Influence of Cork Waste Processing in the Fabrication of Polymer Composites by Additive Manufacturing

This work evaluates the influence of processing on the production of various cork composites. Cork agro-waste with different particle sizes, namely fine cork (FC, D_p < 250 µm) and coarse cork (CC, 1 mm < D_p < 2 mm), was valorized. It was possible to process composites containing up to 20 wt.% FC and 15 wt.% CC using a twin-screw extruder. These composites were subsequently manufactured via large-format additive manufacturing (LFAM) using fused granular fabrication (FGF). The effects of cork concentration and processing duration in the extruder on particle integration, as well as on the mechanical, physical, and thermal properties of the composites, were studied. As expected, a linear decrease in mechanical properties was observed with increasing cork content. For the same cork content and longer processing durations, properties were similar for FC and CC composites. Shorter processing durations in the extruder minimized degradation of FC. However, partial degradation occurred during FGF printing, leading to the formation of composite foams with increased porosity, lower density, and enhanced thermal insulation.