Case Studies – Sustainability


An increasing proportion of FET orders specify a requirement for sustainable polymer source, recyclability and other elements of sustainability. Many customers require full confidentiality, which we respect so are not able to share as many case study stories as we would like. However, we are in the process of compiling a variety of interesting case studies and hope to add to these shortly.


Recycled PET + Breakdown Additive (DT975)

FET has extensive knowledge in designing equipment and developing processes for manufacturing polyester yarns, as well as expertise in using challenging materials like recyclates and additives. The R&D team worked closely with the customer to develop an experimental plan for the project, defining the material formulations to trial as well as the target properties for the end product. Working under a Non-Disclosure Agreement, the team performed extrusion and post-processing trials at the FET Process Development Lab pilot facility in Leeds.


The initial phase of work was to conduct a series of exploratory spinning trials, introducing the additive at various dosage levels and attempting to melt spin the formulations as multifilament yarns, as well as establishing baseline processing conditions and confirming manufacturing feasibility. Data gathered through the trial, showing what impact the inclusion of the additive had on manufacturing processing, output rates and product properties, was shared with the customer. The team was successful in producing a fibre product from a formulation of recycled polymer plus additive, which met the customer’s specifications.

The next phase was to produce batches of fibre using carefully controlled and monitored conditions. Multifilament yarns were spun, texturised and cut to produce staple fibre samples which were supplied to the customer, enabling them to progress the project to final application testing and end-of-life product analysis stage.



Senbis Polymer Innovations B.V. Netherlands

Senbis is a leading Dutch technological company, dividing its activities between R&D services and the production of sustainable polymeric products.

The company is investing 5.5 million euros over the next three years in a testing facility for the development of sustainable plastics at different scales ranging from laboratory to production. This will facilitate the acceleration and upscaling of future developments relating to sustainable plastics.

FET’s contribution to the project is to provide pilot extrusion lines with unique capabilities to produce technical yarns as well as textile fibres.

A Senbis spokesperson commented: “It is a welcome addition to our current facilities that focus on technical yarns. The new line now enables us to develop textile fibres from e.g. recycled polymers or biopolymers. Up until now, we were not able to answer questions in this field properly because we did not have the right equipment, even though we had all the relevant knowledge and analytical capabilities.”



Laboratory Spunbond system, University of Leeds

This FET spunbond system is now an integral part of the research facilities of the CCTMIH (Clothworkers’ Centre for Textile Materials Innovation for Healthcare), led by Prof. Stephen Russell based in the School of Design, University of Leeds, who commented “The new spunbond system is perfectly suited to our academic research work, and is already proving itself to be extremely versatile and intuitive to use”.

This spunbond system complements existing research lab facilities at the university, which covers all areas of fibre and fabric processing, physical testing and characterisation. It forms part of a wider investment in facilities to support fundamental, academic research on ‘future manufacturing’ for medical devices, where the focus is on studying small-scale processing of unconventional polymers and additive mixes to form spunbond fabrics with multifunctional properties.

Key to this research is developing the underlying process-structure-performance relationships, based on the measured data, to provide detailed understanding of how final fabric performance can be controlled during processing.

As a rule, many exciting materials developed in academic research struggle to progress beyond the bench, because of compatibility issues with key manufacturing processes such as spunbond. By leveraging mono, core-sheath and island-in-the-sea bicomponent technology, the Leeds University team is working with polymer and biomaterial research scientists, engineers and clinicians to explore the incorporation of unusual materials in spunbond fabrics, potentially widening applications.