Showing papers on "Fiber published in 2020"

Recent advancements of plant-based natural fiber–reinforced composites and their applications

Abstract: Demands for reducing energy consumption and environmental impacts are the major driving factors for the development of natural fiber–reinforced composites (NFRCs) in many sectors. Compared with synthesized fiber, natural fiber provides several advantages in terms of biodegradability, light weight, low price, life-cycle superiority, and satisfactory mechanical properties. However, the inherent features of plant-based natural fibers have presented challenges to the development and application of NFRCs, such as variable fiber quality, limited mechanical properties, water absorption, low thermal stability, incompatibility with hydrophobic matrices, and propensity to agglomeration. Substantial research has recently been conducted to address these challenges for improved performance of NFRCs and their applications. This article reviews the recent advancements of plant-based NFRCs, focusing on strategies and breakthroughs in enhancing the NFRCs’ performance, including fiber modification, fiber hybridization, lignocellulosic fillers incorporation, conventional processing techniques, additive manufacturing (3D printing), and new fiber source exploration. The sustainability of plant-based NFRCs using life-cycle assessment and the burgeoning applications of NFRCs with emphasis on the automotive industry are also discussed.

Recent Advances in Fiber Supercapacitors: Materials, Device Configurations, and Applications

Abstract: Fiber supercapacitors (SCs), with their small size and weight, excellent flexibility and deformability, and high capacitance and power density, are recognized as one of the most robust power supplies available for wearable electronics. They can be woven into breathable textiles or integrated into different functional materials to fit curved surfaces for use in day-to-day life. A comprehensive review on recent important development and progress in fiber SCs is provided, with respect to the active electrode materials, device configurations, functions, integrations. Active electrode materials based on different electrochemical mechanisms and intended to improve performance including carbon-based materials, metal oxides, and hybrid composites, are first summarized. The three main types of fiber SCs, namely parallel, twist, and coaxial structures, are then discussed, followed by the exploration of some functions including stretchability and self-healing. Miniaturized integration of fiber SCs to obtain flexible energy fibers and integrated sensing systems is also discussed. Finally, a short conclusion is made, combining with comments on the current challenges and potential solutions in this field.

Understanding the Mechanical and Conductive Properties of Carbon Nanotube Fibers for Smart Electronics

Abstract: The development of fiber-based smart electronics has provoked increasing demand for high-performance and multifunctional fiber materials. Carbon nanotube (CNT) fibers, the 1D macroassembly of CNTs, have extensively been utilized to construct wearable electronics due to their unique integration of high porosity/surface area, desirable mechanical/physical properties, and extraordinary structural flexibility, as well as their novel corrosion/oxidation resistivity. To take full advantage of CNT fibers, it is essential to understand their mechanical and conductive properties. Herein, the recent progress regarding the intrinsic structure-property relationship of CNT fibers, as well as the strategies of enhancing their mechanical and conductive properties are briefly summarized, providing helpful guidance for scouting ideally structured CNT fibers for specific flexible electronic applications.

Mechanical and fracture properties of ultra-high performance geopolymer concrete: Effects of steel fiber and silica fume

Abstract: This study investigates the effects of steel fiber and silica fume on the mechanical and fracture properties of ultra-high performance geopolymer concrete (UHPGC). Four volume fractions of steel fiber (0%, 1%, 2% and 3%) and four contents of silica fume by the mass of total binders (5%, 10%, 20% and 30%) were used. The mechanical and fracture properties evaluated include the compressive, splitting tensile and ultimate flexural strengths, modulus of elasticity, flexural behavior, fracture energy and stress intensity factor. In addition, the correlations among the compressive and splitting tensile strengths, and compressive strength and elastic modulus were studied. The results indicated the increase of steel fiber dosage resulted in the decrease of the workability, but the continuous improvement of mechanical and fracture performance of UHPGC. The empirical equations for predicting elastic modulus of conventional ultra-high performance concrete overestimated the elastic modulus of UHPGC, however some prediction formulas for the splitting tensile strength of PC-based concretes could be applied for UHPGC. Silica fume had a complicated influence on workability and hardened properties of UHPGC, which is strongly dependent on its amount. The inclusion of 10% silica fume induced the increase of the flowability, but the sharp degradation of the mechanical performance, while the specimens with 20% and 30% silica fume possessed the superior mechanical characteristic to that with 5% silica fume. The steel fiber dosage could be decreased without sacrificing the mechanical and fracture performance of UHPGC, via the increase of silica fume content.

High-efficiency super-elastic liquid metal based triboelectric fibers and textiles

Abstract: Fibers that harvest mechanical energy via the triboelectric effect are excellent candidates as power sources for wearable electronics and functional textiles. Thus far however, their fabrication remains complex, and exhibited performances are below the state-of-the-art of 2D planar configurations, making them impractical. Here, we demonstrate the scalable fabrication of micro-structured stretchable triboelectric fibers with efficiencies on par with planar systems. We use the thermal drawing process to fabricate advanced elastomer fibers that combine a micro-textured surface with the integration of several liquid metal electrodes. Such fibers exhibit high electrical outputs regardless of repeated large deformations, and can sustain strains up to 560%. They can also be woven into deformable machine-washable textiles with high electrical outputs up to 490 V, 175 nC. In addition to energy harvesting, we demonstrate self-powered breathing monitoring and gesture sensing capabilities, making this triboelectric fiber platform an exciting avenue for multi-functional wearable systems and smart textiles. Current triboelectric fibers suffer from complex fabrication schemes and relatively poor performance. Here the authors use a highly scalable thermal drawing process to make soft and resilient micro-structured triboelectric fibers and textiles with applications both as sensors and energy harvesters.

Preparation of short CF/GF reinforced PEEK composite filaments and their comprehensive properties evaluation for FDM-3D printing

Abstract: Fused deposition modeling (FDM) has been successfully applied to fabricating short fiber reinforced polymer composites parts. However, due to the intrinsically limited mechanical properties of matrix polymers, there is critical need to develop fiber reinforced high-performance thermoplastic composites for FDM-3D printing to expand engineering applications. In this work, the potential of FDM-3D printing short carbon fiber (CF) and glass fiber (GF) reinforced high-performance PEEK composites has been investigated. Composite filaments with fiber contents of 5 wt%, 10 wt% and 15 wt% were prepared using extrusion process and characterized by micromorphology observation; and thermal properties testing demonstrated its better thermal stability than pure PEEK. The performance evaluation of printed CF/GF-PEEK parts was focused, including mechanical properties, microstructure, surface quality and porosity. The results indicate that the addition of CF/GF to PEEK can significantly enhance the tensile and flexural strength at the cost of ductility. Lower fiber content of 5 wt% is conducive to increasing mechanical properties, improving surface quality and reducing porosity of printed CF/GF-PEEK. GF/PEEK has better interfacial bonding than CF/PEEK due to the different surface treatments on fibers. Furthermore, microstructure observation suggests that fibers aligned along the printing orientation can strengthen the properties, while pores lead to performance degradation of 3D printed CF/GF-PEEK.

Thermal and mechanical properties of bamboo fiber reinforced composites

Abstract: This paper presents the thermal and mechanical properties of bamboo fiber reinforced composite (BFRC) derived from Gigantochloa scortechinii. The bamboo fibers were prepared through chemical treatment by sodium hydroxide (NaOH) followed by physical milling method. The thermal characteristics of the bamboo fiber and its polymer composite were analysed using a thermogravimetric analysis and differential scanning calorimetric. The functional groups and crystallinity of the fiber were analysed with Fourier transform infrared and x-ray diffraction spectroscopy. Meanwhile, the fiber morphology was examined using a scanning electron microscope. The BFRCs with fiber volume fractions ranging from 0 % to 40 % embedded in three thermoset resins (epoxy, polyester, vinyl ester) were subjected to tensile and flexural tests and the fracture pattern was examined. The NaOH concentration of 10 % with soaking duration of 48 h was found to produce a bamboo fiber with the highest ultimate tensile and modulus strength. The tensile and flexural properties of all the BFRCs were found to be directly proportional to the fiber volume fractions. It was found that the bamboo fiber reinforced epoxy composite (BFREC) with 40 % fiber volume fraction exhibited the highest tensile and flexural strength compared to polyester and vinyl ester composites. The method of bamboo fiber composite preparation in this work may serve as a useful guide to produce a strong BFRC for external strengthening of buildings and structures.

Enhanced Piezoelectricity of Electrospun Polyvinylidene Fluoride Fibers for Energy Harvesting.

Abstract: Piezoelectric polymers are promising energy materials for wearable and implantable applications for replacing bulky batteries in small and flexible electronics. Therefore, many research studies are focused on understanding the behavior of polymers at a molecular level and designing new polymer-based generators using polyvinylidene fluoride (PVDF). In this work, we investigated the influence of voltage polarity and ambient relative humidity in electrospinning of PVDF for energy-harvesting applications. A multitechnique approach combining microscopy and spectroscopy was used to study the content of the β-phase and piezoelectric properties of PVDF fibers. We shed new light on β-phase crystallization in electrospun PVDF and showed the enhanced piezoelectric response of the PVDF fiber-based generator produced with the negative voltage polarity at a relative humidity of 60%. Above all, we proved that not only crystallinity but also surface chemistry is crucial for improving piezoelectric performance in PVDF fibers. Controlling relative humidity and voltage polarity increased the d33 piezoelectric coefficient for PVDF fibers by more than three times and allowed us to generate a power density of 0.6 μW·cm-2 from PVDF membranes. This study showed that the electrospinning technique can be used as a single-step process for obtaining a vast spectrum of PVDF fibers exhibiting different physicochemical properties with β-phase crystallinity reaching up to 74%. The humidity and voltage polarity are critical factors in respect of chemistry of the material on piezoelectricity of PVDF fibers, which establishes a novel route to engineer materials for energy-harvesting and sensing applications.

Recent Progress and Perspectives of Thermally Drawn Multimaterial Fiber Electronics

Abstract: Fibers are the building blocks of a broad spectrum of products from textiles to composites, and waveguides to wound dressings. While ubiquitous, the capabilities of fibers have not rapidly increased compared to semiconductor chip technology, for example. Recognizing that fibers lack the composition, geometry, and feature sizes for more functions, exploration of the boundaries of fiber functionality began some years ago. The approach focuses on a particular form of fiber production, thermal-drawing from a preform. This process has been used for producing single material fibers, but by combining metals, insulators, and semiconductors all within a single strand of fiber, an entire world of functionality in fibers has emerged. Fibers with optical, electrical, acoustic, or optoelectronic functionalities can be produced at scale from relatively easy-to-assemble macroscopic preforms. Two significant opportunities now present themselves. First, can one expect that fiber functions escalate in a predictable manner, creating the context for a "Moore's Law" analog in fibers? Second, as fabrics occupy an enormous surface around the body, could fabrics offer a valuable service to augment the human body? Toward answering these questions, the materials, performance, and limitations of thermally drawn fibers in different electronic applications are detailed and their potential in new fields is envisioned.

Evolution of the Lignin Chemical Structure during the Bioethanol Production Process and Its Inhibition to Enzymatic Hydrolysis

Abstract: To illuminate the lignin evolution after hydrogen peroxide presoaking prior to ammonia fiber expansion pretreatment (H-AFEX) pretreatment and enzymatic hydrolysis, ball-milled wood lignins were sep...

Silver Nanowire-Bacterial Cellulose Composite Fiber-Based Sensor for Highly Sensitive Detection of Pressure and Proximity.

Abstract: Fiber-based sensors are desirable to provide an immersive experience for users in the human–computer interface. We report a hierarchically porous silver nanowire-bacterial cellulose fiber that can ...

Effect of natural filler materials on fiber reinforced hybrid polymer composites: An Overview

Abstract: In past decades researchers found many difficulties while providing environmentally supportive materials for product making. Natural fibers possess many advantages over synthetic fibers such as eas...

A review on raw materials, commercial production and properties of lyocell fiber

Abstract: As one of the regenerated cellulosic fibers,viscose fiber has the largest output. However,the wastes produced in the manufacturing process are difficult to eliminate,which restricts the development of viscose fiber. Lyocell fiber is claimed as "green and eco-friendly fiber" with a good application prospect in the 21st century. The preparation of lyocell fiber is based on the cellulosic non-derivative solution system,i.e.,N-methylmorpholine-N-oxide system which is nontoxic and recyclable. Firstly,the demands of dissolving pulp properties for regenerated-cellulosic fiber (RCF),especially for lyocell fiber,were introduced in detail. Next,the whole manufacturing processes including pretreatment,preparation of spinning dope,spinning,posttreatment and efficient solvent recovery technologies were reviewed emphatically. Then,the properties and structural characteristics of lyocell fiber were illustrated. At last,some suggestions were proposed for lyocell fiber development in China.

Effect of Coconut Fiber Length and Content on Properties of High Strength Concrete.

Abstract: Recently, the addition of natural fibers to high strength concrete (HSC) has been of great interest in the field of construction materials. Compared to artificial fibers, natural fibers are cheap and locally available. Among all natural fibers, coconut fibers have the greatest known toughness. In this work, the mechanical properties of coconut fiber reinforced high strength concrete (CFR-HSC) are explored. Silica fume (10% by mass) and super plasticizer (1% by mass) are also added to the CFR-HSC. The influence of 25 mm-, 50 mm-, and 75 mm-long coconut fibers and 0.5%, 1%, 1.5%, and 2% contents by mass is investigated. The microstructure of CFR-HSC is studied using scanning electron microscopy (SEM). The experimental results revealed that CFR-HSC has improved compressive, splitting-tensile, and flexural strengths, and energy absorption and toughness indices compared to HSC. The overall best results are obtained for the CFR-HSC having 50 mm long coconut fibers with 1.5% content by cement mass.