Coming Full Circle: Innovating towards Sustainable Man-Made Cellulosic Fibres
Why closing the loop in MMCF production remains a challenge
As introduced, the current fashion system is operating in a linear manner of extracting virgin resources and disposing of clothing once it has reached its perceived end-of-life, generating a huge amount of waste. Textile-to-textile recycling holds significant potential to close the loop in MMCF – alleviating the strain on virgin resources (problem 1) and reducing the amount of used textiles going to landfill / incineration (problem 2). Moreover, using cotton waste is more efficient than virgin wood from a yield perspective given the purity of cellulose in cotton. It only requires approximately 1 tonne of cotton waste to generate 1 tonne of cellulosic pulp, compared with 2.5 – 3 tonnes of wood required for the same 1 tonne output30.
Closing the loop in MMCF through textile-to-textile recycling can be done in two main ways – mechanical and chemical recycling. Mechanical recycling is a more established industry, with roots in the ‘downcycling’ industry – that is, producing materials used in insulation, industrial clothes or other lower-value uses. Mechanical recycling of textiles into new textiles is commonly done on high purity, long staple fibres such as wool and cashmere. The mechanical recycling process involves breaking down garments by chopping them into shredded fragments, pulling apart the fibres and then disentangling and aligning them using a carding process31.
Inherent to the mechanical recycling process is the shortening of the fibres, reducing their performance during the yarn and fabric production. This makes it challenging to achieve the desired versatility and quality of finished garments using mechanically recycled fibres. It can therefore be argued that mechanical recycling of cotton does not provide a ‘truly circular’ solution given the continued degradation of fibre lengths in each cycle32. To combat this, the recycled cotton fibres are often blended with virgin ones, improving the performance but worsening the environmental footprint of the final output.
Moreover, textile-to-textile mechanical recycling solutions require a high purity of feedstock. The low tolerance for contamination of other fibres is especially problematic given the high prevalence of blended fabrics entering the post-consumer waste stream – with research from the Netherlands estimating it to be around 40% of post-consumer textiles33. Finally, given mechanical recycling does not change the colour of the garments, they must be manually sorted into groups of colours, increasing labour costs to the process. Given all of the above, it could be said that textile-to-textile mechanical recycling has greater applicability to the post-industrial (rather than post-consumer) textile waste stream – whereby there is greater assurance of homogeneity of feedstock in terms of purity and colour.
On the other hand, chemical recycling of textile waste provides an encouraging alternative as it is able to overcome some of mechanical recycling’s shortcomings. From a process perspective, chemical recycling breaks down the fibres into their chemical building blocks, then rebuilds them into new fibres of indistinguishable, or even superior quality34.
Emerging chemical recycling technologies are also able to address blended-fibre garments. For example, polyester and cotton possess very different solubility characteristics, allowing for chemical recycling to separate and extract both fibres in a polycotton blend35. Specifically to cotton, which accounts for almost a quarter of the global fibre market, the process generally involves dissolving the cotton cellulose in a solvent and then wet spinning new fibres from the resulting pulp, in a similar way to the conventional viscose process and other man-made cellulosic fibres36.
Whilst the technology holds great potential to close the loop on much of the textile waste, it still has a few crucial barriers to scale. First, aside from a few examples, investors have not demonstrated great appetite in the space, with the investments being perceived as too risky given the high capex costs and the long timeframe to commercialisation. Moreover, the perceived risk of the technology is compounded by the lack of formalised brand engagement with innovators – on the whole there seldom exists offtake agreements and other co-development contracts. Without the demand for the offtake signalled, it is challenging to attract financiers into the space.
Finally, given the lack of capital invested in the emerging industry, it has proven extremely challenging for innovators to reach cost-parity with the virgin alternative, whilst the output remains relatively small scale37. The relationship between the stakeholders can be characterised by the chicken and egg analogy – brands will not formally commit to offtake until it is cost competitive with virgin fibre; however, investors will not finance the innovation to commercialisation without the lack of demand signalled from the brands – leaving innovators in a difficult position.