Showing papers on "Fiber published in 2014"

Electrospun Nanofibers: Solving Global Issues

Abstract: Energy and environment will head the list of top global issues facing society for the next 50 years. Nanotechnology is responding to these challenges by designing and fabricating functional nanofibers optimized for energy and environmental applications. The route toward these nano-objects is based primarily on electrospinning: a highly versatile method that allows the fabrication of continuous fibers with diameters down to a few nanometers. The mechanism responsible for the fiber formation mainly includes the Taylor Cone theory and flight-instability theory, which can be predicted theoretically and controlled experimentally. Moreover, the electrospinning has been applied to natural polymers, synthetic polymers, ceramics, and carbon. Fibers with complex architectures, such as ribbon fiber, porous fiber, core-shell fiber, or hollow fiber, can be produced by special electrospinning methods. It is also possible to produce nanofibrous membranes with designed aggregate structure including alignment, patterning, and two-dimensional nanonets. Finally, the brief analysis of nanofibers used for advanced energy and environmental applications in the past decade indicates that their impact has been realized well and is encouraging, and will continually represent a key technology to ensure sustainable energy and preserve our environment for the future.

High‐Mobility Field‐Effect Transistors Fabricated with Macroscopic Aligned Semiconducting Polymers

Abstract: A record high OFET hole mobility, as high as 23.7 cm(2) /Vs, is achieved in macroscopic aligned semiconducting polymers. The high mobility is insensitive to the polymer molecular weight. Polymer chains are aligned along the fiber to facilitate intrachain charge transport.

Polymer/Carbon Nanotube Nano Composite Fibers–A Review

Abstract: Carbon nanotubes (CNTs) are regarded as ideal filler materials for polymeric fiber reinforcement due to their exceptional mechanical properties and 1D cylindrical geometry (nanometer-size diameter and very high aspect ratio). The reported processing conditions and property improvements of CNT reinforced polymeric fiber are summarized in this review. Because of CNT polymer interaction, polymer chains in CNTs’ vicinity (interphase) have been observed to have more compact packing, higher orientation, and better mechanical properties than bulk polymer. Evidences of the existence of interphase polymers in composite fibers, characterizations of their structures, and fiber properties are summarized and discussed. Implications of interphase phenomena on a broader field of fiber and polymer processing to make much stronger materials are now in the early stages of exploration. Beside improvements in tensile properties, the presence of CNTs in polymeric fibers strongly affects other properties, such as thermal stabi...

A Graphene Oxide Membrane with Highly Selective Molecular Separation of Aqueous Organic Solution

Abstract: A graphene oxide (GO) membrane is supported on a ceramic hollow fiber prepared by a vacuum suction method. This GO membrane exhibited excellent water permeation for dimethyl carbonate/water mixtures through a pervaporation process. At 25 °C and 2.6 wt % feed water content, the permeate water content reached 95.2 wt% with a high permeation flux (1702 g m(-2) h(-1)).

Integrated Polymer Solar Cell and Electrochemical Supercapacitor in a Flexible and Stable Fiber Format

Abstract: An all-solid-state, coaxial and self-powered "energy fiber" is demonstrated that simultaneously converts solar energy to electric energy and further stores it. The "energy fiber" is flexible and can be scaled up for the practical application by the well-developed textile technology, and may open a new avenue to future photoelectronics and electronics.

Twisted Aligned Carbon Nanotube/Silicon Composite Fiber Anode for Flexible Wire‐Shaped Lithium‐Ion Battery

Abstract: Twisted, aligned carbon nanotube/silicon composite fibers with remarkable mechanical and electronic properties are designed to develop novel flexible lithium-ion batteries with a high cyclic stability. The core-sheath architecture and the aligned structure of the composite nanotube offer excellent combined properties.

Electrochromic fiber-shaped supercapacitors.

Abstract: An electrochromic fiber-shaped super-capacitor is developed by winding aligned carbon nanotube/polyaniline composite sheets on an elastic fiber. The fiber-shaped supercapacitors demonstrate rapid and reversible chromatic transitions under different working states, which can be directly observed by the naked eye. They are also stretchable and flexible, and are woven into textiles to display designed signals in addition to storing energy.

The hygroscopic behavior of plant fibers: a review

Abstract: Environmental concern has resulted in a renewed interest in bio-based materials. Among them, plant fibers are perceived as an environmentally friendly substitute to glass fibers for the reinforcement of composites, particularly in automotive engineering. Due to their wide availability, low cost, low density, high-specific mechanical properties, and eco-friendly image, they are increasingly being employed as reinforcements in polymer matrix composites. Indeed, their complex microstructure as a composite material makes plant fiber a really interesting and challenging subject to study. Research subjects about such fibers are abundant because there are always some issues to prevent their use at large scale (poor adhesion, variability, low thermal resistance, hydrophilic behavior). The choice of natural fibers rather than glass fibers as filler yields a change of the final properties of the composite. One of the most relevant differences between the two kinds of fiber is their response to humidity. Actually, glass fibers are considered as hydrophobic whereas plant fibers have a pronounced hydrophilic behavior. Composite materials are often submitted to variable climatic conditions during their lifetime, including unsteady hygroscopic conditions. However, in humid conditions, strong hydrophilic behavior of such reinforcing fibers leads to high level of moisture absorption in wet environments. This results in the structural modification of the fibers and an evolution of their mechanical properties together with the composites in which they are fitted in. Thereby, the understanding of these moisture absorption mechanisms as well as the influence of water on the final properties of these fibers and their composites is of great interest to get a better control of such new biomaterials. This is the topic of this review paper.

Lightweight polypropylene/stainless-steel fiber composite foams with low percolation for efficient electromagnetic interference shielding.

Abstract: Lightweight polypropylene/stainless-steel fiber (PP–SSF) composites with 15–35% density reduction were fabricated using foam injection molding. The electrical percolation threshold, through-plane electrical conductivity, and electromagnetic interference (EMI) shielding effectiveness (SE) of the PP–SSF composite foams were characterized and compared against the solid counterparts. With 3 wt % CO2 dissolved in PP as a temporary plasticizer and lubricant, the fiber breakage was significantly decreased during injection molding, and well-dispersed fibers with unprecedentedly large aspect ratios of over 100 were achieved. The percolation threshold was dramatically decreased from 0.85 to 0.21 vol %, accounting for 75% reduction, which is highly superior, compared to 28% reduction of the previous PP–carbon fiber composite foam.1 Unlike the case of carbon fiber,1 SSFs were much longer than the cell size, and the percolation threshold reduction of PP–SSF composite foams was thus primarily governed by the decreased ...

Evolution of disposable bamboo chopsticks into uniform carbon fibers: a smart strategy to fabricate sustainable anodes for Li-ion batteries

Abstract: Future development of mini consumer electronics or large electric vehicles/power grids requires Li-ion batteries (LIBs) with not only an outstanding energy-storage performance but also a minimum cost, and the foremost sustainability. Herein, we put forward a smart strategy to convert used disposable bamboo chopsticks into uniform carbon fibers for anodes of LIBs. Bamboo chopsticks waste is recycled and simply treated by a controllable hydrothermal process performed in alkaline solutions, wherein abundant natural cellulose fibers in bamboo in situ get separated and dispersed spontaneously. After carbonization, the evolved carbon fibers exhibit superior anodic performance to the bulky bamboo carbons counterpart, and competitive electrochemical behavior and cost with commercial graphite. The performance of carbon fibers can be further upgraded by growing nanostructured metal oxides (like MnO2) firmly on each fiber scaffold to form a synergetic core–shell electrode architecture. A high reversible capacity of ∼710 mA h g−1 is maintained without decay up to 300 cycles. Our strategy presents a scalable route to transform chopsticks waste into carbon fibers, offering a very promising way to make sustainable anodes for LIBs and economical multi-functional carbon-based hybrids available for other practical applications.

Controlled Functionalization of Carbonaceous Fibers for Asymmetric Solid-State Micro-Supercapacitors with High Volumetric Energy Density

Abstract: A 1.8 V asymmetric solid-state flexible micro-supercapacitor is designed with one MnO2 -coated reduced graphene oxide/single-walled carbon nanotube (rGO/SWCNT) composite fiber as positive electrode and one nitrogen-doped rGO/SWCNT fiber as negative electrode, which demonstrates ultrahigh volumetric energy density, comparable to some thin-film lithium batteries, along with high power density, long cycle life, and good flexibility.

Fiber synergy in Hybrid Fiber Reinforced Concrete (HyFRC) in flexure and direct shear

Abstract: In most cases, fiber reinforced concrete (FRC) contains only one type of fiber The use of two or more types of fibers in a suitable combination has the potential to improve the mechanical properties of concrete, and result in performance synergy This combining of fibers, often called hybridization, is investigated in this paper under flexure and direct shear Along with a reference plain concrete mix, several single-fiber reinforced concrete mixes and two-fiber reinforced hybrid composite mixes were cast using diverse fiber combinations Two types of macro-steel fibers and a micro-cellulose fiber were examined Flexural and direct shear tests were performed and the results were analyzed to identify synergy, if any, associated with various fiber combinations The paper highlights the influence of load configuration on fiber synergy

Hybrid fiber reinforced polymer composites – a review

Abstract: The polymer matrix composites have been widely used for many applications. These are light in weight and easy for manufacturing. The hybrid fiber reinforced composites have been prepared to enhance the mechanical, thermal, damping properties compared to single-fiber reinforced composites. The fiber reinforced hybrid composites consist of two or more fiber in a matrix system. The different fibers were reinforced with suitable matrix for preparing the hybrid composites using various manufacturing methodology. The hybrid composites are used for many application and replacing wood, wood fiber composites and conventional materials. The mechanical properties (tensile, flexural and impact), dynamic, tribological and water absorption properties of natural fiber reinforced hybrid polymer composites and natural/synthetic fiber reinforced hybrid polymer composites were reported.

Strain-Responsive Polyurethane/PEDOT:PSS Elastomeric Composite Fibers with High Electrical Conductivity

Abstract: It is a challenge to retain the high stretchability of an elastomer when used in polymer composites. Likewise, the high conductivity of organic conductors is typically compromised when used as filler in composite systems. Here, it is possible to achieve elastomeric fiber composites with high electrical conductivity at relatively low loading of the conductor and, more importantly, to attain mechanical properties that are useful in strain-sensing applications. The preparation of homogenous composite formulations from polyurethane (PU) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) that are also processable by fiber wet-spinning techniques are systematically evaluated. With increasing PEDOT:PSS loading in the fiber composites, the Young's modulus increases exponentially and the yield stress increases linearly. A model describing the effects of the reversible and irreversible deformations as a result of the re-arrangement of PEDOT:PSS filler networks within PU and how this relates to the electromechanical properties of the fibers during the tensile and cyclic stretching is presented. Conducting elastomeric fibers based on a composite of polyurethane (PU) and PEDOT:PSS, produced by a wet-spinning method, have high electrical conductivity and stretchability. These fibers can sense large strains by changes in resistance. The PU/PEDOT:PSS fiber is optimized to achieve the best strain sensing. PU/PEDOT:PSS fibers can be produced on a large scale and integrated into conventional textiles by weaving or knitting. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemical Composition of Natural Fibers and its Influence on their Mechanical Properties

Abstract: The conventional composites are replacing such well-established structural materials as steel, iron, and aluminum very fast. The conventional composites are not easily disposable. To overcome the problems of disposability and pollution, the focus is on the fabrication of natural composite materials. The natural composite materials are made from natural fibers and natural resins. Various natural fibers, such as jute, hemp, coir, cotton, and others are used in industry to fabricate natural composite materials. The fibers are load-carrying members in the composites. The main constituents of the fibers are cellulose, hemicelluloses, lignin, pectin, and wax. The composition of fibers depends on the geographic location where the plants are grown up. The peculiarity is the fact that all the fibers have the same constituents, but with different composition, which makes the fibers to behave differently. In this work, the Pearson rank correlation coefficients are found between the composition and properties of the fibers, and the corresponding equations of regression lines are obtained.

Self‐Healable Electrically Conducting Wires for Wearable Microelectronics

Abstract: Electrically conducting wires play a critical role in the advancement of modern electronics and in particular are an important key to the development of next-generation wearable microelectronics. However, the thin conducting wires can easily break during use, and the whole device fails to function as a result. Herein, a new family of high-performance conducting wires that can self-heal after breaking has been developed by wrapping sheets of aligned carbon nanotubes around polymer fibers. The aligned carbon nanotubes offer an effective strategy for the self-healing of the electric conductivity, whereas the polymer fiber recovers its mechanical strength. A self-healable wire-shaped supercapacitor fabricated from a wire electrode of this type maintained a high capacitance after breaking and self-healing.