Development of asphaltene-derived carbon fiber reinforced composites via additive manufacturing

Carbon fiber reinforced composites are sophisticated materials that are blends of carbon fibers (CFs) with a polymer matrix, providing outstanding strength, stiffness, and lightweight properties. Petroleum asphaltenes, the heavy fraction of bitumen, offer high aromaticity and carbon content, making them a cost-effective and promising raw material to produce high-value CFs. This study investigates the utilization and effectiveness of asphaltene-derived carbon fibers (ACFs) in composites produced through additive manufacturing. The composites were 3D printed by incorporating different weight proportions (0 %, 2.5 %, 5 %, and 7.5 %) of chopped ACFs (length 3–4 mm, diameter ∼6–12 μm, tensile strength ∼500–1150 MPa, tensile modulus ∼40–90 GPa) without any post-treatment (without surface functionalization and sizing). Extensive characterizations were carried out on both ACFs and their derived composites to evaluate their mechanical (tensile, flexural, hardness, impact, etc.) properties to identify potential applications. Furthermore, the reinforcement ability of ACFs was assessed in contrast to composites produced from expensive commercial carbon fibers derived from polyacrylonitrile. Incorporating 7.5 wt% ACFs into the acrylonitrile butadiene styrene (ABS) matrix enhanced ABS's flexural and tensile strengths by ∼20 % and ∼5 %, and its corresponding modulus values by ∼30 % and ∼34 %, respectively. In addition, ABS's hardness was improved by 31 % with the inclusion of 7.5 wt% ACFs. This composite performance by incorporating ACFs is encouraging despite the lower surface roughness and surface energy of ACFs (due to the absence of surface functionalization and sizing) as well as their lower tensile strength and modulus properties as compared to commercial surface-functionalized and sized carbon fibers.