New quality fibres from synthetic fibre waste

Some call it "molecular recycling", others "chemical recycling". In fact, it is a family of various technologies that promise to obtain fibres with virgin-like technical performances, starting from polyester and polyamide waste and polyolefins such as polypropylene and polyethylene, all materials today mostly of fossil origin.

 

These fibres account for over 2/3 of the materials used, considering both fashion and technical textiles. Improving the possibilities for their reuse could, therefore, significantly contribute to reducing GHG emissions and the volume of wasted resources. These recycling technologies also offer an additional bonus. They allow the separation of different materials during the regeneration of fibres of mixed fabrics and yarns. An example is polycotton fabrics. Recycling polycotton fabric scraps yields PET (Polyester) on one side and cotton – not spinnable but ready for cellulose - extraction on the other.

 

It is an innovation of no minor importance. If we consider, for example, polyester, up to now, the recycling of fibres used in textiles has been limited to downcycling as a thermo-binder material in nonwoven processes for insulation and padding. All the recycled polyester that is now frequently found in garments comes, for reasons of performance of the recycled fibres, from the thermomechanical recycling of PET bottles.

 

However, it is also a controversial issue. This family of technologies requires large quantities of energy, thermal or electrical, for the chemical reactions to occur that regenerate the fibres by breaking and then recreating the polymer chains that make up the fibres, a condition dictated by the laws of thermodynamics and, therefore cannot be avoided. Furthermore, some of the variants of these technologies require an extensive use of chemical solvents, which then become waste.

 

Therefore, it is necessary to carefully evaluate and measure the positive and negative impacts from an environmental perspective. The conditions for the desirability of the application of these technologies can be summarized in a few points.

 

The first condition concerns energy use, not necessarily the quantity of energy, but the type of energy used. A technology that predominantly uses electricity can be powered by renewable sources, such as solar, wind, etc., while technologies that predominantly use thermal energy use gas.

 

The second condition is the preference for technologies with low use of solvents.

 

The third condition concerns the existence of a supply chain for the collection of textile scraps and waste of synthetic or mixed fibres. Without an effective and efficient collection system, achieving the required feedstock volumes, their stability and compliance with the specifications required for recycling processes is difficult.

 

Last but not least is the economic and financial dimension. These technologies require high investments, between €100 and €200 million, for plants capable of processing approximately 50 thousand tonnes of waste annually. The investment is, therefore, substantial and cannot be separated from adequate profitability. To date, to be profitable, these technologies generally involve very high sales prices for regenerated fibres.