Browsing by Subject "Mechanical Recycling"

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    Textile Mechanical Recycling: Design, Improvement, and Analysis of a Carding Wire Drum System
    (2023-12) Teixeira Franca Alves, Paulo Henrique
    Textile manufacturing is responsible for significant environmental impacts such as 35% of primary microplastics production, 20% of global clean water pollution, and 10% of global greenhouse gas emissions. The growing problem of textile waste, further fueled by fast fashion and overconsumption, is set to grow with the rising global population. In 2018, 17 million tons of textile waste was generated in the US of which only 15% was recycled. Furthermore, only 1% of recycling policy research focuses on textile waste, demonstrating the great need for new studies and technologies to mitigate this problem. Additionally, present textile recycling technologies produce downcycled fibers, have high costs, or lack scalability for industrial production volumes. Despite the existence of various shredding machines for recycling textiles, the parameters that can influence this process have not been broadly investigated, decelerating the development of machines that could make fiber-to-fiber recycling a possibility. This study investigates the principles behind carded (toothed) drum textile shredding, to optimize the shredding process to obtain reusable fiber while decreasing the generation of fabric pieces and dust. The mechanics involved in subjecting fabrics to tensile and shear forces in a carding wire drum-operated system were investigated to understand better how the textile material behaves during the shredding process. By focusing on the interaction between the feeding and shredding drums and characterizing the failure mechanics of the drum-textile and tooth-yarn interactions, it was proposed that reducing tooth size and increasing the relative speed between drums will enhance the shear failure ratio, increasing the output of fibers and yarns. Because most existing textile recycling technologies are expensive, yield low-quality outputs, or lack scalability for industrial use, there is an urgent need for adaptable and sustainable textile recycling system designs that account for the dynamic nature of the textile and fashion industry. To ensure sustainability, these designs must be flexible enough to adapt to technological advancements, user needs, societal changes, and environmental conditions. To make this possible, flexible and sustainable principles were evaluated and overlapping principles were combined while missing principles were added, creating the design for sustainability and flexibility method (DfSFlex). The Fiber Shredder, a textile mechanical recycling machine, was developed with a focus on flexibility and sustainability and was evaluated based on how well it addressed the DfSFlex principles. The design and assembly processes of this machine were detailed to illustrate the decision-making involved in developing the technology. Later, a performance evaluation of the Fiber Shredder was performed and indicated that increased speed and processing time led to a higher generation of desired outputs (fibers and yarns) reflecting the principles of Design for Separation and Facilitate Resource Recovery in both design and processing. Furthermore, tests involving different materials and fabric structures demonstrated that material type, fabric thickness, and structure significantly influenced the output of recycled fibers. The Fiber Shredder outperformed an industrial shredding machine by producing outputs with fewer undesirable fabric pieces, more desirable fibers and yarns, and lower process losses. However, while effective for laboratory research purposes, the Fiber Shredder has limited capacity and requires automation and scaling up to meet industrial demands. Nonetheless, the development of this technology utilizing sustainable and flexible design principles shows promise in mechanical fiber-to-fiber recycling, contributing to the repurposing of textiles and reducing the amount of textile waste ending up in landfills.