Marine plastic waste from fisheries has emerged as a significant environmental issue, posing a significant threat to marine biodiversity and ecosystem health. The material recycling of fishing gear is an effective way to reduce waste and promote a circular economy. This study examines the characteristics of virgin and used fishing nets and ropes to understand their recyclability before they are discarded. The used nets and ropes in this study were in service for up to two years. The material characteristics were identified based on Fourier-transform infrared (FTIR) spectroscopy while thermal properties were obtained using differential scanning calorimetry (DSC). Based on FTIR results, the main polymer of the fishing nets was found to be PE, while the fishing ropes were found to be a blend of PE/PP and a combination of PE/PP and PET. The aging and oxidation process produces new bands in the infrared (IR) spectra of PE and PP fishing nets and ropes. The significant differences between used and virgin materials were also obtained in terms of crystallization enthalpies. This suggests that the fishing nets and ropes were affected by environmental factors.

Plastic waste in coastal waters has become a major environmental concern and a visible sign of ocean pollution. A significant share of the floating waste material originates from used and lost fishing gear. By establishing suitable recycling processing chains, used fishing gear can become a valuable resource for the manufacturing of products, fostering its extraction from the water and boosting local economies. Post-use fishing gear, however, is a very challenging input material for processing into recylcates. Understanding its degradation mechanisms is crucial for designing a recycling process that will yield high value materials. There are particular obstacles connected with each recycling step, starting with the collection of very heterogeneously aged and deteriorated fishing gear. Consecutively, shredding of the waste material requires the development of specific technological solutions. Marine dirt adds additional obstacles. Further processing steps that need to be adapted include extrusion, pelletizing injection molding and marketing of the products from recycled material in competition with ones using raw materials. This study presents a waste-to-value process chain design that addresses the specific challenges of recycling fishing gear collected from coastal waters. Data has been collected to identify and quantify sources of plastic waste from fishing activities, and solutions have been developed in local higher education through a joint German-Vietnamese effort.

Reliable polymer identification is a prerequisite for high-quality recycling of post-consumer fishing nets and ropes. Differential Scanning Calorimetry (DSC) provides precise thermal characterization but requires stationary laboratory infrastructure and is not applicable at coastal collection points or small-scale recycling operations. This study describes and validates Melting Box 1.0 (MB 1.0), a low-cost, field-deployable device for qualitative screening of softening and melting ranges in small polymer samples. MB 1.0 repurposes a commercial vaporizer’s existing temperature-controlled heating and display functionality into a purpose-built screening tool, rather than introducing a new analytical measurement principle. Representative materials from Vietnamese fishing net recycling projects—polyethylene (PE), polypropylene (PP), polyamide (PA), and PE/PP blends—were assessed with a standardized three-tier visual scale (0 = no change; * = softening; x = melting) across five replicate measurements per sample. Agreement with the Kofler hot bench is good (mean bias for T_melt,start: +2.9 °C; SD = 9.1 °C; n = 7), and a systematic offset of +20.6 °C (range +14.1 to +27.6 °C) was observed for PE relative to DSC first-heating peak-end temperatures. The correct material ranking (PE < PP < PA) is preserved, and all four polymer groups are reliably distinguished. At an estimated cost of 150–200 EUR—one to three orders of magnitude below the Kofler hot bench, portable NIR, or DSC—MB 1.0 is intended as a field-deployable screening complement to, not a replacement for, laboratory-grade analytics in resource-constrained recycling contexts.