Purpose. The accumulation of plastics, including 640,000 tons annually from discarded fishing gear (20% of marine plastics), poses a severe threat to marine ecosystems. Circular economy strategies aim to address this issue by promoting the reuse and recycling of marine plastic waste. Method. In this context, this study focuses on developing sustainable composites using recycled polyamide 6 (rPA6) from fishing nets, reinforced with biochar derived from vegetable biomass and recycled carbon fibers (rCF). Results. In the first polymer composite, lignocellulosic biochar (5-15 wt.%) enhanced rPA6’s mechanical properties and moisture resistance. The elastic modulus increased from 2.6 to 4.5 GPa, while water uptake decreased from 3.6 to 1.8 %. Additionally, rice husk-derived biochar, rich in silica, acted as a flame retardant by improving combustion resistance without significantly altering water uptake or mechanical behavior. The second polymer composite incorporated rCF produced through an innovative two step thermo-oxidative process. This method enhanced rCF’s compatibility with rPA6 by increasing surface activation (O/C weight ratio of 0.054 vs. 0.021 for virgin fibers) while preserving fiber dimensions (7-8 µm), mechanical strength (282 ± 35 vs. 293 ± 20 GPa), and surface smoothness. At 15 wt.% loading, rCF/rPA6 composites achieved a tensile modulus of 13.1 GPa and impact toughness of 28.4 kJ/m², compared to rPA6 alone (3.2 GPa and 11.8 kJ/m²). A Life Cycle Assessment (LCA) compared scenarios involving virgin materials and recycled components. The fully recycled scenario achieved a reduction of approximately 5.74 × 10³ kg of CO₂ equivalents, demonstrating significant emission savings despite slight increases associated with wastewater treatment. Conclusions. This study demonstrates the potential of repurposing marine polyamide 6 waste into high-performance polymer composites for lightweight applications, including automotive and construction. By incorporating sustainable biochar and recycled fibers, these materials deliver superior mechanical properties and a reduced carbon footprint, supporting waste recovery initiatives and promoting sustainable development goals.
Polyamide 6 recycled fishing nets modified with biochar fillers and reclaimed carbon fibers: an effort toward sustainability and circularity
Damiano Rossi
;Miriam Cappello;Sara Filippi;Patrizia Cinelli;Francesco Pasciucco;Isabella Pecorini;Maurizia Seggiani
2025-01-01
Abstract
Purpose. The accumulation of plastics, including 640,000 tons annually from discarded fishing gear (20% of marine plastics), poses a severe threat to marine ecosystems. Circular economy strategies aim to address this issue by promoting the reuse and recycling of marine plastic waste. Method. In this context, this study focuses on developing sustainable composites using recycled polyamide 6 (rPA6) from fishing nets, reinforced with biochar derived from vegetable biomass and recycled carbon fibers (rCF). Results. In the first polymer composite, lignocellulosic biochar (5-15 wt.%) enhanced rPA6’s mechanical properties and moisture resistance. The elastic modulus increased from 2.6 to 4.5 GPa, while water uptake decreased from 3.6 to 1.8 %. Additionally, rice husk-derived biochar, rich in silica, acted as a flame retardant by improving combustion resistance without significantly altering water uptake or mechanical behavior. The second polymer composite incorporated rCF produced through an innovative two step thermo-oxidative process. This method enhanced rCF’s compatibility with rPA6 by increasing surface activation (O/C weight ratio of 0.054 vs. 0.021 for virgin fibers) while preserving fiber dimensions (7-8 µm), mechanical strength (282 ± 35 vs. 293 ± 20 GPa), and surface smoothness. At 15 wt.% loading, rCF/rPA6 composites achieved a tensile modulus of 13.1 GPa and impact toughness of 28.4 kJ/m², compared to rPA6 alone (3.2 GPa and 11.8 kJ/m²). A Life Cycle Assessment (LCA) compared scenarios involving virgin materials and recycled components. The fully recycled scenario achieved a reduction of approximately 5.74 × 10³ kg of CO₂ equivalents, demonstrating significant emission savings despite slight increases associated with wastewater treatment. Conclusions. This study demonstrates the potential of repurposing marine polyamide 6 waste into high-performance polymer composites for lightweight applications, including automotive and construction. By incorporating sustainable biochar and recycled fibers, these materials deliver superior mechanical properties and a reduced carbon footprint, supporting waste recovery initiatives and promoting sustainable development goals.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
