| Author: | Hu, Lingquan |
| Title: | A circular economy approach - post-consumer textile waste recycling for 3D printing flexible textiles |
| Advisors: | Jiang, Shouxiang Kinor (SFT) |
| Degree: | Ph.D. |
| Year: | 2024 |
| Subject: | Textile waste Textile fabrics Three-dimensional printing Hong Kong Polytechnic University -- Dissertations |
| Department: | School of Fashion and Textiles |
| Pages: | xxii, 170 pages : color illustrations |
| Language: | English |
| Abstract: | Three-dimensional (3D) printing filament has recently been producing by using recycled materials from 3D printing waste and other sources. With the developments of material recycling processes, a new source referred to as post-consumer textile waste (PCTW) can be used to produce filaments for 3D printing textiles. However, several challenges impede thermoplastic recycling from PCTW for 3D printing. The flowability of the polyester recycled from PCTW is too high to be extruded into 3D-printable filaments, which must be adjusted by additives. The mechanical method is rarely investigated for recycling thermoplastic polyurethane (TPU) films into 3D-printable filaments. Moreover, the development of 3D-printable filaments is restricted by limited applications, which should be expanded to encourage polyester textile and TPU film recycling. To address these challenges, this thesis investigates the material properties of polyester and TPU recycled from polyester textiles and TPU films. It also discusses the potential applications of polyester and recycled TPU (rTPU) filaments for 3D printing textiles. In this study, the clean textiles were hot-pressed into a paper-thin plastic board. After air-cooling, the plastic board was ground with ADR 4468 into powders. The extruder mixed, melted, and shaped the powder into 3D printing filaments. The polyester filaments were printed into specimens for further tests to improve the mechanical properties of materials and then printed into textiles with different structures to enhance flexibility. TPU film recycling is accomplished by breaking the film into plastic fragments, which are then extruded into filaments. After 3D printing, the specimens were tested to improve the mechanical properties of materials, and the textiles with distinct structures were tested to enhance flexibility. The polyester mixed with 1.0 wt% of ADR4468 (rPET/ADR4468-1.0 wt%) exhibited the highest tensile and compressive strengths. The optimal content of ADR4468 improved the processability of filament extrusion and 3D printing, enhancing the mechanical properties of 3D-printed materials. The rTPU showed high chemical and thermal stability, and high elasticity. The tensile properties and processability of 3D printing products were further improved using the rTPU filaments dried at 25°C and 25% relative humidity for 48 h. The flexibilities of rPET/ADR4468 textiles were improved by low infill density and intersection angle. The anisotropy of flexibility was observed in low-intersection-angle textiles, significantly improving the flexibility in the weft direction. The improved flexibility of the rTPU textiles was achieved with low infill density, a rotation angle of 45°, and fewer layers improved flexibility. This study discusses the potential approach to recycling polyester textiles and TPU films into filaments for 3D printing textiles. The method is expected to enhance the value of the polyester textiles and TPU films recycled from PCTW. It would stimulate the recycling industry to identify the thermoplastics and sort them for further recycling. Due to the stimulation, thermoplastic PCTW storage would decrease rapidly via mechanical recycling instead of chemical degenerating and landfilling. Thus, the approach would provide sustainable filaments, expand the applications, increase the recycling rate of polyester textiles and TPU films from PCTW and reduce the environmental loading for the disposal. |
| Rights: | All rights reserved |
| Access: | open access |
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