3D printed polycaprolactone/paper mill sludge prototypes: preparation and characterization

Paper mill sludge is a high-volume waste of the pulp papermaking industry, containing calcium carbonate and a minor amount of cellulose fiber. From a circular economy perspective, the exploitation of this material represents the only possible choice for a more sustainable future. In this reagard, this research investigated the valorization of paper mill sludge, recovered by Lucart company, as filler in the preparation of polycaprolactone composites which were prepared by hot melt extrusion to obtain filaments. Then, a Fused Deposition Modeling 3D printer was used for the fabrication of polycaprolactone-paper mill sludge prototypes. A preliminary thermal and mechanical characterization of the new polycaprolactone-paper mill sludge samples was performed, and the achieved results were compared with those obtained for neat polycaprolactone. The thermogravimetric analysis of the obtained samples allowed us to investigate their thermal degradation profile, highlighting as the thermal stability of the composites slightly increases at the increase of filler loading. The mechanical properties show a more pronounced brittle behavior of the final material prepared with the high paper mill sludge loadings.