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

Abstract

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 V f 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 V f = 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.

The degradation during recycling of polyamide 6 produced by anionic ring-opening polymerization of ε-caprolactam

“…Previously, the problem with continuous fiber–reinforced thermoplastic composite manufacturing technologies was that the high viscosity of the thermoplastic matrix material did not allow the sufficient impregnation of the reinforcing fibers, limiting the spread of the technology. The solution could be Thermoplastic Resin Transfer Molding (T-RTM), which is ideally suited for anionic ring-opening polymerization 7 – 9 . T-RTM has advantages over thermoset composite manufacturing technologies, such as recyclability, lower environmental impact, and the ability to create different layering patterns of reinforcing fabrics within a product for different loads.…”