A Method for Mitigating Degradation Effects on Polyamide Textile Yarn During Mechanical Recycling.

Area of Science:

• Materials Science
• Polymer Chemistry
• Sustainable Engineering

Background:

• Fast fashion generates significant textile waste, necessitating sustainable end-of-life solutions.
• Environmental regulations and landfill restrictions drive the need for effective textile recycling methods.
• Polyamide 6.6 (PA66) is a widely used textile material facing recycling challenges.

Purpose of the Study:

• To investigate the mechanical recycling of PA66 yarn.
• To evaluate the effectiveness of a chain extender (Joncryl) and antioxidant (Irganox) in improving recycled PA66 properties.
• To confirm the suitability of these additives for creating recyclable textile-grade PA66.

Main Methods:

• Mechanical recycling of PA66 yarn with Joncryl and Irganox.
• Thermogravimetric analysis (TGA) for thermal stability assessment.
• Differential scanning calorimetry (DSC) to measure oxidative-onset temperature (OOT).
• Gas chromatography-mass spectrometry (GC/MS) for degradation product identification.
• Mechanical testing (Young's modulus) and viscosity measurements.

Main Results:

• Recycled PA66 maintained thermal stability, with Joncryl further enhancing it.
• DSC confirmed improved oxidative stability with additive use.
• GC/MS identified degradation products linked to polymer matrix changes.
• Young's modulus initially decreased but recovered with further processing, indicating chain modification.
• Viscosity and limiting viscosity number increased up to 50% with additive concentrations.

Conclusions:

• Joncryl and Irganox significantly enhance the viscosity, mechanical strength, and thermal stability of recycled PA66 yarn.
• The additives facilitate the formation of new linkages and modified polymer chains.
• The study confirms the suitability of Joncryl and Irganox for producing recyclable textile-grade PA66, promoting a circular economy in textiles.