From Lab to Industry: Advanced Recycling of Elastane and Polyurethane
Less than 1% of clothing materials are recycled into new garments (closed-loop recycling), around 12% are downcycled into lower-value products (open-loop recycling), and approximately 73% end up in landfills or incinerators. [1] [2]
Finding suitable and innovative recycling processes for textile waste is therefore a priority, especially for fibre-to-fibre systems. However, only a few fibre-to-fibre recycling technologies currently are efficient, and most are highly sensitive to contamination, limiting their application to mono-material waste streams. SOLSTICE is working on developing more of these technologies.
SOLSTICE’s work on elastane
One of the major factors complicating recycling is elastane (EL), a fibre containing at least 85 wt.% of a segmented polyurethane, widely used in woven fabrics (2–10 wt%) and present at even higher levels in medical textiles (up to 50 wt%). In most fabrics, elastane forms the hidden core of core-spun yarns, wrapped by polyester, polyamide, or cotton to provide stretch, comfort, and enhanced appearance. This structure restricts mechanical separation of fibres and therefore hinders the recyclability not only of elastane itself but also of the main textile components it is blended with. Developing processes capable of selectively separating elastane from blended fabrics would thus make a significant share of today’s textiles suitable for recycling. [3] [4] [5] [6]
Building on previous studies, SOLSTICE partner Next Technology Tecnotessile (NTT) has validated a thermo-chemical pre-treatment process that can selectively separate elastane fibres from synthetic bi-component fabrics such as PES/EL and PA/EL, containing 5–20 wt.% EL. With this method, the polyester (PES) or polyamide (PA) fibres are cleaned from elastane, which is recovered after a filtration step from the solvent dispersion. This separation makes it easier to recycle the main textile components, i.e. PES and PA, which can then be used to produce non-woven panels for thermal and acoustic insulation applications or turned into recycled yarns according to a textile-to-textile approach.
At the same time, the SOLSTICE project is also exploring new options for recycling the recovered elastane. In particular, the partner DENGE is developing EL-based coating formulations for textile applications, while the partner Spin-PET is testing elastane as a toughening agent in polymeric blends through reactive extrusion compounding.
As part of the SOLSTICE project, Spin-PET is also investigating an upcycling approach that directly reuses bi-component textiles without prior fibre separation. Using its patented compaction method, the fibrous material (i.e., PET/EL and PA/EL) is densified and employed as toughening agent in polymeric blends through a reactive extrusion process. The resulting compounds are characterized according to different test methods, and they are suitable for applications such as injection moulding and 3D printing.
SOLSTICE’s work on polyurethane
A similar challenge exists with polyurethane (PU) coatings which are common in textiles due to the fact that they make fabrics durable and high performing, but they are very hard to recycle. Their chemical complexity, especially the additives, dyes, and other tightly bonded components, makes both mechanical and conventional chemical recycling difficult. As a result, PU-coated textiles often end up as waste with no practical way to recover them, showing the need for new recycling solutions like those studied in SOLSTICE. Addressing this issue is important for improving material circularity and reducing environmental impact. Developing suitable chemical recycling methods could allow the recovery of valuable components and reduce the use of virgin polymers.
Complementing the work on EL-containing textiles, SOLSTICE also addresses the recycling challenges of polyurethane coatings. Leitat Technological Center works on this matter, focusing on defining and optimising the full set of chemical recycling parameters for polyurethane-coated textiles, covering separation steps, depolymerisation conditions, repolymerisation routes, and validation of the recovered materials. To develop robust and reliable processes, experiments are first carried out with pre-consumer waste. This approach lays the groundwork for applying the methodology to post-consumer streams and, eventually, for scaling up the process.
How do these processes work?
SOLSTICE’s work on elastane
Figure 1: Pre-consumer PES/EL and PA/EL fabrics treated in NTT’s pilot plant.
The SOLSTICE project aims to keep common textile blends out of landfills and incinerators by improving their recyclability. Elastane is a major obstacle to fibre-to-fibre recycling, as even small amounts can hinder commond recycling processes. By dissolving and removing EL from bi-component blends, SOLSTICE enables the recovery of the main fibres, such as PES and PA.
Tests carried out in SOLSTICE show that the solvent-based method can separate almost all EL from bi-component PES/EL and PA/EL fabrics. The recovered PES and PA have already been reused to produce non-woven panels and recycled pellets to produce new yarns. The separated elastane is being tested in new applications as well: DENGE is developing EL-based textile coatings, while Spin-PET is using EL as a toughening agent in polymeric blends through reactive extrusion. These solutions support circularity and reduce the need for virgin materials.
SOLSTICE is also exploring an upcycling route that reuses bi-component textiles without separating their fibres. Using project partner Spin-PET’s patented densification method, the materials are compacted and co-extruded with r-PET or r-PA to create blends suitable for injection moulding and 3D printing. Their properties will be compared with virgin and benchmark materials.
Figure 2: Pre-consumer PA/EL fabric, before (left) and after (right) the elastane removal treatment.
NTT’s technology uses a closed-loop solvent system that selectively separate elastane from bi-component PES/EL and PA/EL textiles. The approach has been successfully tested on pre-consumer textiles and it will be replicated for post-consumer textile waste. As an example, Figure 2 shows a pre-consumer PA/EL fabric before and after the process: a clear increase in the transparency and in the lightness of the fabric was observed, due to the removal of the elastomeric fibres.
Figure 3: Chemical recycling methodology of pre-consumer textile waste
SOLSTICE’s work on polyurethane
In parallel, SOLSTICE also addresses the recycling of PU-coated textiles. Leitat Technological Center builds on its previous projects involving the depolymerisation of flexible and rigid PU foams via glycolysis, where recovered oligomers and polyols were successfully reused to produce new polymers. This experience provides a solid starting point for exploring similar approaches for PU coatings.
Glycolysis is a well-established method for depolymerising PU foams, but it has not been applied to PU coatings in the textile sector. The main challenge is the complexity of coated textile products, which include additives and dyes that influence depolymerisation and complicate purification. The goal within SOLSTICE is to demonstrate that glycolysis can be used to recover monomers and oligomers from polyester-based PU coatings and to test whether these recovered materials can be reused in new applications. This would contribute to establishing a circular use cycle for PU-coated textiles.
The approach uses glycolysis to break down PU coatings into monomers and oligomers. These recovered fractions are intended for reuse by CROMOGENIA in new textile-related polymers or adhesives for different applications and by INDRESMAT for foam applications in the building sector.
The Current State of Textile Recycling
While mechanical recycling is preferred when possible because it is cheaper, simpler, and has a lower environmental impact, it only works with homogeneous textiles and handles about 21% of collected waste. Blends such as PET/EL, PA/EL, or PU-coated textiles are difficult to recycle mechanically, as they reduce fibre quality and often prevent fibre-to-fibre recycling, leading to downcycling, incineration, or landfilling. Elastane is a major barrier because even small amounts block the recovery of PES and PA. Fibre-to-fibre recycling preserves fibre quality, reduces reliance on virgin materials, and keeps textiles in circulation, but it requires new approaches for challenging materials.
In SOLSTICE, an innovative closed-loop solvent process will be optimized to selectively separates EL from bi-component textiles (i.e., PES/EL and PA/EL), producing two recyclable outputs: EL and purified PES or PA textiles. The recovered PES or PA can be reused in the textile sector, while EL is explored as component for textile coating formulations and as a toughening agent in polymeric blends.
The upcycling approach by reactive extrusion proposed within the SOLSTICE project could be consider an advantageous strategy for the textile sector. In fact, the direct reuse of bi-component textiles eliminates the need for prior grinding of voluminous textile materials, thereby avoiding issues related to the low bulk density of ground materials and facilitating a simple, cost-effective, and versatile integration into conventional extrusion processes.
Finally, PU-coated textiles are addressed through the first adaptation of a well-established glycolysis process, previously used for PU foams. This process breaks down the coatings into reusable oligomers and monomers, which are then reused for the obtention of new polymers for several applications into textile sector or adhesives via CROMOGENIA or into building-sector foams via INDRESMAT, creating new circular pathways.
Together, these complementary approaches, targeted EL separation, upcycling bi-component textiles, and chemical recycling of PU-coated materials, form a comprehensive strategy within SOLSTICE to overcome some of the most critical barriers to textile-to-textile recycling.
Conclusions and next steps
The results achieved in the work of the SOLSTICE partners demonstrate innovative advances that provide concrete benefits across the textile value chain. Optimising process parameters for the closed-cycle solvent system in NTT’s pilot plant, using pre- and post-consumer bi-component textiles, will improve efficiency, product quality, and sustainability by maximising yield, reducing waste and energy use, and ensuring consistent, scalable outcomes.
Scaling up Spin-PET patented densification method for textiles, prior to their processing by reactive extrusion process, could enable the efficient recovery of mixed fabrics and their conversion into high-value materials. Through process optimisation, this approach can be integrated into existing production lines, reducing costs and environmental impact while supporting circular manufacturing. Within SOLSTICE, Spin-PET will produce around ten kilos of toughened polymeric blends, demonstrating the potential of direct textile reuse for applications such as injection moulding and 3D printing.
DENGE will evaluate the application of EL-based formulations at larger scales to produce coated technical textiles, addressing the growing need for more sustainable coatings made from recycled materials. These solutions reduce reliance on virgin resources, support circularity, and maintain high fabric performance.
In parallel, the depolymerisation process for PU coatings has been optimised at laboratory scale. The next step, with support from CROMOGENIA, is to scale the process under industrial conditions and apply it to post-consumer PU-coated textiles. These heterogeneous and contaminated materials present additional challenges in filtration, separation, and purification, requiring further optimisation to ensure consistent output quality. This work will be carried out in close collaboration with CROMOGENIA and INDRESMAT to ensure that the recovered materials meet the technical requirements for their intended applications.
