Mechano-morphological studies of polyamide 6 based single polymer laminate composites prepared by different reactive processing techniques

Single polymer laminate composites based on polyamide 6 (PA6) were prepared by two methods: (i) reactive injection molding and (ii) powder coating/compression molding, both carried out in the presence of PA6 woven textile plies. The effect of the textile volume fraction Vf on the tensile properties of all composites was investigated. The laminates obtained by powder coating/compression molding displayed best mechanical performance, whereby in the composites with Vf = 15%, the improvement of the elastic modulus reached 98% in respect to commercial hydrolytic PA6 reference, or 50–86% as compared to neat anionic PA6 samples. Polarizing light microscopy with image processing was used for morphological characterization. A transcrystalline layer at the fiber-matrix interface was detected in all laminates with thicknesses between 0.5 and 3.0 μm, depending on the preparation technique applied. The thermal stability was studied in the temperature range of 30°C-550 °C. The laminates obtained by reactive injection molding displayed the lowest initial decomposition temperature due to the presence of oligomers. Selected laminate composites were reprocessed by grinding and injection molding. The recycled composites obtained by powder coating displayed a 38% increase of the elastic modulus in respect to commercial hydrolytic PA6 thus confirming the sustainability and recyclability of PA6-based single polymer composites.This work was partially financed by FEDER funds through the COMPETE program and by national funds through FCT – Foundation for Science and Technology within the project .POCI-01-0145-FEDER 007136 SDT thanks FCT for his PhD Grant SFRH/BD/94759/2013. ZZD and NVD thank the National Funds through FCT-Portuguese Foundation for Science and Technology, project reference UID/CTM/50025/2019. All authors gratefully acknowledge the support of the project TSSiPRO NORTE-01-0145-FEDER-000015 funded by the regional operational program NORTE 2020, under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund