A Critical Review of Advances in Mechanical Cotton Recycling for Sustainable Denim: Strategies to Overcome Fibre Quality Degradation, Dr Azzam Ahmed, Dr Ramadan Awed, Prof. Hasabo Ahmed

Dr Azzam Ahmed
Department of Textile Engineering, College of Engineering and Technology of Industries
Sudan University of Science and Technology
Khartoum
Sudan
ORCID: 0000-0001-9454-1921

Dr Ramadan Mohmmed Ahmed Awed
Department of Textile Engineering, College of Engineering and Technology of Industries
Sudan University of Science and Technology
Khartoum
Sudan
ORCID: 0000-0002-9319-2413

Professor Hasabo Abdelbagi Mohamed Ahmed
Department of Textile Engineering, College of Engineering and Technology of Industries
Sudan University of Science and Technology
Khartoum
Sudan
ORCID: 0000-0002-5095-8650

Purpose: This critical review examines the challenges of fibre quality degradation in mechanical cotton recycling for sustainable denim and highlights strategies to advance a circular textile industry.
Design/Methodology/Approach: A comprehensive review of recent literature and industrial trials was conducted, focusing on optimised blending, chemical innovations, and process improvements. The review integrates technical advancements with industry initiatives to present an holistic roadmap.
Findings: The main challenge is fibre quality loss (length and strength) during recycling. Solutions require optimising pre-processing, applying quality-driven blending (with virgin or recycled Polyethylene Terephthalate (rPET) fibres), and adopting short-fibre-tolerant yarn technologies such as core-spun, rotor, and air-jet spinning. These methods enable up to 75% recycled content without compromising yarn performance.
Originality/Value: This paper provides a timely overview of post-2023 developments, shifting the focus from downcycling to process- and design-based upcycling, offering a roadmap for circular denim production.
Implications: While limited to mechanical recycling, true circularity requires fibre-to-fibre pathways and advanced sorting. The review provides practical guidance for manufacturers to incorporate sustainability into mainstream denim Stock Keeping Units (SKUs), supporting sustainability goals and advancing the circular economy.
Keywords: Mechanical Cotton Recycling; Fibre Quality Degradation; Sustainable Denim; Textile Recycling Strategies; Circular Economy.