Search

Antibacterial materials are one of the important materials in our daily lives, especially in the medicine where antibacterial efficacy is indispensable. Moreover, the precise electronic instrument also requires highly electromagnetic interference shielding effectiveness (EMI SE) and as such to prevent mutual interference. Therefore, the acquisition of antibacterial property and EMI SE is essential. In this study, carbon nanotube (CNT) and triclosan (TCS) are used as conductive and antibacterial substances separately during the production of polypropylene (PP)-based antibacterial and conductive composite planks. The planks are tested for a series of physical property tests, EMI SE measurement, and antibacterial efficacy as related to the CNT content and the TCS content. The test results indicate regardless of whether it is CNT or TCS that is added, the planks exhibit good crystallinity. Furthermore, the presence of TCS contributes good antibacterial efficacy against staphylococcus aureus (S. Aureus), and the antibacterial efficacy effectuated by 0.1 wt% TCS also meets the related EU standard. In addition, the incorporation of both CNT and TCS adversely affects the EMI SE of the planks, but the resulting EMI SE remains to be between −15 dB and −20 dB. [ABSTRACT FROM AUTHOR]

The rapid development of wireless communication and electronic equipment requires active measures to eliminate electromagnetic radiation hazards. Based on the layered assembly strategy, MXene-based composite fabric with multiple functional layers was prepared by combining two-dimensional transition metal (MXene) with PP substrate by a simple solution dipping method. PP substrate endowed pure MXene film certain mechanical properties, and polydopamine modification on the surface of PP enhanced the bonding fastness between the substrate and MXene layer. The silicon-containing hydrophobic layer imparted hydrophobic properties to the conductive fabric, thus ensuring the stability of the conductivity of the MXene layer when used in complex environments. The results shown that the conductivity and electromagnetic shielding effectiveness (EMI SE) of the composite fabric increased with the increased in impregnation times. When the impregnation times were three, the conductivity and EMI SE of the composite fabric were 6.54 S/cm and 32.57 dB, respectively. After hydrophobic treatment, the contact angle of the composite fabric was 140.49°. In addition, the average EMI SE and shielding efficiency still reached 25.12 dB and 99.69%. The excellent EMI shielding capability coupled with favorable bendability endows MXene-based composite fabric to be an alternative choice in electronics, aerospace and smart wearables. [ABSTRACT FROM AUTHOR]

With the development of modern electronic technology, there is an urgent need to prepare multifunctional polymer composite materials with flame retardant and electromagnetic shielding functions. Herein, use the chemical activity of polydopamine (PDA) to modify polyphenylene (PP) fabric to enhance its interface compatibility. Then, the dipping method was used to achieve the successful deposition of Ag nanoparticles on the surface of the PP non‐woven fabric, and by adjusting the concentration of the Ag precursor and the immersion time of the flame retardant constructed a conductive composite material with lightweight, flexible and has good flame retardant properties. The results showed that when the concentration of AgNO3 solution was 2% and the thickness was 0.166 mm, the average shielding effectiveness shielding effectiveness (SE) and SSE/t of the composite fabric reached 25.01 dB and 6097.56 dB cm2g−1, respectively. In particular, the composite fabric still maintained stable electrical conductivity after flame retardant treatment, and the average shielding effectiveness SE and SSE/t of the composite fabric reached 20.20 dB and 1518.80 dB cm2 g−1. The multifunctional conductive composite fabric prepared in this study has broad development prospects in the fields of electromagnetic shielding and smart wear. [ABSTRACT FROM AUTHOR]

The aim of this study is to combine conductive polymer composite with conductive fabrics for the acquisition of electromagnetic interference shielding effectiveness (EMI SE) materials. HS-PET filaments, 316 L stainless steel (SS) wires, and bamboo charcoal (BC) roving are made into woven fabrics and knitted fabrics. Unlike the nonwoven fabrics that consist of entangled staple fibers, the resulting shielding materials have greater air permeability. Accordingly, HS-PET filaments, 316 L SS filaments, and BC roving are made into conductive yarns with different twists per inch (T.P.I.) using a ring spinning manufacture. The conductive yarns are made into woven and knitted fabrics, the electromagnetic interference shielding effectiveness (EMI SE) of which are then evaluated in order to examine the influences of the number of fabric layers, lamination angle, and laminated fabric type. The test results show that with a T.P.I being 8, the conductive yarns have an optimal tensile strength of 43.74 N with the lowest CV% of 4.72%. In the meantime, the conductive yarns have good uniformity but do not demonstrate any significant trend on the linear resistance. In addition, the conductive woven fabrics have better tensile strength along the weft direction (712.49 N). Regardless of whether it is a woven fabric or a knitted fabric, the surface resistivity is 107 Ω/sq. Single-layered knitted fabrics have the optimal air permeability (262.6 cm3/s/cm2), and the three-layered woven fabrics laminated at angle of 0°/90°/45° exhibit the maximum EMI SE (-45.96 dB). Therefore, the three parameters are correlated with the metallic conductive network that directly changes the EMI SE of the resulted fabrics and composites. [ABSTRACT FROM AUTHOR]

This study aims to combine carbon fibers and copper metallic wires using a rotary twister, and the employment of wire coating technique reinforces the mechanical properties of carbon fibers, creating more feasible applications. The proposed carbon (C)/copper (Cu)/polyester (PET)/polypropylene (PP)/acrylic (A) woven fabrics preserve the electrical conductivity of carbon fibers and metallic wires while maintaining the thin and soft features of woven fabrics. In addition to good electrical conductivity, wire coating technique provides the coated wires with greater mechanical properties, including tensile strength, elongation, bending torsion, creep resistance, and wear‐resistant property. The proposed manufacturing design contributes to an innovative production without interfering with the intrinsic properties of materials, which also broadens the application range of the electromagnetic interference shielding effectiveness products. [ABSTRACT FROM AUTHOR]

With the significant advances in electronic products, materials with good flexibility, corrosion resistance, high electrical conductivity and minimal thickness are urgently needed. Herein, we demonstrate the biomimetic core–shell structure of lightweight, flexible, self-cleaning nanofiber films for high-performance electromagnetic interference (EMI) shielding by tuning the deposition of Ag nanoparticles (AgNPs). With a thickness of 0.06 mm, PAN@TiO2@AgNPs composite films (PTA films) exhibit an average EMI shielding effectiveness (SE) of 82.60 dB. After further processing with fluorine-containing molecules, the PTA-4 film becomes superhydrophobic and anticorrosive. After a hydrophobic treatment, composite films have average SE, specific SE (SSE) and SSE/t being 79.57 dB, 360.86 dB cm3 g−1, and 60143.33 dB cm2 g−1, respectively. In particular, conductive films that undergo UV radiation and bending cycles retain a stabilized electrical conductivity. This tuning bio-inspired fabrication method provides the films with UV-resistance, superhydrophobicity and EMI SE that fit the practical applications of wearable and flexible sensors. [ABSTRACT FROM AUTHOR]

Multiwalled carbon nanotubes (MWCNTs) have extraordinary electrical conductivity but limited applications due to the ease of agglomeration, especially in thermoplastic composite. With the aim of achieving high electromagnetic interference shielding performance by applying MWCNTs in thermoplastic matrix, MWCNTs were made into buckypaper (BP) and then hot pressed with PP/PLA/TiO2 hybrid films, forming sandwich‐structured BP/PP‐PLA‐TiO2 hybrid composite films. BP was examined in terms of morphology, cell structure, and electrical conductivity, while BP/PP‐PLA‐TiO2 hybrid composite film was tested for electromagnetic shielding effectiveness (EMSE), thermal properties and UV‐cut efficacy. It was found that using vacuum filtration successfully produced BP with a smooth and sleek surface and an even porosity ranging between 20 and 45 nm. The electrical conductivity of BP was proportional to its thickness. About 90 μm‐thick BP had 75.62% lower surface resistivity and 36.63% higher electrical conductivity than 30 μm‐thick BP. Moreover, the EMSE of BP/PP‐PLA‐TiO2 composite film increased as a result of the higher thickness of BP. When the thickness of BPs was 90 μm, the BP/PP‐PLA‐TiO2 composite film had an average EMSE of 40 dB at 0–3 GHz and a peak of 70 dB, and 119% higher tensile strength and 11% higher elastic modulus than those of PP/PLA/TiO2 composite film. BP/PP‐PLA‐TiO2 composite film had UV‐cut efficacy that was close to 0%. The addition of BP was proven to improve the crystallization and thermal stability. POLYM. COMPOS., 40:3065–3074, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Protective clothing with electromagnetic shielding effectiveness (EMSE) is a functional textile, which shields electromagnetic waves to protect the human body from the far infrared rays. Traditional EMSE garments primarily use metallic plates for reflecting electromagnetic interference (EMI). However, they also have disadvantages of a heavy weight, easy corrosion, and high production cost. In this study, three different functional yarns are combined, during which the twist number of metallic wires is changed for a better shielding effect. A crochet machine is used to fabricate functional elastic knits with the metallic composite yarns as the warp- and weft-inlaid yarns. The test results show that double (D) functional elastic knits exhibit EMSE of above 20 dB when the EMI are between 1.0 and 3.0 GHz. In addition, the knit structure can improve breaking tensile strength by 170 % and increases bursting strength by 58 %, but undermines the tear strength by 10 %. Although changing twist number of metallic composite yarns does not affect water absorption rate along the weft direction, it helps increasing elastic recovery rate by 3.1 %, water absorption rate along the warp direction by 106 %, far-infrared emissivity by 2.3 %, water vapor transmission rate by 20 %, and air permeability by 6 %. [ABSTRACT FROM AUTHOR]

Electromagnetic pollution interferes with electronic equipment in proximity and jeopardizes human health, which urges the development of electromagnetic interference (EMI) shielding materials. It is urgent to develop electromagnetic interference (EMI) shielding materials. However, the preparation of materials with superhydrophobicity, flame retardancy and EMI shielding properties is still challenging. In this study, we invented a core-spun yarn feeding device, which uses polysulfonamide (PSA) roving as a coating material and stainless steel wire as the core material to prepare a conductive core-spun yarn, which solves the problem of the wire having an easily exposed fabric surface. The finally prepared conductive fabric was subjected to Waterproof 2P hydrophobic treatment to form a superhydrophobic flame-retardant EMI shielding fabric. The results show that the hydrophobic treatment creates a thin film over the woven fabrics, and the contact angle of the fabric surface can reach 155°. The hydrophobic treatment will not damage the shielding effect and slightly increase the dB value. The average dB value of PSA-SS-1' and PSA-SS-2' are increased by 0.82 dB and 1.92 dB, respectively. When composed of conductive wrapped yarns for both the warp and weft yarns, the electromagnetic interference shielding effectiveness (EMI SE) of conductive fabrics is beyond 30 dB at 0–3000 MHz and the burnt depth is shorter than 40 mm. As for real applications, superhydrophobic/flame retardant/EMI SE fabrics can be used in a moist and complex environment with retaining conductivity and shielding effectiveness. [ABSTRACT FROM AUTHOR]

Polypropylene (PP)/multi-walled carbon nanotube (MWCNT) coated polyethylene terephthalate (PET) yarns are made into conductive woven/knitted fabrics. The fabric structure, tensile properties, static bursting properties, electrical resistivity, and electromagnetic interference shielding effectiveness (EMI SE) of the conductive fabrics are evaluated in terms of the content of MWCNT. The test results indicate that the conductive fabrics have optimal tensile strength and optimal bursting strength when composed of 2 wt% MWCNT. Moreover, the conductive fabrics have a stabilized structure as well as the lowest electrical resistivity and an optimal EMI SE when composed of 8 wt% MWCNT. Similarly, 3-layered conductive fabrics also have the maximum EMI SE. The conductive fabrics produced in this study have permanent electrical properties, a light weight, and flexibility. Moreover, their EMI SE reaches the protection level required by standard electronic devices. [ABSTRACT FROM AUTHOR]

The length of multi-walled carbon nanotubes (MWCNT) has an important influence on the properties of polymer/MWCNT composites. This study aims to examine the influence of the length of MWCNT on the mechanical properties, distribution, melting and crystallization behavior, and electromagnetic interference shielding effectiveness (EMI SE) of PP/MWCNT composites. The test results show that MWCNT of a short length contribute to better mechanical properties and have a better dispersion in the matrix. MWCNT also serve as a nucleating agent for PP, thereby increasing the crystallization temperature (T). In particular, short MWCNT provide PP/MWCNT composites with a greater degree of cyrstallinity. The conjunction of 8 wt% long MWCNT in PP/MWCNT composites results in an optimal electrical resistivity of 65.02 Ω-cm, and an average EMI SE of −29.47 dB. The polymer/MWCNT composites have properties that can be adjusted by using different lengths of MWCNT, which is advantageous for application in diverse products. [ABSTRACT FROM AUTHOR]

This study purposes to prepare elastic warp-knitted composite fabric which has multifunctions of shielding electromagnetic interference and emitting far-infrared ray, by altering number of rubber threads cycles. Bamboo charcoal/stainless steel wrap yarns were firstly formed via rotor twister machine, and then fabricated into three kinds of elastic warp-knitted composite fabrics using crochet machine beforehand different number of rubber threads was fed in. The mechanical, comfortability, and functional properties of resulting warp-knitted composite fabrics were evaluated afterward. Result shows that the maximum increase of breaking strength and shear strength of resulting elastic warp-knitted composite fabric was 329 and 176% respectively. The optimal far-infrared emissivity of single-layer warp-knitted composite fabric reached up to 0.9ε. Electromagnetic shielding effectiveness (EMSE) was promoted along with laminated layer and plied angle of composite fabrics. When laminated angle was arranged as 0°/90°/0°/90°/0°, EMSE of warp-knitted composite fabric reached 60 dB at incident frequency of 1988 MHz. The resulting elastic warp-knitted fabrics are applied as health care maternity belts, etc. in the future. [ABSTRACT FROM AUTHOR]

In this study, polyvinyl alcohol (PVA)/graphene nano-sheets (GNs) composites are produced via solution mixing and melt compounding methods, where multi-walled carbon nanotubes (MWCNTs) are added during process. After that, the test results show that PVA/GNs composites composed of 0.25 wt% GNs possess the optimal tensile strength, while the others composed of 2 wt% GNs have a higher thermal stability, electrical conductivity, and electromagnetic interference shielding effectiveness (EMI SE). The addition of MWCNTs provides the PVA/GNs composites with better synergy that can enhance the tensile properties, thermal stability, electrical conductivity, and EMI SE of composites. In comparison to the melt compounding method, the solution mixing method can yield improved properties. [ABSTRACT FROM AUTHOR]

This study proposes multifunctional, fabric-reinforced composites (MFRCs) based on a bionic design, which are prepared by two-step foaming and a combination of different fabric constructs. MFRCs are evaluated in terms of sound absorption, compression resistance, electromagnetic interference shielding effectiveness (EMI SE), and drop impact, thereby examining the effects of fabric structures. The test results indicate that the enhanced composites have superiority functions when combined with carbon fabric in the upper layer and spacer fabric in the lower layer. They have maximum compression resistance, which is 116.9 kPa at a strain of 60%, and their compression strength is increased by 135.9% compared with the control specimen. As a result of the fabric structure on the cell morphology, the maximum resonance peak shifts toward high frequency when using spacer fabric as the intermediate layer. The average sound absorption coefficient is above 0.7 at 1000–4000 Hz. The reinforced composites possessed EMI SE of 50 dB at 2 GHz; an attenuation rate of 99.999% was obtained, suggesting a good practical application value. Furthermore, the cushioning effect of the MFRCs improved significantly, and the maximum dynamic contact force during the impact process was reduced by 57.28% compared with composites without any fabric structure. The resulting MFRCs are expected to be used as sound absorbent security walls, machinery equipment, and packaging for commercial EMI shielding applications in the future. [ABSTRACT FROM AUTHOR]

With the aim of achieving controllable mass production of electrospun nanofiber films, this study proposes and investigates the feasibility of using a custom-made linear electrode- electrospun device to produce conductive graphene (GR)-filled polyvinyl alcohol (PVA) nanofibers. The film morphology and diameter of nanofibers are observed and measured to examine the effects of viscosity and conductivity of the PVA/GR mixtures. Likewise, the influence of the content of graphene on the hydrophilicity, electrical conductivity, electromagnetic interference shielding effectiveness (EMSE), and thermal stability of the PVA/GR nanofiber films is investigated. The test results show that the PVA/GR mixture has greater viscosity and electric conductivity than pure PVA solution and can be electrospun into PVA/GR nanofiber films that have good morphology and diameter distribution. The diameter of the nanofibers is 100 nm and the yield is 2.24 g/h, suggesting that the process qualifies for use in large-scale production. Increasing the content of graphene yields finer nanofibers, a smaller surface contact angle, and higher hydrophilicity of the nanofiber films. The presence of graphene is proven to improve the thermal stability and strengthens the EMSE by 20 dB at 150–1500 MHz. Mass production is proven to be feasible by the test results showing that PVA/GR nanofiber films can be used in the medical hygiene field. [ABSTRACT FROM AUTHOR]

In order to solve the growing problem of electromagnetic radiation and accidental fires due to heat accumulation or electric heating smart clothing, electromagnetic shielding materials with fire resistance are urgently needed. Herein, a polydopamine-assisted polysulfonamide (PSA) nonwoven fabric was designed as a hydrophilic substrate and nano‑silver was employed as a conductive layer. A mixed solution of Fe 3 O 4 with ammonium polyphosphate (APP) was further treated to obtain the surface of microspheres with incombustibility. Interestingly, the micro-nano electromagnetic wave loss gradient enabled the PSA/Ag/Fe 3 O 4 /APP-1(PSA/AFA-1) fabric to exhibit efficient absorption-dominant electromagnetic shielding performance, and the optimized fabric exhibited an EMI SE value of 45.5 dB at X-band (8.2–12.4 GHz) with a shielding efficiency of 99.99 %, which remained stable under multiple twisting and bending. This study opens up a new idea for the preparation of fireproof EMI shielding materials with broad application prospects as well as next-generation multi-purpose garments. [Display omitted] • The average shielding effectiveness (SE) and SSE of the composite fabric could reach as high as 45.5 dB and 167.98 dB(g/cm3). • The micro-nano electromagnetic wave loss gradient constructed by Fe 3 O 4 and Ag nano/mirco coating. • PSA/AFA fabric remained stable under multiple twists and bends. [ABSTRACT FROM AUTHOR]

This study proposes producing polymer composites with a sandwich structure. The surface layers are identical with two alternative interlayers. The surface layers are composites that are composed of polypropylene and multi-walled carbon nanotubes. Interlayers are polyvinyl alcohol (PVA)/MWCNTs composites and PVA/graphene nano-sheets composites. Maleic anhydride grafted polypropylene (PP-g-MA) serves as the coupling agent for the surface layers and the interlayer, in order to create sandwich-structured composites. The polymer composites that are constructed with different combinations are then evaluated for electromagnetic interference shielding effectiveness (EMI SE). The test results show that the incorporation of PP-g-MA reinforces the interfacial adhesion between the sandwich-structured composites, and thereby fortifies their tensile strength. When consisting of a PVA/MWCNTs interlayer, the polymer composites have an optimal electrical conductivity of 5.8 S/cm, and EMI SE of −28.60 dB for 0.0003GHz–1 GHz, −32.89 dB for 1 GHz–2 GHz, and −33.52 dB for 2 GHz–3 GHz. The sandwich-structured polymer composites that have good mechanical properties, good flexibility and high EMI SE can be achieved by using a simple and effective manufacturing method. [ABSTRACT FROM AUTHOR]

[Display omitted] • This layer-by-layer assembly provides a facile strategy in fabricating MXene-coated composite film. • This work proves the huge advantages of nanostructured membranes and MXene to prepare shielding composite film. • The composite film shows excellent electrical conductivity of 71.91 S/cm. • The composite film possesses high EMI SE of 28.82 dB and SSE/t of 12422.41 dB cm2/g. • The composite film exhibits ultrathin, flexible and bending. With the increase of electromagnetic radiation pollution, there is an urgent need to develop lightweight, ultra-thin, and high electromagnetic shielding composite film to eliminate unwanted electromagnetic interference. Herein, based on the layer-by-layer assembly strategy, a simple solution dip coating method was used to achieve the combination of two-dimensional transition metal (MXene) and nanofiber film, thereby constructing a conductive composite film with a unique undulating structure. The silicon-containing hydrophobic layer imparted excellent hydrophobic properties to the composite film while maintained the stability of the sandwich structure. The contact angle (CA) of the composite film with ultra-thin thickness (29um) was 125.49° and the conductivity was as high as 71.91 S/cm. The hydrophobic treatment would not damage the flexibility and mechanical properties of the composite film. In particular, the average shielding effectiveness (SE) and SSE/t could as high as 28.82 dB and 12422.41 dB cm2g−1, due to the layered structure formed by the connection of countless MXene nanosheets is beneficial to promote multiple absorption and reflection. This layer-by-layer assembly strategy provides a facile route in fabricating light-weight, flexible and ultrathin composite film for high-performance electromagnetic shielding, which is of great significance for broadening the practical application of MXene-based conductive materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • The layered structure and sandwich structure film was prepared by bio-inspired strategy. • The composite films shown excellent conductivity (92.68 S/cm) and high tensile strength (93.55 MPa). • The composite films possessed high EMI SE of 32 dB and SSE/t of 4085.92 dB cm2/g. • The multifunctional composite films exhibited ultrathin, flexible, and self-cleaning. With the expanding utilization and development electronic devices, electromagnetic interference (EMI) shielding materials with good flexibility and lightweight have been desired to eliminate the radiation pollution. However, many EMI shielding materials are usually limited in practical application due to the large thickness and poor mechanical properties. Herein, ultra-thin and lightweight conductive composite films with both unique undulating layered structure and sandwich structure were constructed via a simple solution dip-coating method. The PAN@TiO 2 (PT) film as a substrate endowed the Ti 3 C 2 Tx film a certain strength, the polydopamine was decorated on the PT film surface to enhance the combination fastness of the PT film and Ti 3 C 2 Tx, and the Ti 3 C 2 Tx sheets built a conductive network. The conductive composite film (high tensile strength of 93.55 MPa) possessed an average EMI shielding effectiveness (SE) of 32 dB and a specific SE of 4085.92 dB cm2/g owing to their excellent electrical conductivity of 92.68 S/cm. The bio-inspired strategy provides a promising approach in fabricating flexible and ultrathin composite materials for highly efficient EMI shielding applications. Furthermore, this strategy offers a feasible idea for preparing multifunctional films. [ABSTRACT FROM AUTHOR]

• A layer-by-layer self-assembly strategy was used to prepare composite films. • The composite films with unique core-shell and sandwich microstructure for EMI shielding. • In situ polymerization of pyrrole at low temperature had the highest conductivity with a value of 898.72S/m. • The average EMI SE and SSE/t of the composite film reached as high as 23.81dB and 6764.20 dB cm2 g−1. • The composite film was lightweight, flexible. Electromagnetic pollution often interferes with nearby electronic equipment and poses a serious threat to the health of people. There is an urgent need to develop soft and lightweight electromagnetic interference (EMI) shielding materials. In this study, a layer-by-layer self-assembly strategy was used implemented to prepare PAN@Ag@PDA@PPy (PAP@PPy) films with unique core-shell and sandwich composite microstructures for electromagnetic interference (EMI) shielding. Results showed that the conductivity of the composite films was the highest at 898.72 S/m after in situ polymerization of pyrrole at low temperatures. The mechanical properties of the conductive films also increased from the initial 16.81 MPa to 22.54 MPa. The average shielding effectiveness (SE) and SSE/t of the composite films with two layers reached as high as 23.81 dB and 6764.20 dB cm2 g−1, respectively. This performance was caused originates from by the layer structure of the PAN film and multiple internal reflections from the interconnected core-shells and sandwich microstructures in of the PAP@PPy films. Therefore, this work study gave provides a new novel strategy for fabricating conductive polymer composites (CPCs) with high-performance EMI shielding. [ABSTRACT FROM AUTHOR]