Case Studies


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.”


FET will provide two extrusion lines in separate phases in 2020-21:

1. Monofilament line, including water baths, drawing frames, ovens, dimension sensor, monofilament winders and dedicated control panel.

2. Multifilament line, including the extruder set-up and the multifilament drawing and winding frame with control panel.

The new extruders and spinning machines will furthermore enable Senbis to manufacture bicomponent yarns. “The typical requirements of yarns are good mechanical and thermal properties and e.g. chemical stability. This may be reached by utilizing multiple polymers and additives. This can be accomplished by compounding them, but also by combining the output of multiple extruders. For example, it will be possible to create a filament or fibre whose mantle consists of a different material than its core.”

Another area of potential is the development of filaments and powders for 3D printing. “Our spinoff Innofil3D was acquired by BASF and is flourishing. We aim to continue to facilitate this growth by providing support from our R&D facilities. Our cluster of companies and institutions together have a very strong proposition in additive manufacturing”.

This investment confirms Senbis’s commitment to sustainability despite the uncertainty generated by the Covid-19 pandemic “We are convinced that the sustainability trend, which only just started in the plastics sector, will only grow stronger in the coming years.”