” made of a CNT on polymeric films are a promising way to obtain a low-cost, conductive, elastic, moldable, and patternable material. The use of polymers selected for specific applications, however, requires targeted studies to deeply understand the interface interactions between a CNT and the surface of such polymer films, and in particular the stability and durability of a CNT grafting onto the polymer itself. Here, we present an investigation of the interface properties for a selected group of polymer film substrates with different viscoelastic properties by means of a series of different and complementary experimental techniques. Specifically, we studied the interaction of a single-wall carbon nanotube (SWCNT) deposited on two couples of different polymeric substrates, each one chosen as representative of thermoplastic polymers (i.e., low-density polyethylene (LDPE) and polypropylene (PP)) and thermosetting elastomers (i.e., polyisoprene (PI) and polydimethylsiloxane (PDMS)), respectively. Our results demonstrate that the characteristics of the interface significantly differ for the two classes of polymers with a deeper penetration (up to about 100 μm) into the polymer bulk for the thermosetting substrates. Consequently, the resistance per unit length varies in different ranges, from 1–10 kΩ/cm for typical thermoplastic composite devices (30 μm thick and 2 mm wide) to 0.5–3 MΩ/cm for typical thermosetting elastomer devices (150 μm thick and 2 mm wide). For these reasons, the composites show the different mechanical and electrical responses, therefore suggesting different areas of application of the devices based on such materials.

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Serban, Daniiel, Laurentia Alexandrescu e Constantin Gheorghe Opran. "Research Regarding Molding of Fuel Cell Bipolar Plates Made of Polymeric-Carbon Composites". Materials Science Forum 957 (junho de 2019): 369–78. http://dx.doi.org/10.4028/www.scientific.net/msf.957.369.

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Fuel cells are electrochemical devices that convert chemical energy of fuels into electrical energy. Fuel cells were used in NASA space programs to generate energy to satellites and space capsules. Today fuel cells are used to power vehicles including automobiles, forklifts, buses, boats, motorcycles or submarines. Bipolar plates are components of the fuel cell stack and must be highly electrically conductive to obtain a good voltage across the stack and highly thermally conductive to help cooling. Bipolar plates were made of graphite and stainless steel to which additional surface treatments were added to improve properties. In order to reduce the costs of bipolar plates researchers were looking for alternatives: polymeric thermosets and thermoplastics composites. In our paper we analyse the composites polyethylene-carbon and polypropylene-carbon for which we investigated the mechanical properties for the compression-moulded samples. The mechanical, the electrical properties and flow length and the cavity pressure were analysed for the injection moulding in polyethylene-carbon with micro-profiles of 0.5mm x 0.2mm.

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Phua, Jin-Luen, Pei-Leng Teh, Supri Abdul Ghani e Cheow-Keat Yeoh. "Comparison study of carbon black (CB) used as conductive filler in epoxy and polymethylmethacrylate (PMMA)". Journal of Polymer Engineering 36, n.º 4 (1 de maio de 2016): 391–98. http://dx.doi.org/10.1515/polyeng-2015-0026.

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Abstract A comparison study between carbon black (CB) filled thermoset (epoxy) and thermoplastic, polymethylmethacrylate (PMMA), was done in this research. CB was introduced as the conductive filler in epoxy and PMMA at different filler loading, which ranged from 5 vol.% to 20 vol.%. The physical, mechanical, electrical and thermal stability properties were investigated. The incorporation of CB into both epoxy and PMMA increased the density, improved the thermal stability and electrical conductivity of the composites, reduced the coefficient of thermal expansion and weakened the flexural and fracture toughness properties of the composites.

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Araya-Hermosilla, Rodrigo, Andrea Pucci, Patrizio Raffa, Dian Santosa, Paolo Pescarmona, Régis Gengler, Petra Rudolf, Ignacio Moreno-Villoslada e Francesco Picchioni. "Electrically-Responsive Reversible Polyketone/MWCNT Network through Diels-Alder Chemistry". Polymers 10, n.º 10 (28 de setembro de 2018): 1076. http://dx.doi.org/10.3390/polym10101076.

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This study examines the preparation of electrically conductive polymer networks based on furan-functionalised polyketone (PK-Fu) doped with multi-walled carbon nanotubes (MWCNTs) and reversibly crosslinked with bis-maleimide (B-Ma) via Diels-Alder (DA) cycloaddition. Notably, the incorporation of 5 wt.% of MWCNTs results in an increased modulus of the material, and makes it thermally and electrically conductive. Analysis by X-ray photoelectron spectroscopy indicates that MWCNTs, due to their diene/dienophile character, covalently interact with the matrix via DA reaction, leading to effective interfacial adhesion between the components. Raman spectroscopy points to a more effective graphitic ordering of MWCNTs after reaction with PK-Fu and B-Ma. After crosslinking the obtained composite via the DA reaction, the softening point (tan(δ) in dynamic mechanical analysis measurements) increases up to 155 °C, as compared to the value of 130 °C for the PK-Fu crosslinked with B-Ma and that of 140 °C for the PK-Fu/B-Ma/MWCNT nanocomposite before resistive heating (responsible for crosslinking). After grinding the composite, compression moulding (150 °C/40 bar) activates the retro-DA process that disrupts the network, allowing it to be reshaped as a thermoplastic. A subsequent process of annealing via resistive heating demonstrates the possibility of reconnecting the decoupled DA linkages, thus providing the PK networks with the same thermal, mechanical, and electrical properties as the crosslinked pristine systems.

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Smaranda, Ion, Andreea Nila, Paul Ganea, Monica Daescu, Irina Zgura, Romeo C. Ciobanu, Alexandru Trandabat e Mihaela Baibarac. "The Influence of the Ceramic Nanoparticles on the Thermoplastic Polymers Matrix: Their Structural, Optical, and Conductive Properties". Polymers 13, n.º 16 (18 de agosto de 2021): 2773. http://dx.doi.org/10.3390/polym13162773.

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This paper prepared composites under the free membranes form that are based on thermoplastic polymers of the type of polyurethane (TPU) and polyolefin (TPO), which are blended in the weight ratio of 2:1, and ceramic nanoparticles (CNs) such as BaSrTiO3 and SrTiO3. The structural, optical, and conductive properties of these new composite materials are reported. The X-ray diffraction studies highlight a cubic crystalline structure of these CNs. The main variations in the vibrational properties of the TPU:TPO blend induced by CNs consist of the following: (i) the increase in the intensity of the Raman line of 1616 cm−1; (ii) the down-shift of the IR band from 800 to 791 cm−1; (iii) the change of the ratio between the absorbance of IR bands localized in the spectral range 950–1200 cm−1; and (iv) the decrease in the absorbance of the IR band from 1221 cm−1. All these variations were correlated with a preferential adsorption of thermoplastic polymers on the CNs surface. A photoluminescence (PL) quenching process of thermoplastic polymers is demonstrated to occur in the presence of CNs. The anisotropic PL measurements have highlighted a change in the angle of the binding of the TPU:TPO blend, which varies from 23.7° to ≈49.3° and ≈53.4°, when the concentration of BaSrTiO3 and SrTiO3 CNs, respectively, is changed from 0 to 25 wt. %. Using dielectric spectroscopy, two mechanisms are invoked to take place in the case of the composites based on TPU:TPO blends and CNs, i.e., one regarding the type of the electrical conduction and another specifying the dielectric–dipolar relaxation processes.

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Hamdi, Khalil, Zoheir Aboura, Walid Harizi e Kamel Khellil. "Structural health monitoring of carbon fiber reinforced matrix by the resistance variation method". Journal of Composite Materials 54, n.º 25 (23 de abril de 2020): 3919–30. http://dx.doi.org/10.1177/0021998320921476.

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In this work, electrical resistance change method is used for carbon fiber reinforced thermoplastic polymers damage monitoring. The electrical resistance variation could be an interesting complementary to existing/classical damage monitoring methods. It is extremely attributed to electrical conductivity of composite material and it appears that enhancing the conductivity of materials, by the use of conductive nanofillers in our case, improves their sensitivity to mechanical loading. Carbon fiber reinforced thermoplastic polymers with different nanofillers types and concentrations were manufactured and tested in tensile loading. Concentration of 0 and 8 wt% of carbon black and 2.5 wt% of carbon nanotubes were used with Polyamide 6 sheets as matrix. Nanofillers weakening effect was discussed according to their concentrations and types. The acoustic emission, digital image correlation and in-situ microscopy were also recorded during testing. A correlation between all these signals and the evolution of the electrical resistance of the composites during the tensile loading was performed. It was found that CB enhances sensitivity of carbon fiber reinforced thermoplastic polymers to damage detection, especially delamination. For the carbon nanotubes, results are less promising. A discussion is held about the nanofillers concentration influence.

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Frederick, Harry, Wencai Li e Genevieve Palardy. "Disassembly Study of Ultrasonically Welded Thermoplastic Composite Joints via Resistance Heating". Materials 14, n.º 10 (12 de maio de 2021): 2521. http://dx.doi.org/10.3390/ma14102521.

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This manuscript explores the disassembly potential of ultrasonically welded thermoplastic composite joints for reuse or recycling through resistance heating via a nanocomposite film located at the welded interface. Nanocomposite films containing multi-walled carbon nanotubes (MWCNTs) were characterized for thermo-electrical behavior to assess self-heating. It was generally observed that maximum temperature increased with MWCNT and film thickness. To demonstrate potential for disassembly, glass fiber/polypropylene adherends were welded with nanocomposite films. Shear stress during disassembly was measured for three initial adherend’s surface temperatures. It was found that the required tensile load decreased by over 90% at the highest temperatures, effectively demonstrating the potential for disassembly via electrically conductive films. Fracture surfaces suggested that disassembly was facilitated through a combination of nanocomposite and matrix melting and weakened fiber–matrix interface. Limitations, such as slow heating rates and the loss of contact at the interface, imply that the method could be more suited for recycling, instead of repair and reuse, as the heat-affected zone extended through the adherends’ thickness at the overlap during heating.

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Li, Ting, Li-Feng Ma, Rui-Ying Bao, Guo-Qiang Qi, Wei Yang, Bang-Hu Xie e Ming-Bo Yang. "A new approach to construct segregated structures in thermoplastic polyolefin elastomers towards improved conductive and mechanical properties". Journal of Materials Chemistry A 3, n.º 10 (2015): 5482–90. http://dx.doi.org/10.1039/c5ta00314h.

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Brunella, Valentina, Beatrice Gaia Rossatto, Domenica Scarano e Federico Cesano. "Thermal, Morphological, Electrical Properties and Touch-Sensor Application of Conductive Carbon Black-Filled Polyamide Composites". Nanomaterials 11, n.º 11 (17 de novembro de 2021): 3103. http://dx.doi.org/10.3390/nano11113103.

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Polyamide 66 (PA66) is a well-known engineering thermoplastic polymer, primarily employed in polymer composites with fillers and additives of different nature and dimensionality (1D, 2D and 3D) used as alternatives to metals in various technological applications. In this work, carbon black (CB), a conductive nanofiller, was used to reinforce the PA66 polymer in the 9–27 wt. % CB loading range. The reason for choosing CB was intrinsically associated with its nature: a nanostructured carbon filler, whose agglomeration characteristics affect the electrical properties of the polymer composites. Crystallinity, phase composition, thermal behaviour, morphology, microstructure, and electrical conductivity, which are all properties engendered by nanofiller dispersion in the polymer, were investigated using thermal analyses (thermogravimetry and differential scanning calorimetry), microscopies (scanning electron and atomic force microscopies), and electrical conductivity measurements. Interestingly, direct current (DC) electrical measurements and conductive-AFM mapping through the samples enable visualization of the percolation paths and the ability of CB nanoparticles to form aggregates that work as conductive electrical pathways beyond the electrical percolation threshold. This finding provides the opportunities to investigate the degree of filler dispersion occurring during the transformation processes, while the results of the electrical properties also contribute to enabling the use of such conductive composites in sensor and device applications. In this regard, the results presented in this paper provide evidence that conductive carbon-filled polymer composites can work as touch sensors when they are connected with conventional low-power electronics and controlled by inexpensive and commercially available microcontrollers.

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Im, Kwang-Hee, David K. Hsu, Chien-Ping Chiou, Daniel J. Barnard, Jong-An Jung e In-Young Yang. "Terahertz Wave Approach and Application on FRP Composites". Advances in Materials Science and Engineering 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/563962.

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Terahertz (THz) applications have emerged as one of the most new powerful nondestructive evaluation (NDE) techniques. A new T-ray time-domain spectroscopy system was utilized for detecting and evaluating orientation influence in carbon fiber-reinforced plastics (CFRPs) composite laminates. Investigation of terahertz time-domain spectroscopy (THz-TDS) was made, and reflection and transmission configurations were studied as a nondestructive evaluation technique. Here, the CFRP composites derived their excellent mechanical strength, stiffness, and electrical conductivity from carbon fibers. Especially, the electrical conductivity of the CFRP composites depends on the direction of unidirectional fibers since carbon fibers are electrically conducting while the epoxy matrix is not. In order to solve various material properties, the index of refraction (n) and the absorption coefficient (α) are derived in reflective and transmission configurations using the terahertz time-domain spectroscopy. Also, for a 48-ply thermoplastic polyphenylene-sulfide-(PPS-) based CFRP solid laminate and nonconducting materials, the terahertz scanning images were made at the angles ranged from0°to180°with respect to the nominal fiber axis. So, the images were mapped out based on the electrical field (E-field) direction in the CFRP solid laminates. It is found that the conductivity (σ) depends on the angles of the nominal axis in the unidirectional fiber.

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Yong, K. C. "Preparation and Characterisation of Electrically Conductive Thermoplastic Vulcanisate Based on Natural Rubber and Polypropylene Blends with Polyaniline". Polymers and Polymer Composites 24, n.º 3 (março de 2016): 225–32. http://dx.doi.org/10.1177/096739111602400307.

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Santos, Andrey M., Claudia Merlini, Sílvia D. A. S. Ramôa e Guilherme M. O. Barra. "Comparative study of electrically conductive polymer composites of polyester‐based thermoplastic polyurethane matrix with polypyrrole and montmorillonite/polypyrrole additive". Polymer Composites 41, n.º 5 (31 de janeiro de 2020): 2003–12. http://dx.doi.org/10.1002/pc.25515.

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Kamalov, Almaz, Mikhail Shishov, Natalia Smirnova, Vera Kodolova-Chukhontseva, Irina Dobrovol’skaya, Konstantin Kolbe, Andrei Didenko, Elena Ivan’kova, Vladimir Yudin e Pierfrancesco Morganti. "Influence of Electric Field on Proliferation Activity of Human Dermal Fibroblasts". Journal of Functional Biomaterials 13, n.º 3 (29 de junho de 2022): 89. http://dx.doi.org/10.3390/jfb13030089.

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In this work, an electrically conductive composite based on thermoplastic polyimide and graphene was obtained and used as a bioelectrode for electrical stimulation of human dermal fibroblasts. The values of the electrical conductivity of the obtained composite films varied from 10−15 to 102 S/m with increasing graphene content (from 0 to 5.0 wt.%). The characteristics of ionic and electronic currents flowing through the matrix with the superposition of cyclic potentials ± 100 mV were studied. The high stability of the composite was established during prolonged cycling (130 h) in an electric field with a frequency of 0.016 Hz. It was established that the composite films based on polyimide and graphene have good biocompatibility and are not toxic to fibroblast cells. It was shown that preliminary electrical stimulation increases the proliferative activity of human dermal fibroblasts in comparison with intact cells. It is revealed that an electric field with a strength E = 0.02–0.04 V/m applied to the polyimide films containing 0.5–3.0 wt.% of the graphene nanoparticles activates cellular processes (adhesion, proliferation).

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Setnescu, Radu, Eduard-Marius Lungulescu e Virgil Emanuel Marinescu. "Polymer Composites with Self-Regulating Temperature Behavior: Properties and Characterization". Materials 16, n.º 1 (24 de dezembro de 2022): 157. http://dx.doi.org/10.3390/ma16010157.

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A novel conductive composite material with homogeneous binary polymer matrix of HDPE (HD) and LLDPE (LLD), mixed with conductive filler consisting of carbon black (CB) and graphite (Gr), was tested against a HDPE composite with a similar conductive filler. Even the concentration of the conductive filler was deliberately lower for (CB + Gr)/(LLD + HD), and the properties of this composite are comparable or better to those of (CB + Gr)/HD. The kinetic parameters of the ρ-T curves and from the DSC curves indicate that the resistivity peak is obtained when the polymer matrix is fully melted. When subjected to repeated thermal cycles, the composite (CB + Gr)/(LLD + HD) presented a better electrical behavior than composite CB + Gr)/HD, with an increase in resistivity (ρmax) values with the number of cycles, as well as less intense NTC (Negative Temperature Coefficient) effects, both for the crosslinked and thermoplastic samples. Radiation crosslinking led to increased ρmax values, as well as to inhibition of NTC effects in both cases, thus having a clear beneficial effect. Limitation effects of surface temperature and current intensity through the sample were observed at different voltages, enabling the use of these materials as self-regulating heating elements at various temperatures below the melting temperature. The procedure based on physical mixing of the components appears more efficient in imparting lower resistivity in solid state and high PTC (Positive Temperature Coefficient) effects to the composites. This effect is probably due to the concentration of the conductive particles at the surface of the polymer domains, which would facilitate the formation of the conductive paths. Further work is still necessary to optimize both the procedure of composite preparation and the properties of such materials.

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Zheng, Shihao, Bing Wang, Xiaojie Zhang e Xiongwei Qu. "Amino Acid-Assisted Sand-Milling Exfoliation of Boron Nitride Nanosheets for High Thermally Conductive Thermoplastic Polyurethane Composites". Polymers 14, n.º 21 (2 de novembro de 2022): 4674. http://dx.doi.org/10.3390/polym14214674.

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Boron nitride nanosheets (BNNSs) show excellent thermal, electrical, optical, and mechanical properties. They are often used as fillers in polymers to prepare thermally conductive composites, which are used in the production of materials for thermal management, such as electronic packaging. Aside from the van der Waals force, there are some ionic bond forces between hexagonal boron nitride (h-BN) layers that result in high energy consumption and make BNNSs easily agglomerate. To overcome this issue, L-lysine (Lys) was first employed as a stripping assistant for preparing graft-functionalized BNNSs via mechanical sand-milling technology, and the obtained Lys@BNNSs can be added into thermoplastic polyurethane (TPU) by solution mixing and hot-pressing methods to prepare thermally conductive composites. This green and scalable method of amino acid-assisted sand-milling can not only exfoliate the bulk h-BN successfully into few-layer BNNSs but also graft Lys onto the surface or edges of BNNSs through Lewis acid–base interaction. Furthermore, benefiting from Lys’s highly reactive groups and biocompatibility, the compatibility between functionalized BNNSs and the TPU matrix is significantly enhanced, and the thermal conductivity and mechanical properties of the composite are remarkably increased. When the load of Lys@BNNSs is 3 wt%, the thermal conductivity and tensile strength of the obtained composites are 90% and 16% higher than those of the pure TPU, respectively. With better thermal and mechanical properties, Lys@BNNS/TPU composites can be used as a kind of heat dissipation material and have potential applications in the field of thermal management materials.

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Guo, Rui, Zechun Ren, Hongjie Bi, Min Xu e Liping Cai. "Electrical and Thermal Conductivity of Polylactic Acid (PLA)-Based Biocomposites by Incorporation of Nano-Graphite Fabricated with Fused Deposition Modeling". Polymers 11, n.º 3 (22 de março de 2019): 549. http://dx.doi.org/10.3390/polym11030549.

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The aim of the study was to improve the electrical and thermal conductivity of the polylactic acid/wood flour/thermoplastic polyurethane composites by Fused Deposition Modeling (FDM). The results showed that, when the addition amount of nano-graphite reached 25 pbw, the volume resistivity of the composites decreased to 108 Ω·m, which was a significant reduction, indicating that the conductive network was already formed. It also had good thermal conductivity, mechanical properties, and thermal stability. The adding of the redox graphene (rGO) combined with graphite into the composites, compared to the tannic acid-functionalized graphite or the multi-walled carbon nanotubes, can be an effective method to improve the performance of the biocomposites, because the resistivity reduced by one order magnitude and the thermal conductivity increased by 25.71%. Models printed by FDM illustrated that the composite filaments have a certain flexibility and can be printed onto paper or flexible baseplates.

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Duan, Chenqi, Fei Long, Xiaolu Shi, Yuting Wang, Jiajing Dong, Songtao Ying, Yesheng Li et al. "MWCNTs-GNPs Reinforced TPU Composites with Thermal and Electrical Conductivity: Low-Temperature Controlled DIW Forming". Micromachines 14, n.º 4 (4 de abril de 2023): 815. http://dx.doi.org/10.3390/mi14040815.

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As an effective technique for fabricating conductive and thermally conductive polymer composites, a multi-filler system incorporates different types and sizes of multiple fillers to form interconnected networks with improved electrical, thermal, and processing properties. In this study, DIW forming of bifunctional composites was achieved by controlling the temperature of the printing platform. The study was based on enhancing the thermal and electrical transport properties of hybrid ternary polymer nanocomposites with multi-walled carbon nanotubes (MWCNTs) and graphene nanoplates (GNPs). With thermoplastic polyurethane (TPU) used as the matrix, the addition of MWCNTs, GNPs and both mixtures further improved the thermal conductivity of the elastomers. By adjusting the weight fraction of the functional fillers (MWCNTs and GNPs), the thermal and electrical properties were gradually explored. Here, the thermal conductivity of the polymer composites increased nearly sevenfold (from 0.36 W·m−1·k−1 to 2.87 W·m−1·k−1) and the electrical conductivity increased up to 5.49 × 10−2 S·m−1. It is expected to be used in the field of electronic packaging and environmental thermal dissipation, especially for modern electronic industrial equipment.

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