Correlation of Microstructural Features within Short Carbon Fiber/ABS Manufactured via Large-Area Additive- Manufacturing Beads

• Published in: Journal of composites science Vol. 8; no. 7; p. 246
• Main Authors: Sayah, Neshat, Smith, Douglas E.
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.07.2024
• Subjects: ABS resins; Acrylonitrile butadiene styrene; Additive manufacturing; Aluminum; Beads; Carbon fiber reinforced plastics; Carbon fiber reinforcement; Computed tomography; Correlation; Extrusion; Fiber composites; Fiber orientation; Fiber reinforced polymers; Fiber volume fraction; Heat conductivity; Manufacturing; Mechanical properties; Microstructure; Polymer matrix composites; Polymers; Printing; Raw materials; Tensors; Voids; United States > US
• ISSN: 2504-477X; 2504-477X
• DOI: 10.3390/jcs8070246

Short carbon fiber-reinforced polymer composites are widely used in polymer extrusion additive manufacturing (AM), including large-area additive manufacturing (LAAM), due to their enhanced mechanical properties as compared to neat polymers. However, the mechanical properties of these composites depend on microstructural characteristics, including fibers and micro-voids, which are determined during processing. In this work, the correlation between fibers and micro-voids within the microstructure of LAAM polymer composites throughout various processing stages of short carbon fiber-reinforced acrylonitrile butadiene styrene (SCF/ABS) is investigated. The processing stages considered here include the incoming pellets, a single freely extruded strand, a single regularly deposited bead, and a single regularly deposited bead pressed by a mechanical roller. A high-resolution X-ray micro-computed tomography (µCT) system is employed to characterize the microstructural features in terms of the fibers (volume fraction, fiber orientation tensor) and micro-voids (volume fraction, sphericity) in the SCF/ABS samples. The results indicate that micro-voids exist within the microstructure of the SCF/ABS composite in all four stages considered here and that the micro-void volume fraction and micro-void sphericity vary among the test samples. Moreover, the results show a considerable variation in fiber orientation and fiber volume fraction within the microstructure throughout all the stages considered; however, all the samples show the highest alignment in the extrusion/print direction. Furthermore, a correlation is identified between the fiber orientation and the micro-void volume fraction within samples from all four stages considered here. This finding suggests that fibers tend to align more in the extrusion/print direction in regions with less micro-void content.