High-performance yarns such as aramid fibers are nowadays used to reinforce composite materials due to their advantageous physico-chemical properties and their low weight. They are also resistant to heat and fire. Para-aramid filament yarns (p-AFs) wound on a cylindrical dyeing package have been silvered successfully by means of a newly developed wet-chemical filament yarn metallization process on a laboratory scale. The surface morphology of untreated and silvered p-AF was determined by means of scanning electron microscopy. The chemical structure of the surfaces (contents of carbon, oxygen, nitrogen and silver) was determined by means of energy-dispersive X-ray spectroscopy (EDX). The eliminated and newly formed groups of p-AF before and after silvering were detected by infrared spectroscopy (Fourier transform—attenuated total reflectance). After metallization, the silver layer thickness, the mass-related silver content and washing and rubbing fastness were assessed. Furthermore, textile-physical examinations concerning Young's modulus, elongation at break and electrical conductivity were performed. Subsequently, the electrically conductive p-AFs were integrated in thermoset composite materials reinforced by glass fibers and para-aramid.

The aim of this review is to identify the literature for the scientific work to understand the basics of the conduction mechanism of electrically conductive filament yarns made from extrinsic con-ductive fillers and thermoplastic polymer using melt spinning. In recent years, extrinsic conductive fillers have become very popular due to their electrical conductivity and have received greater research attention. In general, extrinsic conductive fillers are carbon-based conductive materials. These include carbon black (CB), carbon nanotubes (CNT), graphene and graphite. This thematic review mainly focuses on the thermal, mechanical and electrical properties of melt-spun thermoplastic polymers, such as polypropylene, polyamide, poly(ethylene terephthalate), thermoplastic polyurethane, polycarbonate, polyimide, poly(methyl methacrylate and poly(L-lactide)) acid with CB, CNT, graphene and graphite. The structure, shape, size and properties of extrinsic conductive fillers are described in this review. The development of electrically conductive filament yarns from extrinsic conductive fillers using the melt spinning process requires a consideration of the entire process, from pre-treatment, compounding and melt spinning of the extrinsic conductive fillers to the drawing of the electrically conductive filament yarn. In order to achieve better spinnability of the two different components (conductive filler, thermoplastic polymer), an overview of the pretreatment methods of the extrinsic conductive filler and thermoplastic polymers is given. Mixing of inorganic nanomaterials into a polymer matrix involves many challenges, like agglomeration, poor dispersion and scattering of the extrinsic conductive filler within the thermoplastic polymer. Therefore, the most important influencing factors of the melt spinning process are discussed in detail in this review. Depending on the type of polymer (amorphous, crystalline, semi-crystalline), extrinsically conductive fillers can influence the crystallization process in different ways. The textile mechanical and electrical properties of the spun extrinsically conductive yarn will be comprehensively highlighted. Finally, new developments in the field of conductive filament yarns are presented

High-performance textile yarns such as glass filament (GF) yarn will be used as the base material for the development of sensor yarns because glass filament yarns offer both high tensile strengths and moduli of elasticity, as well as high melting temperatures and elongation. A new continuous wet-chemical metallization process has been developed for GF yarns on a laboratory scale to achieve special properties such as electrical conductivity. The aim of the work is to develop a continuous wet-chemical silver plating process for the GF-filament yarn in order to achieve electrical conductivity on the GF-surface. The process was carried out continuously in order to metallize the GF, which is sensitive to the shear force. A homogeneous, completely covered and adhered silver layer on the GF yarn surfaces was obtained by the application of this technology. The surface morphology was been determined by light and scanning electron microscopy to assess the silver layer properties such as structure, homogeneity, and cracking. The chemical structure of the surfaces was analyzed by means of energy dispersive x-ray spectroscopy. For structural analysis, GF yarns were investigated using a Fourier transform infrared spectrometer. The dispersive and polar component of the surface energy of the sized and silvered GF yarn was measured by using a single fiber Tensiometer K100. The silver layer thickness and the silver content were determined after the metallization. Textile physical tests of the tensile strength, elasticity modulus, elongation at break, and yarn fineness of the single GF yarns as well as GF bundle were carried out.

High-performance textile filament yarns such as para-aramid filament yarn (p-AF) will be used as the base material for the development of sensor yarns (SY) because p-AF offer high tensile strengths and moduli of elasticity, as well as high decomposition temperatures and elongation. However, p-AF has an inert or hydrophobic surface, i.e. a lower polar fraction of the total surface energy that does not allow metallization. The aim of this work is the development of a multifunctional sensor yarn consisting of inert and hydrophobic p-AF. By applying new technologies developed at the Institute of Textile Machinery and Textile High Performance Materials Technology, a homogeneous, completely coated first (1st) and second (2nd) silver layer was built on the p-AF filament yarn surface. The first silver layer monitors the damage in the thermoplastic composite globally and the second silver layer locally. Between two silver layers is an insulation layer. Thus, three layers are built on the p-AF surface. The surface morphology has been determined by light and scanning electron microscopy to assess the Ag layer properties such as structure, homogeneity, and cracking. For structural analysis, p-AF were investigated using a Fourier transform infrared spectrometer. The dispersive and polar component of the surface energy of the treated and pretreated p-AF was measured by using a single fiber Tensiometer (Kruess K100. The Ag and insulation layer thickness was determined after coating and metallization. Textile physical tests of the tensile strength, elasticity modulus, elongation at break and filament yarn fineness of the p-AF before and after the silvering were carried out. The length related electrical resistance of the 1st and 2nd silver layer of the p-AF filament yarns was measured by a Multimeter Fluke 45 (Fluka Germany GmbH) with two wire methods.