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Flexible supercapacitors
Published in Ling Bing Kong, Nanomaterials for Supercapacitors, 2017
Ramaraju Bendi, Vipin Kumar, Pooi See Lee
In addition, fibers can be mixed to obtain hybrid fabrics. Woven fabric exhibited promising mechanical strength and stiffness, as well as excellent flexibility. However, carbonaceous fibers cannot meet the requirements to achieve high energy density and specific capacitance. Therefore, they are practicallyincorporated with pseudocapacitive materials, i.e., metal oxides, like RuO2 [39], NiO [40] and MnO2 [41, 42] or conducting polymers [43–46]. Excellent capacitive energy storage properties of pseudocapacitive components have been developed with CFs that have high electrical conductivity and mechanical flexibility [47, 48]. Growth of pseudocapacitive materials on well conductive carbon substrates can not only facilitate the diffusion of electrolyte ions but also can improve the transport of electrons, thus enhancing the electrochemical properties [49–54]. Metal oxide or conducting polymers on CFs core-shell fibers could be fabricated by using electrodeposition processes, as schematically demonstrated in Fig. 6.6.
Materials
Published in Ever J. Barbero, Introduction to Composite Materials Design, 2017
Besides popular biaxial woven fabrics such as plain weave, twill, and satin, other woven fabrics with unique features exist. If reinforcement is desired in only one direction, but maintaining the ease of handling and drape properties of woven fabrics, the solution is called uniaxial woven fabric (Figure 2.4). In this case, normal yarns are used along the warp direction but only thin yarns that can be made from another low cost, low quality material are used along the fill direction, their role being to keep the warp yarns together. In this way the mechanical reinforcing effect is obtained only along one axis (the warp axis). By contrast, if a multiaxial reinforcement effect is desired (including bias directions), the solution is a triaxial woven fabric (Figure 2.4), which is obtained by interlacing three sets of yarns at different angles. Quasi-isotropic material properties can be obtained in this way, but this also implies special weaving technologies that impact the product cost.
Reinforcements and Matrices for Polymer Matrix Composites
Published in Manoj Kumar Buragohain, Composite Structures, 2017
Woven fabrics are made by weaving yarns, tows, or rovings on a loom. The fibers are placed in the warp and weft directions, and interlaced in different ways to make different weave styles. Warp is the 0° direction, that is, parallel to the length direction of the roll, whereas, weft, also known as fill, is the 90° direction. Relative amounts of fibers in the warp and weft directions depend on the type of weave style, and in general, equal or nearly equal amounts fibers are placed in both the directions. These fabrics are called as balanced fabrics. In certain cases, most of the fibers are placed in the warp direction only and these fibers are held in position by very fine threads in the weft directions. These fabrics, known as unidirectional fabrics, possess exceptionally high strength and stiffness properties in the warp direction but very low properties in the weft direction.
A computer software developed for designing woven patterns and generating machine readable files for sampling looms
Published in The Journal of The Textile Institute, 2023
Woven fabrics are textile structures produced on a loom by interlacing at least two sets of yarns (warp and weft) at right angles to one another. The distribution of interlacement is called as weave design or pattern. Graphical representations of the weaves can be shown by a grid in which columns represent warp and rows represent weft. Each square represents the intersection of a warp yarn and a weft yarn. A mark in a square indicates that end goes over pick while a blank square indicates that the pick is over the end. In the case of color effect presentation, the squares are painted with the color of warp or weft yarns depending on the interlacement of yarns. Conventionally designers draw out the pattern on a squared paper. However, while drawing patterns on paper especially with different color effects, plenty of time is wasted even for a pattern that outlooks for only a piece of fabric. Therefore, Computer Aided Design (CAD) tool has become an essential part of the development and sampling process of the woven fabric design. CAD systems allow designers to display and modify patterns very quickly before weaving the fabric (Cristian & Piroi, 2016; Hu, 2004; Behera et al., 2012; Mathur & Seyam, 2011).
Optimisation of bending and shear rigidities of woven fabrics using hybrid DOE-NSGA-II approach
Published in The Journal of The Textile Institute, 2023
Md Samsu Alam, Abhijit Majumdar, Anindya Ghosh
Woven fabric, a unique material that is flexible yet strong, is manufactured by interlacement of two sets of yarns usually at right angle to each other. In many application areas like ballistic vests, seat belts, woven geotextiles, sports clothing etc., good mechanical performance is often a critical prerequisite along with desired bending and shear rigidities (Lomov et al., 2000). Lower bending rigidity of fabric facilitates better drapeability and fit, whereas higher shear rigidity ensures better dimensional stability. The basic design components of a woven fabric are fibre type in yarn (natural or synthetic), yarn count (coarseness or fineness), fabric sett (ends per inch or EPI × picks per inch or PPI) and weave (interlacement pattern). Any change in fibre or yarn properties or weave in fabric is expected to alter the resultant mechanical and functional properties of fabrics. Woven fabrics are subjected to various complex deformations like tensile, bending, shear and compression during their use (Hu & Lo, 2002; Inogamdjanov et al., 2020). Among these, bending and shear deformations, in low stress region, are very important for many applications including clothing (Tadesse et al., 2019). Bending and shear rigidities are the resistances of a fabric against the bending moment and shear force, respectively. Therefore, bending and shear behaviours of woven fabrics have captured the curiosity of research fraternity.
Variability of the penetration of particles through facemasks
Published in Aerosol Science and Technology, 2022
Buddhi Pushpawela, Stavros Amanatidis, Yuanlong Huang, Richard C. Flagan
Owing to the shortage of N95 and quality medical masks around the world, many countries recommend that people wear cloth masks to limit the spread of COVID-19. Most cloth masks employ fabrics in which threads are woven or knitted into regular arrays. A key parameter used to characterize woven fabrics is the thread count, the number of threads per square inch, including the length warp and width weft threads. Threads are made by twisting much smaller fibers together. For some fabrics, the fibers are comparable in size to the fibers in the non-woven filters; as such, if they were not twisted into much larger threads, they might be more effective at capturing particles by all three non-charge mechanisms, i.e., diffusion, impaction, and interception. The weaving process may further leave a pattern of holes through which air may leak without being filtered. Most of the cloth masks did not show significant size dependence in particle penetration, similar to that in Figure 2b. Leakage through the open space in the weave may be responsible for this flat response.