In the Spinning Tower of ITA

As part of the ITA Group, the ?Technical Fibres? department is a leading research, education and qualification provider for fibre-based high-performance materials, textile semi-finished products and their manufacturing processes.

TThe ?Technical Fibres? department of the Institut für Textiltechnik of RWTH Aachen University (ITA) is a global leader in industry-oriented research in melt spinning. The department sees itself as the world?s first point of contact for innovative fibres with a focus on recycling, process optimisation, material development and functionalisation.

As part of the ITA Group, the ?Technical Fibres? department is a leading research, education and qualification provider for fibre-based high-performance materials, textile semi-finished products and their manufacturing processes. The research covers the entire textile value chain, starting with natural and synthetic raw materials, through yarns and their further processing to textile surfaces and composite materials, to textile semi-finished products and finished products. The long-standing cooperation with industry, in particular small and medium-sized enterprises, ranges from joint research projects for the development of innovative processes and products to technical and strategic consulting in complex problems concerning man-made fibre technology, textile processes and digitisation.

With a renowned team of young experts, we offer industry-oriented research in melt spinning in the excellent research environment of RWTH Aachen University and ITA. We put our worldwide pioneering role to the test on a daily basis through many years of industrial cooperation with numerous companies in many branches of industry. Every finding from basic research is important to us. The goal, however, is always to integrate this knowledge into an industrial process or product sooner or later.

– Robert Brüll, Head of ?Technical Fibres? Department

For more than 50 years, a team of 30 scientists, technicians and students has been researching polymer fibres and their production in the ?Technical Fibres? department with the aim of establishing them in a multitude of new applications. The core competencies of the department include the areas of material systems, process development, high-performance fibres and digitalisation (Figure 2). The focus here is on an integrated process consisting of industry-oriented research and industrial services.

Customers and partners along the entire textile process chain are advised and supported with state-of-the-art machinery. This process chain begins with the selection of materials and raw materials and ends with the final product for the given field of application. In our own spinning tower, melt spinning systems are available from laboratory to industrial scale (Figure 3). In addition to monofilament and multifilament plants for single and bicomponent fibres, these also include material preparation in the form of drying and compounding as well as plant technology for texturising. The range is rounded off by the institute?s own testing and polymer laboratories, which can determine the relevant material and fibre parameters in accordance with industrial standards.

A wide variety of material combinations characterise the process chain in the ?Technical Fibres? department. All common man-made fibre materials are processed. These include, among many others, PP, PE, (r) PA, (r) PET, PEI and PEEK. Biopolymers such as PLA, PHB and PBAT are also processed into fibres.

Together with its extensive network of partners, ITA is able to map almost all common fibre-processing steps in the textile process chain (Figure 4). These include coating, texturing, drawing and twisting. The processes for further processing the fibres into various textile structures such as woven and knitted fabrics, braids (round and 3D), nonwovens and preforms are similarly broad.

The wide range of textile production processes at the ITA guarantees that not only new types of fibres and fibre-based materials are produced in research projects, but that these can also be further processed into textile semi-finished products and finished components. The wide range of textile production processes at the institute results in countless design possibilities and a huge range of applications, from light-emitting textiles to fire-resistant clothing, from medical implants to textile concrete and from sportswear to car interior textiles.

The infrastructure for upstream, intermediate and downstream analysis has a broad base in the ?Technical Fibres? department and at ITA. Optical measurement methods for fibre orientation and 3D deformation as well as laser Doppler anemometry (LDA), particle image velocimetry (PIV) and high-speed and thermographic cameras are offered at ITA. All standards for fibre, yarn and fabric testing are avail-able in our own air-conditioned textile testing laboratory. This includes automated single fibre testing, tensile-pressure bending tests up to 10 t with a temperature chamber and video extensometer as well as microscopy analysis (digital light microscopy, SEM, Micro-CT, TEM). In addition, a polymer laboratory provides various measuring methods such as DSC-TGA, DMA, FT-IR, gas pycnometer, rheometry and Karl Fischer titration.

With six core research areas recycling, filled fibres, shaped fibres, amorphous fibres, digitisation and texturing & analytics (Figure 5), ?Technical Fibres? has built up a position offering great potential for the future.

The linking of melt spinning with the methodology of Design for Recycling is being investigated in the division of ?Technical Fibres? as part of a research project funded by the BMBF. A soluble sewing thread made of polyester is being developed for the separation of mixed textile waste. The basis for the separation of the composites is a novel microcapsule system, which is incorporated into the sewing thread in the melt spinning process. The polar capsules are only activated by targeted microwave irradiation at the recycler, i.e. at the end of their life cycle, and cause the destruction of the composite.

In the field of particle-modified fibres, innovative fibres such as inductively heatable fibres for cancer treatment, carbon-additive, electrically conductive fibres with good washability or agricultural textiles with pest-effective modification are being researched. In addition to these, component developments are also being promoted. These simplify or improve the processability of particle-modified melts into fibres independently of the particle system. New filter systems for processing several melt streams with high particle contents have recently been developed to extend the operating times of the filter.

Research on shaped fibres includes both process and product-side projects. On the process side, the shape formation in the extrusion process is investigated in order to generate a higher correspondence between the filament geometry and the capillary geometry. On the product side, research is being carried out in particular on the development of new fibre cross-section geometries for the targeted functionalisation of textiles. For this purpose, profiled multifilaments made of flame-retardant polyester are currently being developed for use in acoustics (household and home textiles, transportation). A partially automated and geometry-independent form factor determination method was developed for quantitative control of the quality of the fibre cross-sections.

In the field of amorphous fibres, polymer optical fibres (POF) and their applications are investigated. In recent years, a cost-saving continuous manufacturing process for POF with gradient index has been developed. Currently, research is being carried out on a textile touchpad based on POF and on the optimisation of side light activation for lighting applications.

Digitisation has found its way into the spinning tower at the ITA, too. An extraction of all data from the melt spinning process is currently being implemented. Industry 4.0 approaches for online quality monitoring, predictive maintenance and product traceability are being investigated.

A new, modular test bench is currently being set up to map the false twist texturing process. In a current research project, a novel twist unit is being tested to increase the process speed for processing spun-dyed yarn by up to 40 per cent.

The ?Technical Fibres? department is currently conducting research in two Industry Research Groups (IRG). These are consortia of companies that carry out practical and industrially oriented research together with the ITA. Technological as well as economic and strategic questions on relevant topics in textile technology are addressed.

The members of the IRG determine a research topic which is researched exclusively by the ITA for the consortium members.

The IRG ?Meltspinning? deals thematically with the modelling of the melt spinning process. The over-riding goal is to enable a conclusion of desired yarn properties from process parameters. The relation-ship between material properties in the process, resulting yarn properties and process parameters is systematically analysed and converted into a model. In the second IRG ?Polymer Recycling?, the recyclability of textiles and the processing of recycled materials will be analysed and extended. The vision of the consortium is that 100 per cent of all textile waste can be recycled and processed into high-quality textile end products.

In addition to research activities, there is of course also teaching at a university institute. However, the range of courses is not limited to students of RWTH Aachen University. The ITA Academy offers seminars and training courses tailored to industrial partners for companies wishing to establish new products or processes in their own operations or for employees wishing to refresh lost knowledge. The ?Technical Fibres? department is looking forward to developing future innovations together with you.

ABOUT THE AUTHOR:

The article is authored by Jan Kallweit, M. S.c; Jeanette Ortega, M. S.c; Dr. Robert Brüll, M. Sc.; and Univ.-Prof. Prof. h.c. (MGU) Dr.-Ing. Dipl.-Wirt. Ing. Thomas Gries