Investigation and comparison of recycled marine PA6 with PA6/66 copolymer and chopped fibre reinforced PA12: evaluating sustainable polyamide additive manufacturing

Purpose This study aims to evaluate the potential of using material extrusion (MEX) for the re-manufacturing of waste marine nylon through an investigation of the mechanical performance, crystalline structure, molecular composition and morphology. The authors compare the marine nylon performance to standard nylon copolymers and nylon reinforced with chopped carbon fibre to demonstrate the potential of this recycled material. Design/methodology/approach This study assesses the mechanical properties of the various nylon materials through a combination of tensile, compression and hardness testing. Crystalline structure is determined using multi-phase differential scanning calorimetry, while the molecular properties are evaluated using Fourier transform infrared spectroscopy. Findings Marine nylon is found to have high strength in comparison to nylon containing chopped fibre reinforcement and a standard nylon copolymer, highlighting the potential of the material for manufacturing purposes where high tensile and compressive yield strengths are required. The authors also document some of the limitations of this material, particularly with respect to the impact of water absorption. This analysis also highlights the disparity in reported mechanical properties of additively manufactured nylons, which warrant new forms of standardisation, which capture inherent differences of like nylon polymers. Originality/value To the best of the authors’ knowledge, this study is the first examination of recycled marine nylon using MEX technology and which provides a comparison between standard and reinforced nylon material variants. The authors also discover several unique mechanical properties, which exhibit both normal and shear-based compressive failure, and which is due to the resulting crystalline formation of the nylon during MEX. This work validates the potential of recycled marine nylon using MEX for new end-of-life re-manufacturing.