Rheological Characterisation and Processability Window of Denim-Derived Cellulose Solutions in NMMO for Fibre...

Area of Science:

• Materials Science
• Polymer Chemistry
• Sustainable Textiles

Background:

• Cellulose fibre production commonly uses N-methylmorpholine N-oxide (NMMO).
• Spinning fibres from denim waste is challenging due to high viscosity, indigo dye, and NMMO's temperature sensitivity.
• These factors complicate denim dissolution and fibre regeneration for textile recycling.

Purpose of the Study:

• To comprehensively characterize the rheological and structural properties of regenerated cellulose fibres from waste denim dissolved in NMMO.
• To determine optimal spinning conditions for denim-derived cellulose fibres.
• To establish a rheological framework for sustainable textile recycling.

Main Methods:

• Oscillatory and steady-state rheological tests were performed on denim/NMMO solutions (4-8 wt%) at varying temperatures (60-90 °C).
• Steady shear tests evaluated shear-thinning behavior and mechanical predictability.
• Thermal ramp experiments assessed temperature limits for processability and structural integrity.

Main Results:

• A 6% denim/NMMO solution at 80 °C showed optimal rheological balance, moderate viscosity, and viscoelastic transitions suitable for air-gap spinning.
• Shear-thinning behavior and mechanical predictability were confirmed for spinneret extrusion.
• 80 °C was identified as the safe upper temperature limit, balancing processability and structural integrity.

Conclusions:

• The identified rheological parameters are consistent with spinnable cellulose dopes for air-gap spinning.
• This research provides a foundation for controlled fibre spinning and process scale-up in sustainable textile recycling.
• The study establishes a robust rheological framework for denim-derived cellulose in NMMO.