Master's thesis on recycling fabric blends containing elastomers awarded at Ecomondo

On November 6, the "Textile District" area of the Ecomondo trade show in Rimini, hosted the award ceremony for the "Innovation, Recycling, and Reuse in Textiles" competition, recognizing the best theses and final projects from ITSs (Higher Technical Institutes). The award, promoted by Federcanapa and Chimica Verde Bionet, was supported by Centrocot, Confindustria Moda, Linificio e Canapificio Nazionale, SAFE, CNA Federmoda, GEA, GreenThesis, and GreenEvo.

 

One of the winning projects proposed an engineering solution to the widespread problem of elastomers in fabrics -- a factor that, as highlighted in a previous article, significantly reduces the efficiency of mechanical and thermomechanical recycling processes, often making the recovery of textile fibers practically impossible.

 

The author of the Master's Thesis "Sustainable reuse of textile fibers: separation and purification of elastomers from waste fabrics" is Marco Frigola, who graduated from the Master's Degree Course in Chemical Engineering at the Department of Civil and Industrial Engineering, School of Engineering, University of Pisa. The thesis supervisors are Prof. Cristiano Nicolella and Dr. Mariangela Guastaferro.

 

Thesis results 

The award-winning thesis presents an innovative method for treating fabric blends aimed at removing elastane, purifying the remaining fibers — usually cotton or polyester — and returning them to the recycling chain.

 

The thesis highlights three main areas of interest. The first, already mentioned, is the need to find a solution for removing elastomers from fabric blends, which make up a significant portion of textile waste. The second is the search for a low-impact process that allows solvent recovery in a closed cycle. The third is the potential re-use of the recovered elastane.

 

The main results of the thesis are summarized below:

• Identification of the most efficient selective elastomer solvent: Through a comparative analysis of literature data and the application of theoretical models based on Hansen Solubility Parameters, several solvents were selected and tested. Among these, dimethyl sulfoxide (DMSO) showed the greatest dissolving power against elastane.
• Experimental verification of dissolution: Tests confirmed the ability of DMSO to selectively dissolve elastane while preserving cotton. The experiment also demonstrated that DMSO is not suitable for separating elastomer from protein fibers such as wool, which is completely dissolved by the solvent. The treatment requires about one hour of contact time at temperatures between 120 and 140 °C.
• Characterization of the recovered material: The extracted elastane retains the same thermal properties as the original material, as shown by thermogravimetric (TGA) and calorimetric (DSC) analyses. This result confirms the possibility of reusing the recovered polymer without performance loss. The thesis illustrates a potential application of the recovered elastane as a filler and toughening agent for brittle polymers such as bioplastics from renewable resources, including PLA (polylactic acid).
• Design of an industrial plant: Finally, the thesis describes and defines the characteristics and dimensions of an industrial facility for the separation, recovery, and reuse of both elastane and the solvents employed.