Solid State Phenomena Vol. 333

Abstract: Most e-textiles are developed for wearable use and thus need to be washable to guarantee a textile typical usability. Yet, there are no e-textile specific wash testing standards and as a result, employed testing protocols vary greatly, resulting in a lack of comparability. To address this issue, an e-textile wash testing protocol modelled after testing methods provided by the standard ISO 6330 (the standard currently most often used as a basis for e-textile wash testing) as well as gentle household washing methods was developed and verified regarding its cleaning capability.

Abstract: The Cluster of Excellence “Centre for Tactile Internet with Human-in-the-Loop (CeTI)” deals with developments and inventions concerning smart devices used in many fields, e.g. industry 4.0, medicine and skill learning. These kind of applications require smart devices, sensors, actors and conductive structures. Textile structures address these applications by meeting requirements such of being flexible, adaptable and wearable. Within this paper, the development of a protective coating for electrically conductive (EC) yarns is captured. These EC yarns are nowadays often used for smart textile applications. One challenge in their application is the integration into textile structures. Often, the handling and use of EC yarns lead on the one hand to damages on the surface of the yarn and on the other hand to reduced electromechanically characteristics. This paper aims to characterize these EC yarns in regard to develop a suitable protective coating based on polypropylene (PP). To achieve this development, an extensive characterization of the EC yarns as well as the protective coating itself is important. The surface free energy (SFE), the topographical and the chemical characteristics are necessary for developing a suitable protective coating. However, the yarns are characterized before and after implementation into the textile structure and furthermore after the coating respectively with the developed finish.

Abstract: In order to avoid environmental pollution by effluents, the incorporation of electrical conductive yarns in a waterproof membrane allows detecting a leak or crack on industrial concrete structure. The membrane is made of composite materials: a glass textile structure equipped with the detector yarns and molded in an epoxy resin. The liquid’s detection and the data’s transmission depend on the yarn’s conductivity variation and its chemical and physical properties. This study aims to develop a water detector monofilament from conductive polymer composites (CPC): an immiscible polymers blend (polyamide 6.6/elastomer) filled with carbon nanotubes (CNT). The addition of elastomer in the CPC yarn is important to withstand the mechanical deformation of the resin structure without breaking. The morphology of the immiscible polymers blend and the localization of the CNT influence the electrical conductivity of the yarn and thus, its property of water detection. Two principles of water detection are investigated with this blend: the short circuit and the absorption. For the short circuit, the presence of liquid is detected when the liquid creates a conductive path between two yarns in parallel. While, the absorption principle is based on the conductivity variation with the yarn’s swelling in contact with water.

Abstract: Electrically conductive textiles for wearable smart devices are in increasing demand [1]. The advantages of flexible fabric structures are combined with electronic functions, such as sensing or actuating, energy harvesting or illuminating, for the design of a multitude of smart textiles. Those functions are often created by applying conductive layers or patterns onto the textile surface with two-phase systems based on conductive filler particles in polymeric binders. However, those systems alter the textile-typical properties regarding haptic, drape, flexibility or weight, depending on the type of conductive particle used, i.e., metal-or carbon-based ones. Generally, electrical conductivity increases with the increase of conductive filler concentration. The relation between the various factors determining the electrical behavior as well as the percolation threshold for some dispersions and in particular the size and shape of the filler particles were previously assessed for planar coatings [2]. In this research work electrically, conductive patterns were printed with dispenser printing technology using such two-phase dispersions based on polyurethane and polyacrylate binders and various metal microparticle flakes. With this application method linear resistance of approx. 25 to 100 Ohm per 100 cm depending on the textile structure could be realized, which was not even significantly reduced by household washing at 40°C or abrasion by Martindale.

Abstract: The internet of things is a key driver for new developments in the fields of medicine, industry 4.0 and gaming. Consequently, the interaction of virtual and real world by smart interconnecting of devices in our everyday life is the basis idea of the Cluster of Excellence "Centre for Tactile Internet with Human-in-the-Loop" (CeTI) at TU Dresden. To enable a user-centric approach in CeTI innovative textile structures, mainly knitted smart gloves, and their functionalization by integration of sensors and sensory yarns are focus of research activities.

Abstract: Adaptive fiber-reinforced plastics (FRP) contain actuators that enable the controlled modification of system states and characteristics. The textile-technical integration of actuators, in particular shape memory alloys, into reinforcing fabrics has increasingly been applied in recent years. The objective is to achieve optimum force transmission from shape memory alloy to FRP, long-term stability of adaptive FRP as well as a maximum degree of deformation. This paper presents the development of actuator networks for adaptive FRP, where two shape memory alloys are integrated into reinforcing fabrics by means of open reed weaving technology. After infusion of the functionalized reinforcing fabrics, the deformation behavior of adaptive FRP was characterized with variable actuator switching frequencies (≥ 1 Hz) or actuator activation times (≤ 1 s).

Abstract: Textile-based Radio Frequency Identification (RFID) tags are widely used in different applications such as sensing, localization, and identification applications. Embroidery is one of the methods in textile-based RFID tag production. The embroidered RFID tags are generally used in the follow-up of textile raw material production and inventory, and laundry of commercial textiles. They capture the transmitted electromagnetic wave and generate a new one with a special coding that includes the required information about the item. Therefore, the fabrication parameters of the embroidered antennas are important in terms of durability, cost, and working performance. The conductivity of an embroidered antenna depends on the conductivity of the thread, stitch density, thread tension, and sewing method of the embroidery. In this study, the effect of stitch density, thread tension, and using conductive yarn as needle (upper) or bobbin (lower) thread for embroidered RFID antennas were examined using a polyester yarn twisted with stainless steel that is plain stitched on cotton fabric. The read range performances of the samples were tested with an integrated circuit (IC) by using an indoor RFID reader. It was seen that the optimised stitch density has a significant impact while it was determining the amount of conductive element due to the length of the yarn. Additionally, using conductive yarn as lower thread gave nearly 50% better results in signal strengths.

Abstract: Nowadays, building insulation must be more and more effective to avoid energy loss. This can result in the lack of ventilation which can cause an increase in the concentration of pollutants in the indoor air, such as Volatile Organic Compounds (VOCs) which are harmful to human health. Different approaches have been proposed to reduce this problem such as ventilation, filtration, depolluting plants, etc. The aim of this study consists of developing functionalized textile substrate allowing the VOCs degradation, ideally into H₂O and CO₂, by the photocatalytic effect under visible light. It is necessary to have photocatalytic activity under visible light for indoor applications as the UV light is filtered by window glasses. To achieve this objective, firstly the samples of woven cotton fabrics are functionalized with the dispersion of silver doped/non-doped TiO₂ in Carboxymethyl Cellulose (CMC) and water by padding process. After that, the treatment sustainability of the functionalized fabric is determined.

Abstract: Nowadays, the heating textiles are used in many fields of applications as medicine or comfort. The heating property for the most part of these textiles was ensured by electrical conductive fiber as metallic yarn thanks to Joule Effect. A challenge for heating textile is to have an electrical conductive fiber which has a temperature self-regulation at the comfort temperature. Thanks to this temperature self-regulation, the heating textile reaches more autonomy. To develop this kind of textile, conductive polymer composite (CPC), which is the combination between an insulating polymer and electrical conductivity nanofillers [1], is made by melt spinning. The temperature self-regulation is provided by the positive temperature coefficient (PTC) effect, which allows switching between an electrical conductivity state and an insulating state when the CPC is close to a transition phase temperature (glass transition temperature or melt temperature). However, when the PTC effect can take place at the melting point, the mechanical properties are not involved. So to maintain the final product an immiscible polymer blend was used: one polymer was the CPC and the second polymer was an insulating polymer with a higher melting point than the target temperature. In fact, the CPC involve the electrical conductivity and the PTC effect, whereas the insulating polymer involves the mechanical properties. However, a high electrical conductivity is necessary to reach the comfort temperature (defined around 42°) by Joule Effect. So to reach this temperature, the coating on a metallic yarn by the conductive immiscible polymer blend was used. The electrical conductivity of this product was improved by the metallic yarn and the self-regulating temperature by the PTC effect of the immiscible polymer blend (figure 1). In this paper the immiscible polymer blend used is a polycaprolactone (PCL) filled with multiwall carbon nanotubes (MWCNT) and a polypropylene (PP). In fact, in a previous paper the co-continuity and the selective localisation of the fillers in the PCL for this blend was studied [2]. The influence of the thickness CPC coating and the influence of the structure of metallic yarn were studied on the electrical conductivity, the Joule Effect and PTC effect.