Solvolysis of Nylon: A Pathway to Sustainable Recycling and Circular Economy

Nuno Gama (), Jéssica Araújo, Bruno Godinho, Artur Ferreira and Ana Barros-Timmons
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Nuno Gama: CICECO—Aveiro Institute of Materials and Department of Chemistry, University of Aveiro, Campus Santiago, 3810-193 Aveiro, Portugal
Jéssica Araújo: CICECO—Aveiro Institute of Materials and Department of Chemistry, University of Aveiro, Campus Santiago, 3810-193 Aveiro, Portugal
Bruno Godinho: CICECO—Aveiro Institute of Materials and Department of Chemistry, University of Aveiro, Campus Santiago, 3810-193 Aveiro, Portugal
Artur Ferreira: CICECO—Aveiro Institute of Materials and Águeda School of Technology and Management, Rua Comandante Pinho e Freitas, No. 28, 3750-127 Águeda, Portugal
Ana Barros-Timmons: CICECO—Aveiro Institute of Materials and Department of Chemistry, University of Aveiro, Campus Santiago, 3810-193 Aveiro, Portugal

Sustainability, 2024, vol. 16, issue 22, 1-13

Abstract: Polyamides (PAs) are extensively utilized across various applications, yet the accumulation of PA residues presents significant ecological and environmental challenges. Given that a substantial portion of fishing nets are composed of nylon, a type of PA, this material’s disposal raises environmental concerns impacting marine life and the global ecosystem. Therefore, to enhance sustainability, they could be collected and recycled. This study introduces a method for the chemical recycling of PA waste using hydrochloric acid (HCl). Through solvolysis, a PA was depolymerized, and the effect of various reaction conditions on the depolymerization yield was analyzed, being the best conditions established in this work (100 °C, 4 h, and an HCl/PA ratio of 11:1, wt.wt −1 ). Next, a novel separation methodology was employed to isolate recycled products from salts formed during neutralization. Subsequently, these recycled products were incorporated as a partial substitute (up to 10% wt.wt −1 ) for a conventional PA in a new material production. The results indicate that the presence of recycled products enhances material stiffness due to crystallinity differences compared to the virgin matrix. In turn, the introduction of lower-molecular-weight species increases the materials’ glass transition temperature (Tg) and their melt flow index (MFI). This research underscores a sustainable pathway for PA recycling aligned with circular economy principles, contributing positively to environmental conservation efforts.

Keywords: polyamide; nylon; recycling; circular economy; acidolysis (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2024
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