Forschungspublikationen

3 Ergebnisse
08.09.2023

Mit einem Sustainability-Assessment zur nachhaltigen Unternehmensstrategie

Nachhaltigkeit Technische Textilien

Zusammenfassung

Die Textilindustrie gilt im Sinne der Nachhaltigkeit auf europäischer Ebene als Risikobranche. Warum das eine besondere Herausforderung ist und wie ein systematischer Ansatz zur nachhaltigen Transformation von Unternehmen aussehen kann, erfahren Sie in diesem Artikel.

Die Textilindustrie ist bekannt für ihre Innovationen und Ideen, die weit über die traditionellen Anwendungen von Bekleidung und einfachen Stoffen hinausgehen. Einige Beispiele sind der Einsatz von Glas- oder Carbonfasern zum Ersatz von Stahlbewehrungen in Betonbauteilen, künstliche Herzklappen aus Textilien oder Wasserstofftanks aus Carbonfasern. Allerdings steht die Textilindustrie vor großen Herausforderungen in Bezug auf Nachhaltigkeit. Sie ist weltweit eine der Branchen mit den höchsten Umweltbelastungen und hat auch erhebliche soziale Auswirkungen auf die Arbeitskräfte in der Lieferkette, die häufig auf Baumwollfeldern in Ländern wie China, Indien oder Pakistan beginnt. Hier ist ein systematischer Ansatz zur Nachhaltigkeitsbewertung erforderlich. Das Ergebnis der Nachhaltigkeitsbewertung bildet den Status Quo ab, kann als Benchmark im Vergleich mit anderen Unternehmen der Branche verwendet werden und bietet einen optimalen Ausgangspunkt für die Integration von Nachhaltigkeit in die Unternehmensstrategie.

Bericht

Einleitung

Aachen/München: Die Textilindustrie ist bekannt für ihre Innovationen und Ideen, die weit über die traditionellen Anwendungen von Bekleidung und einfachen Stoffen hinausgehen. Einige Beispiele sind der Einsatz von Glas- oder Carbonfasern zum Ersatz von Stahlbewehrungen in Betonbauteilen, künstliche Herzklappen aus Textilien oder Wasserstofftanks aus Carbonfasern.

Allerdings steht die Textilindustrie vor großen Herausforderungen in Bezug auf Nachhaltigkeit. Sie ist weltweit eine der Branchen mit den höchsten Umweltbelastungen und hat auch erhebliche soziale Auswirkungen auf die Arbeitskräfte in der Lieferkette, die häufig auf Baumwollfeldern in Ländern wie China, Indien oder Pakistan beginnt. Auch die weiterverarbeitenden Prozesse innerhalb der Wertschöpfungskette bergen die Gefahr unzureichender Umweltschutzmaßnahmen und der Missachtung international geltender Menschenrechte. Eine nachhaltige Textilindustrie hingegen setzt sich gezielt und insbesondere für den Einsatz von umweltfreundlichen Materialien, faire Arbeitsbedingungen und die Reduzierung des Energie- und Wasserverbrauchs ein. „Die EU verweist in ihrer neuen Sustainable Product Initiative nicht umsonst verstärkt auf ein hohes Maß an Umweltschutz und notwendige Verbesserungen der Umweltqualität. Wir müssen an den wichtigen gesellschaftlichen Herausforderungen forschen und neue Technologien schnell in die Umsetzung bringen“, so Prof. Thomas Gries vom Institut für Textiltechnik (ITA) der RWTH Aachen University.
 

Systematischer Ansatz zur Nachhaltigkeitsbewertung

Auf Unternehmensebene fängt die Transformation mit der Erfassung der notwenigen Daten (Indikatoren) und der der daraus resultierenden Messbarkeit der eigenen Nachhaltigkeitsleistung an. Die TÜV SÜD Industrie Service GmbH hat dazu eine Methodik entwickelt, die in Zusammenarbeit mit dem ITA für die Textilindustrie adaptiert und optimiert wurde: die Nachhaltigkeitsbewertung orientiert sich an den 17 Sustainable Development Goals (SDG) der Vereinten Nationen. Auf der Grundlage verschiedener Indikatoren, die durch Branchen- und Ländervergleiche gewichtet werden, wird die Nachhaltigkeitsleistung des Unternehmens objektiv, unabhängig und transparent beurteilt. „Mit unserer Nachhaltigkeitsbewertung ermöglichen wir allen relevanten Akteuren der Wertschöpfungskette Klarheit über den Ist-Zustand der unternehmensspezifischen Nachhaltigkeit zu erlangen, die wesentlichen Nachhaltigkeitsrisiken zu identifizieren und mit den daraus abgeleiteten Verbesserungsmaßnahmen einen wesentlichen Schritt in Richtung eines Nachhaltigkeitsmanagementsystems zu gehen“, so Lucas Wagner von der TÜV SÜD Industrie Service GmbH. Dieser Ansatz umfasst die gesamte Unternehmensstrategie und ist auch für andere Branchen einsetzbar.
 

Integration von Nachhaltigkeit in die Unternehmensstrategie

Das Ergebnis der Nachhaltigkeitsbewertung bildet den Status Quo ab, kann als Benchmark im Vergleich mit anderen Unternehmen der Branche verwendet werden und bietet einen optimalen Ausgangspunkt für die Integration von Nachhaltigkeit in die Unternehmensstrategie. Die objektive Bewertung bietet zunächst die Möglichkeit, notwendige Schwerpunkte für die Transformation hin zu einem nachhaltigen Unternehmen zu identifizieren. Zusammen mit externen Experten, z. B. aus der Forschung, werden Potentiale identifiziert und konkrete Umsetzungsmaßnahmen abgeleitet. „Das Vorgehen bietet einen holistischen Ansatz, um die nachhaltige Transformation zu einem Kern der Unternehmensstrategie zu machen. Die Wirtschaftlichkeit bildet dabei eine wichtige Säule“, so Prof. Gries. Darüber hinaus bietet die Nachhaltigkeitsbewertung durch die TÜV SÜD Industrie Service GmbH eine ausgezeichnete Ausgangslage, um die Anforderungen der CSRD, also der „Corporate Sustainability Reporting Directive“ zu erfüllen. So wird Nachhaltigkeit zu einem planbaren Erfolgsfaktor für Unternehmen.

Bildunterschriften:

Abbildung 1: 17 Ziele für nachhaltige Entwicklung (SDG) der Vereinten Nationen (Quelle: Vereinte Nationen)

Abbildung 2: Methodischer Ansatz für die Nachhaltigkeitsbewertung eines Unternehmens (Quelle: TÜV SÜD Industrie Service GmbH)

Abbildung 3: Wesentlichkeitsanalyse und Strategieentwicklung (Quelle: TÜV SÜD Industrie Service GmbH)

AutorInnen: Pohlmeyer, Florian1 Wagner, Lucas2 Möbitz, Christian1 Gries, Thomas1

1: Institut für Textiltechnik der RWTH Aachen University, Otto-Blumenthal-Str. 1, 52074 Aachen

2: TÜV SÜD Industrie Service GmbH, Westendstraße 199, 80686 München

More entries from ITA Institut für Textiltechnik der RWTH Aachen University

20.06.2023

Development of heavy tows from recycled carbon fibers for low-cost and high performance thermoset composites (rCF heavy tows)

Rohstoffe Fasern Garne Composites Textilmaschinenbau Recycling Nachhaltigkeit Kreislaufwirtschaft Technische Textilien

Zusammenfassung

Within the framework of the IGF research project (21612 BR), the entire process chain for the industrial production of novel twist-free rCF heavy tows was developed at ITM. In particular, a novel technology for the production of rCF heavy tows based on recycled carbon (rCF ≥ 90 vol.%) and hot melt adhesive fibers (< 10 vol.%) was designed, constructed and successfully implemented. This includes fiber preparation, the carding process for card sliver formation, the stretching process for drawn sliver formation, and the final fabrication of the rCF heavy tows from rCF and hot melt adhesive fibers in a newly developed test set-up. The suitability of the developed technology is demonstrated by the implementation of rCF heavy tows with different rCF types, fiber lengths and fiber volume contents and a demonstrator. The developed rCF heavy tows with finenesses between 3000-7000 tex and their further processability into textile semi-finished products were successfully demonstrated. The developed rCF Heavy Tows and composites based on them exhibit a maximum composite tensile strength and a maximum Young’s modulus of 1158±72 MPa and 80±5.7 GPa, respectively. The rCF Heavy Tows are thus applicable for low-cost thermoset composites with high performance and complex geometry. Thus, the developed rCF Heavy Tows offer a very high innovation and market potential in the fields of materials and materials, lightweight construction, environmental and sustainability research, and resource efficiency. This opens up the opportunity for SMEs in the textile industry to develop new products and technologies for the fiber composite market and to establish themselves as suppliers for the automotive, mechanical engineering and aerospace, medical and sports equipment industries.

Bericht

Introduction, problem definition and aim of the project

Carbon fiber-reinforced plastics (CFRP) are increasingly used in lightweight applications due to their high stiffness and strength as well as low density, especially in aerospace, transportation, wind energy, sports equipment or construction. Global demand of CFRP is predicted to increase to 197,000 t/a by 2024, almost tripling compared to 2011. This shows an urgent need for solutions to recycle the high quality carbon fiber (rCF) in terms of the circular economy. This is necessary not only due to strict legal regulations, but also for ecological and economic reasons. In recent years, numerous research institutes and companies developed solutions for the reuse of rCF in the fields of nonwovens, injection molding or as hybrid yarns. However, the majority of these works involve the use of rCF in combination with thermoplastic fibers for thermoplastic composites. In the field of rCF-based thermoset CFRP, mainly rCF nonwovens made of 100% rCF have been so far developed. Since the fibers in the nonwovens mostly have a limited length and a low orientation and process-related additional high fiber damage occurs, with these materials only maximum 30% of the composite characteristic values of CFRP components made of carbon filament yarns can be so far achieved.

Currently, the matrix systems used in the field of high mechanical loaded CFRPs are predominantly thermoset. Such components exhibit high dimensional stability, high stiffness and strength as well as are suitable for the implementation of complex component geometries due to low-viscosity matrix systems. However, primary carbon filament yarns are particularly used for these components due to the insufficient properties of rCF. In addition to low sustainability, the utilization of these filament yarns result in at least 200 % higher cost. The production of primary carbon filament yarn requires a high-energy demand of about 230 MJ/kg with a CO2 emission equivalent to 20 kg CO2/kg CF. Here, a significant improvement of the CO2 balance is required to make a substantial contribution to the envisaged climate protection goals of the Federal Republic of Germany and the EU. For this reason, the focus of the project work is the development of novel, sustainable rCF heavy tows made of recycled carbon fibers (rCF) and associated manufacturing technologies for the implementation of cost-effective thermoset composites with high mechanical performance.

Acknowledgments

The IGF project 21612 BR of the Research Association Forschungskuratorium Textil e.V. was funded by the Federal Ministry of Economics and Climate Protection (BMWK) via the AiF within the framework of the program for the promotion of joint industrial research and development (IGF) on the basis of a resolution of the German Bundestag. We would like to thank the above-mentioned institutions for providing the financial resources.

AutorInnen: Mahmud Hossain, Anwar Abdkader und Chokri Cherif

Technische Universität Dresden
Fakultät Maschinenwesen
Institut für Textilmaschinen und Textile Hochleistungswerkstofftechnik (ITM)
01062 Dresden

https://tu-dresden.de/mw/itm

rCF fiber yarn Composite textile machine

More entries from TU Dresden, Institut für Textilmaschinen und Textile Hochleistungswerkstofftechnik ITM

16.01.2023

Increased performance and sustainability through the use of profiled textile reinforcements for concrete applications

Fasern Garne Gestricke & Gewirke Textilmaschinenbau Nachhaltigkeit Technische Textilien

Zusammenfassung

At the ITM of the TU Dresden, new, bond optimized reinforcement yarns were developed on the basis of braiding and forming technology, which can transmit up to 500 % higher bond forces in concrete than yarns without profile. The profiled rovings and braided yarns show at a bond length of only 50 mm a full anchoring. With the forming technology developed at the ITM, profiled rovings could be manufactured which, due to the patented tetrahedral geometry, can almost completely exploit the tensile potential of the carbon fibers. In the course of developing the braiding yarns, a new vario braiding structure was developed, with nearly eliminated structural elongation under load. This made it possible to manufacture profiled reinforcement yarns with very high tensile properties, which is a basic requirement for use in concrete. In addition, the multiaxial warp knitting technology has been further developed in such a way that the new bond optimized reinforcement yarns (profiled rovings and braiding yarns) can be processed without damage into profiled, grid-like textile reinforcements. This results in a significantly higher material efficiency of the textile reinforcement, so that previous necessary disproportionate oversizing and large overlapping lengths can be significantly reduced. This is of enormous importance, especially in view of the energy-intensive production of carbon fibers and consequently for the sustainability goal of the future-oriented carbon concrete technology, in order to make concrete constructions of the future resource saving and sustainable.

The project results achieved also represent a significant contribution to the production of extremely resilient textile-reinforced concrete structures with significantly improves bond properties, arising new prospects in the construction industry for component production in the field of renovation and new construction.

Bericht

Abstract
Building in a resource-saving way and still exploiting a high performance potential, is that even possible? At the Institute for Textile Machinery and High Performance Material Technology (ITM) at the TU Dresden, such composite optimized profiled textile reinforcements for concrete applications and the related manufacturing technology were developed as part of the research project IGF 21375 BR. On the basis of braiding and forming technology, a new generation of profiled reinforcement yarns was developed with the help of simulation-based investigations. Like ribbed steel reinforcements, these profiled yarns have a very high bond with the concrete matrix, but despite the profiling they almost fully exploit the performance potential of the carbon fibers in terms of tensile properties. In this way, the bond length required for complete force transmission between the textile reinforcement and the concrete can be reduced to just a few centimeters, and up to 80 % of the component-dependent oversizing of the textile reinforcement can be saved. The further development of the multiaxial warp knitting technology for the requirement-based and fiber-friendly processing of the profiled yarns into grid-like reinforcement structures enables the production of profiled textile reinforcement structures with the highest bond properties for use in carbon-reinforced concrete components with maximum material and resource efficiency.

Initial situation and problem definition
As is generally known, climate change is the greatest challenge of the 21st century, which can only be successfully overcome by consistently saving resources and CO2 emissions. Since the construction industry, with a share of approx. 38 % of global CO2 emissions, has made a significant contribution to global warming to date, in particular due to the enormous cement consumption [1], a change to more energy and resource efficiency as well as a growing awareness of sustainability is absolutely necessary. In the course of this, a resource-efficient carbon concrete, consisting of a corrosion-resistant textile reinforcement in combination with a significantly reduced concrete cover, is established in the construction industry as a convincing alternative to conventional steel reinforced concrete [2,3].

Due to the high load-bearing capacity of the textile reinforcement with the smaller concrete cross-sections required, the bond between the textile and the concrete is extremely important. So far, R&D has focused on the development of impregnations and impregnation systems for improved material bond with the concrete matrix [4]. However, only small forces with a shear flow of about 5 - 40 N/mm can be transferred, an efficient utilization of the textile reinforcement is not possible. Solutions with profiling of the yarn surface promise significant improvements in the transmission of bond forces [5]. Therefore, new technologies for the continuous and reproducible production of profiled textile high-performance fiber yarns and their further processing into reinforcement structures were developed within a research project at the ITM of the TU Dresden. These innovative, profiled reinforcements are characterized by their ability to transmit significantly higher bond forces in concrete [6,7]. In particular, this was realized by a form-fitting effect between the textile and the concrete, that meets the specific requirements of a stiff and symmetrical surface profile of the reinforcement yarns in order to guarantee a constant and high force transmission. To generate the yarn profiling, solutions based on braiding technology and forming processes were developed and implemented with the help of simulation-supported studies. The premises were a permanently stable textile structure and a profile with a symmetrical structure. The realization of grid-like reinforcement structures, consisting of the profiled reinforcement yarns, was carried out using the multiaxial warp knitting technology. This was developed further on a modular basis with regard to the existing processes (yarn feeding, weft yarn insertion, knitting process, impregnation and winding) in accordance with the necessary adaptation measures for the fiber-friendly and requirement-based further processing of the profiled reinforcement yarns into grid-like structures.

Development of the innovative profiled reinforcement yarns
For the development of bond optimized profiled reinforcement yarns for concrete applications, a simulation-supported yarn development was carried out on the basis of braiding and forming technology. In particular, the main challenge was to realize profiled yarns with minimal structural elongation, so that, an initial force transmission of the textile reinforcement is possible and the concrete crack widths are minimized [3] if the concrete matrix fails at approx. 0.2 % elongation. For this purpose, a new type of varying braiding structure was developed. Moreover the braiding technology was further developed to enable a low-undulation and pre-stabilization of the braiding yarn structure during the braiding process, yet still ensuring further textile processing. As a result, it is now possible to implement novel vario braiding yarns as well as conventional packing braided yarns, consisting of carbon fibers with nearly eliminated structural elongation, minimal fiber damage and the required pre-stabilization of the yarn structure (see Table 1).

...

Performance potential of the new profiled reinforcement yarns
The newly developed profiled reinforcement yarns are characterized by nearly unchanged tensile properties, yet up to 500 % higher bond properties compared to carbon rovings without profile or rovings extracted from reference textiles (see Figure 1). In addition, they do not show any noticeable structural elongation, so that an initial force transmission is possible without additional crack opening after the failure of the concrete matrix. However, an increase in bond strength of more than 500 % from approx. 20 N/mm of the carbon rovings without a profile to over 100 N/mm of the profiled reinforcement yarns was achieved, which is accompanied by a significant increase in material efficiency (see Figure 1). The vario braiding yarns in particular are characterized by very high bond stiffness, which is of particular interest for an initial force transmission. The packing braiding yarns and the profiled rovings with tetrahedral geometry have almost the same bond properties. The bond stiffness is marginally lower compared to the vario braiding yarns, whereas their production is more productive than the vario braiding yarns.

Development of the multiaxial-warp knitting process
To process the newly profiled reinforcement yarns into a grid-like reinforcement structure, a biaxial warp knitting machine Malimo 14022 at the ITM and the corresponding sub-processes (yarn feeding, weft yarn insertion, knitting process, impregnation and winding) were adapted and further developed so that on the one hand the pre-stabilized braiding yarns and the consolidated tetrahedral-shaped profiled rovings can be processed further. For this purpose, the weft thread laying process in particular was modified by developing a new type of weft thread guide for the laying of the pre-stabilized braiding yarns. Since the rigid profiled rovings could not be processed with the conventional weft laying process, a new type stick placement system consisting of a stick magazine and a shaft with profile rollers was developed (see Figure 2). The pre-cut sticks were individually inserted via the stick placement system into a transport chain modified with new fixing elements.

In order to guarantee textile processing, the pre-stabilized braiding yarns were impregnated and consolidated after the warp knitting process, contrary to the rigid profiled rovings, which do not require any further impregnation.. On the basis of extensive production tests, a new type of impregnation system was developed based on the kiss coater process with an additional coating roller for applying an impregnation agent to both sides of the pre-stabilized braiding yarns. Various reinforcement structures were manufactured and characterized with the implemented system technology. Figure 3 shows a new type of profiled textile reinforcement consisting of prefabricated profiled rovings with tetrahedral shape.

Acknowledgments
The IGF research project 21375 BR of the Forschungsvereinigung Forschungskuratorium Textil e. V. is funded through the AiF within the program for supporting the „Industriellen Gemeinschaftsforschung (IGF)“ from funds of the Federal Ministry for Economic Affairs and Climate Action on the basis of a decision by the German Bundestag.

The complete publication is available as download.

AutorInnen: Penzel, Paul; Hahn, Lars; Abdkader, Anwar; Cherif, Chokri

Technische Universität Dresden
Fakultät Maschinenwesen
Institut für Textilmaschinen und Textile Hochleistungswerkstofftechnik (ITM)
01062 Dresden

https://tu-dresden.de/mw/itm

More entries from TU Dresden, Institut für Textilmaschinen und Textile Hochleistungswerkstofftechnik ITM