Mechanical Properties of Recycled Carbon Fiber-Reinforced Resin Composites 3D Printed via Digital Light Processing

Additive manufacturing, particularly with UV-curable resin-based 3D printing, has revolutionized production processes, allowing precise fabrication of intricate geometries. However, challenges persist in composite printing, particularly in meeting the demand for second-life applications due to the considerable volume of carbon fiber waste. This study addresses this issue by researching the compatibility of mechanically produced recyclable carbon fibers with UV-curable resin. The short carbon fibers were combined with the resin at varying weight percentages (1.5, 3, 6, 9, 12, and 15 wt.%) to determine the optimal ratio for achieving maximum Young's modulus and tensile strength in resulting composites. Utilizing digital light processing (DLP) 3D printing technology, the study systematically evaluated composite roughness, surface hardness, and voids volume. Each 3 wt.% increase in recycled carbon fiber concentration within the UV-curable resin resulted in a 0.01 g/cm3 density decrease, accompanied by a 0.02 mu m increase in surface roughness, with no impact on hardness. Notably, the 3 wt.% concentration proved optimal, exhibiting a 27% increase in Young's modulus and a 44% increase in tensile strength compared to the pure resin.