Recycling Textiles: From Post-Consumer Polyester Garments to Materials for Injection Molding
Abstract
:1. Introduction
- Material Sorting: It is essential to sort homogeneous materials (monomaterials). In fact, when PET is mixed with cotton or other synthetic polymers, polymer composites or blends are formed in reprocessing [16]. Due to the different chemical structures, the compatibility between the polymers is limited, resulting in poor mechanical properties [17]. In the past several reactive processing methodologies were developed by researchers to overcome this issue in PET blends recycling [18,19,20,21]. Nowadays, sorting techniques based on spectroscopy [22], like for instance near-infrared spectroscopy [23,24] coupled with artificial intelligence systems [25], can be applied on an industrial scale.
- Compounding: The material obtained must be compounded by extrusion with appropriate additives, depending on the final application. This step could allow the flakes to be transformed into pellets suitable for injection molding, compression molding, or additive manufacturing. However, the material thus obtained should show the desired rheological properties. Generally, PET undergoes chain scission during compounding operations, resulting in a material with very high fluidity, not suitable to be processed in manufacturing technologies where a significant melt strength is required.
2. Materials and Methods
2.1. Materials
2.2. Processing
2.3. Characterization
3. Results
4. Discussion
5. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Compound | PET Flakes (g) | Chain Extender (g) |
---|---|---|
DC | Dark Colored (200) | // |
DC-An | Dark Colored (200) | Nexamite® M021200 (6) |
DC-Ox | Dark Colored (200) | Nexamite® M992000 (6) |
DC-J | Dark Colored (200) | Joncryl 4468 (1) |
LC | Light Colored (200) | // |
LC-An | Light Colored (200) | Nexamite® M021200 (6) |
LC-Ox | Light Colored (200) | Nexamite® M992000 (6) |
LC-J | Light Colored (200) | Joncryl 4468 (1) |
Processing Steps for Polyester Garments | Procedures and Parameters | Final Items |
---|---|---|
Compaction | Heating at 150–310 °C and grinding [29] | Flakes |
Extrusion | Drying in a ventilated oven at 150 °C for 3 h; single-screw extrusion with rotor speed set to 50 rpm, and temperature profile: 250, 260, 260, and 250 °C | Granules (pellets) |
Injection molding | Drying in a ventilated oven at 150 °C for 3 h; setting 260 °C and piston speed 80 mm/s; mold at room temperature; specimens quenched by immersion in water at 0 °C. | Specimens |
Flakes Color | Picture | MVR (cm3/10 min) | MFR (g/10 min) |
---|---|---|---|
WHITE | 16.9 ± 2.0 | 14.6 ± 2.3 | |
YELLOW | 10.3 ± 1.8 | 8.8 ± 2.1 | |
RED | 22.4 ± 3.9 | 18.9 ± 4.6 | |
BLUE | 51.2 ± 6.0 | 41.7 ± 7.4 | |
BLACK-1 | 65.5 ± 4.7 | 55.1 ± 5.6 | |
BLACK-2 | 74.5 ± 5.8 | 70.5 ± 6.1 |
Compound | MVR (cm3/10 min) | MFR (g/10 min) |
---|---|---|
DC | 44.5 ± 2.5 | 47.5 ± 2.7 |
DC-An | 38.2 ± 6.1 | 44.7 ± 7.1 |
DC-Ox | 41.9 ± 3.7 | 46.5 ± 4.1 |
DC-J | 26.1 ± 2.6 | 29.4 ± 2.9 |
LC | 24.25 ± 0.7 | 27.7 ± 0.8 |
LC-An | 9.9 ± 1.7 | 11.6 ± 1.9 |
LC-Ox | 18.3 ± 2.7 | 21.0 ± 3.1 |
LC-J | 4.8 ± 0.9 | 5.5 ± 1.0 |
Compound | Young’s Modulus (MPa) | Stress at Yield (MPa) | Elongation at Yield (%) | Elongation at Break (%) |
---|---|---|---|---|
DC | 2461 ± 191 | // | // | 1.8 ± 0.5 |
DC-An | 2730 ± 55 | // | // | 2.0 ± 0.3 |
DC-Ox | 2363 ± 70 | 51.5 ± 1.8 | 3.2 ± 0.1 | 152 ± 95 |
DC-J | 2489 ± 186 | 59.4 ± 9.1 | 3.6 ± 0.2 | 35.0 ± 12 |
LC | 2545 ± 231 | // | // | 2.4 ± 0.4 |
LC-An | 2281 ± 23.0 | 57.1 ± 2.3 | 3.8 ± 0.1 | 43 ± 21 |
LC-Ox | 2406 ± 219 | 52.5 ± 8.7 | 3.2 ± 0.3 | 171 ± 12 |
LC-J | 2280 ± 79 | 55.7 ± 2.6 | 3.7 ± 0.1 | 11 ± 6 |
Compound | Flexural Modulus (MPa) | Stress at Yield (MPa) | Stress at Break (%) | Deformation at Break (%) |
---|---|---|---|---|
DC | 1951 ± 135 | // | 54 ± 17 | 3.4 ± 1.5 |
DC-An | 1779 ± 42 | // | 47 ± 6 | 2.9 ± 0.4 |
DC-Ox | 1886 ± 239 | 66 ± 10 | 59 ± 11 | 6.3 ± 2.5 |
DC-J | 2230 ± 181 | // | 54 ± 9 | 4.6 ± 1.7 |
LC | 2289 ± 106 | // | 46 ± 5 | 2.1 ± 0.2 |
LC-An | 2280 ± 102 | // | 49 ± 8 | 2.3 ± 0.6 |
LC-Ox | 2355 ± 411 | 80 ± 7 | 60 ± 23 | 5.9 ± 1.3 |
LC-J | 2323 ± 164 | // | 59 ± 8 | 2.8 ± 0.6 |
Compound | Flow Direction (%) | Transverse Direction (%) |
---|---|---|
DC | 0.97 | 2.72 |
DC-An | 0.98 | 2.73 |
DC-Ox | 0.96 | 2.81 |
DC-J | 0.85 | 2.73 |
LC | 0.91 | 2.60 |
LC-An | 0.91 | 2.84 |
LC-Ox | 0.92 | 2.36 |
LC-J | 0.79 | 2.28 |
Compound | Tm (°C) | Tc (°C) | ΔHm (J/g) | Crystallinity (X) (%) |
---|---|---|---|---|
DC | 252 | 201 | 49.8 | 35.6 |
DC-An | 253 | 202 | 49.0 | 35.0 |
DC-Ox | 250 | 200 | 54.2 | 39.0 |
DC-J | 251 | 201 | 50.1 | 35.7 |
LC | 256 | 206 | 45.1 | 32.2 |
LC-An | 253 | 204 | 49.8 | 35.6 |
LC-Ox | 254 | 204 | 46.7 | 33.4 |
LC-J | 255 | 205 | 48.7 | 34.8 |
Compound | Maximum Number of Linkages per Molecule | ΔMFR (g/10 min) | Ductility Improvement % (Tensile) |
---|---|---|---|
DC-An | 4 | 6.3 | 11 |
DC-Ox | 2 | 2.6 | 8344 |
DC-J | 23 | 18.4 | 1844 |
LC-An | 4 | 14.35 | 1692 |
LC-Ox | 2 | 5.95 | 7025 |
LC-J | 23 | 19.45 | 358 |
Chain Extender | Macromolecular Design | Melt Fluidity (g/10 min) | Ductility (Elong. %) |
---|---|---|---|
Ox | Linear | High (>20) | High (>150) |
An | Slightly branched | Medium (>10) | Medium |
J | Branched | Low (>5) | Medium |
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Bianchi, S.; Pinna, M.; Bartoli, F.; Minei, P.; Filidei, D.; Coltelli, M.-B. Recycling Textiles: From Post-Consumer Polyester Garments to Materials for Injection Molding. Polymers 2025, 17, 748. https://doi.org/10.3390/polym17060748
Bianchi S, Pinna M, Bartoli F, Minei P, Filidei D, Coltelli M-B. Recycling Textiles: From Post-Consumer Polyester Garments to Materials for Injection Molding. Polymers. 2025; 17(6):748. https://doi.org/10.3390/polym17060748
Chicago/Turabian StyleBianchi, Sabrina, Michele Pinna, Flavia Bartoli, Pierpaolo Minei, Daniele Filidei, and Maria-Beatrice Coltelli. 2025. "Recycling Textiles: From Post-Consumer Polyester Garments to Materials for Injection Molding" Polymers 17, no. 6: 748. https://doi.org/10.3390/polym17060748
APA StyleBianchi, S., Pinna, M., Bartoli, F., Minei, P., Filidei, D., & Coltelli, M.-B. (2025). Recycling Textiles: From Post-Consumer Polyester Garments to Materials for Injection Molding. Polymers, 17(6), 748. https://doi.org/10.3390/polym17060748