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Constructions of Textile Fabrics
Published in Robert Mather, John Wilson, Solar Textiles, 2023
After a PV array has been integrated onto a textile fabric, the fabric should retain as far as possible all its original properties, yet enhance PV performance over similar cells that have been deposited on a smooth, homogeneous substrate. There are, however, major differences between the mechanical properties of textile fabrics and those of PV cells. As shown in Chapter 2, the PV array will consist of thin electrically conductive layers and thin semiconductor layers. Even though these layers will be very thin (of the order of micrometres), they will still be inherently rigid and quite brittle, yet they must withstand stretching, bending and twisting of the textile fabric. As a consequence, there are risks of cracking and delamination of the layers. The activity of the PV cells will be impaired, and the conductivities of the conducting layers will be severely reduced. In addition, delamination is more likely to occur if there is little chemical compatibility between the yarn surfaces and the layers adjacent to these surfaces. The requirement for continuity in the deposited layers thus places demands on the dimensional stability of the fabric structure, and in turn the textile fabric can make heavy demands on the durability of the deposited layers. In practice, therefore, there have to be compromises in PV cell design.
Manufacture of Composites with Flexible Towpregs
Published in R. Alagirusamy, Flexible Towpregs and Their Thermoplastic Composites, 2022
V. Balakumaran, R. Alagirusamy, Dinesh Kalyanasundaram
Flexible towpregs for manufacturing TPC refers to the structural hybridized textile preforms (mixing matrix and reinforcement in the fibrous form), which are in a semi-impregnated state. A semi-impregnated state refers to the thermoplastic resin present in the vicinity of the reinforcement fibers without wetting (fiber and matrix separated). Hybrid yarn, hybrid fabric, and powder-impregnated towpregs are different forms of flexible prepregs discussed in earlier chapters. One of the hybrid yarns is a commingled yarn, where the matrix thermoplastic is mixed with the reinforcement fiber in the fibrous form, at the yarn level (Alagirusamy et al. 2010). The mixing at the yarn level is achieved by spinning, wrapping, braiding, and air-jet texturing methods (Alagirusamy et al. 2010). The hybrid fabric is a co-woven or flat/circular braided or knitted textile fabric structure (Alagirusamy et al. 2010). The thermoplastic matrix yarn and reinforcement yarn are used in different combinations to produce these hybrid fabric textile preforms. In powder impregnated tows, the thermoplastic matrix in the form of powder is deposited on the reinforcement fiber. The powder matrix is coated on the reinforcement yarn by dry and wet powder coating methods, followed by sintering of the coated powder to fuse it with the reinforcement fiber (Iyer and Drzal 1990; Ho et al. 2011). Complete wetting of the reinforcement fibers does not happen during the sintering process (Iyer and Drzal 1990). In all forms of the flexible towpregs, the wetting of the reinforcement fibers does not occur.
Textiles for Firefighting Protective Clothing
Published in Guowen Song, Faming Wang, Firefighters’ Clothing and Equipment, 2018
Abu Shaid, Lijing Wang, Rajiv Padhye
Ripstop weave is a widely used woven fabric structure in technical textile industry. It is designed to stop the ripping. Extra high strength yarn is weaved in regular interval within the normal base fabric to provide resistance to spreading of tear. The definition of ripstop weave is given as “very fine woven fabric, often nylon, with coarse, strong warp and filling yarns spaced at intervals so that tears will not spread. The same effect can be achieved by weaving two or three of the fine yarns together at intervals” (Wingate, 1979, p. 513). It is suitable for technical textiles that required resistance to tear. In 2005, Du Pont patented weave fabric structure specially designed for FPC with ripstop yarn component where the ripstop yarn has at least 20% more tensile strength than the body yarn (Zhu & Young, 2005). Nowadays, many manufacturers use ripstop construction for fabric intended as an outer layer fabric of FPC.
A generalised geometric model for the determination of shear angle during the bias-extension test
Published in The Journal of The Textile Institute, 2022
In Figure 9b, the mean load vs. mean shear angle (determined by the proposed model) graphs of different fabric types are given for S10 and S20 samples. It is observed that the shear angle of the S10 samples increases rapidly with a small change in load, initially. Since the twill fabric structure has longer yarn floatings, the amount of shear is higher in twill fabrics especially in the early stages of the test. Then, the change of the shear angle begins to decrease for all fabric types, because the yarn begins to lock up and resist shear. As noted in the literature (Prodromou & Chen, 1997), the loads rise sharply as the fabric approaches the locking angle. At the early stages of the bias-extension test, the increase of load is slow for the S20 sample compared with S10. Especially, there is no considerable increase at the load of 2/2 twill fabric up to 25–30 mm displacement. On the other hand, the shear angle increases rapidly at the beginning of the test, and then the increase of shear angle between two consecutive displacements decreases. Decrease of the shear angle increases load value due to the shear resistance of the fabric. An evident deformation occurred in the structure of the 2/2 twill fabric samples after 50 mm displacement: yarns separated from the edges of the samples. As a result of this deformation, a decrease in the load value was observed.
Interaction effects of washing and abrasion on thermal protective performance of flame-retardant fabrics
Published in International Journal of Occupational Safety and Ergonomics, 2021
Lijun Wang, Jiazhen He, Yehu Lu, Shumin Jiang, Min Wang
With certain cycles of washing, TPP and RPP values of the fabric were significantly higher or at least remained at the same level compared to the original state. One explanation for this might be that the outer shell was made of aramid fibers, which had intrinsic and permanent flame retardancy. Unlike the flame-retardant finishing that is easily destroyed by washing, the flame retardants of the aramid fabric were more influenced by the fabric structure than by the operating environment such as washing treatments. Another possible explanation is that the structure of the fabric after washing became loose and fuzzing occurred on the surface as well, increasing the ability to hold still air within the fabric and improving the TPP and RPP values. The impact of heat exposure type should also be considered to compare the effect of washing. In this study, the RPP value after 12 washing cycles was still significantly higher than that of untreated fabric, whereas the TPP value after 12 washing cycles was pretty close to that of untreated fabric, and further washing might make the TPP value lower than the initial value. To extend the lifetime of firefighters' protective clothing, reducing washing cycles might be an effective option.
Wearable high-performance meander ring dipole antenna for electronic-textile applications
Published in The Journal of The Textile Institute, 2020
Bahareh Moradi, Raul Fernández-García, Ignacio Gil
The resonance method based on a split post dielectric resonator (SPDR) measurement was carried out to determine the substrate dielectric constant and loss tangent of felt substrate. The felt fabric was characterized with h = 0.7 mm thickness, dielectric constant ɛr = 1.2, and loss tangent tan δ = 0.0013. The fabric structure was a non-woven structure with a 100% polyester (PES) composition. The fabric was selected due to its durability, resistance and low intrinsic losses. These types of textile substrates are resistant to tearing and humidity and they offer some key advantages, including durability, chemical moisture resistance, and heat stability. The weight is 211 g/m2 (PCE-BS 300 balance) and the structure corresponds to a double-sided needle punching. For antenna fabrication, the embroidery machine Singer Futura XL550 has been used. The selected conductive yarn corresponds to a commercial Shieldex 117/17 dtex 2-ply and it is composed by 99% pure silver-plated nylon yarn 140/17 dtex with a linear resistance <30 Ω/cm.