Textile carding technology: evaluation and first characterization of different hybrid non-woven materials from recycled fibers

In a circular economy-based approach, fibers reclaimed from EoL composite parts or, more generally, waste fibers produced during textile fabrication could be upcycled into reinforcement for sustainable composite products. With the intent of exploiting at best the reinforcing effects of non-continuous recycled fibers, a possible solution would be the transformation into non-woven fabrics. Some of the most common dry-laid techniques for non-woven fabric preparation are carding and needle-punching. These methods allow the hybridization of reinforcement by simple calibration of the mix of fibers that are fed to the process. Hybrid non-wovens offer many advantages, as they make possible to tune mechanical properties, energy dissipation, thermal conductivity and costs of the final composite. To achieve fully sustainable composite materials, it is desirable to adopt thermoplastic matrices, and, to overcome impregnation issues related to their high melt viscosity, dedicated processing techniques should be used. In our work we investigated different hybrid non-wovens and different preparation methods. Recycled glass/carbon fiber composites were prepared by vacuum infusion with a reactive acrylic resin, suitable for in-situ polymerization (Elium®, Arkema). Recycled basalt/carbon and silk/carbon fiber composite were prepared with the same technique, using epoxy resin as preliminary study. Moreover, we prepared recycled carbon fiber/PA6 composites with hybrid reinforcement/matrix non-wovens. Thermo-compression was adopted as the final step, to promote matrix diffusion and form the final composite. In all cases, not only was the preparation of different hybrid non-wovens successful but the impregnation and the subsequent preparation of the composite gave positive results. A thorough morphological and mechanical characterization was carried out to investigate the different materials obtained. Although improvements in terms of fiber content and porosity should be sought, the results are promising for medium range applications in automotive, construction and transportation sectors.